Window Procedure: 9. Sash Glazing & Painting (Video).
Post new topic   Reply to topic
Historic HomeWorks Forum Forum Index -> Windows & Doors Goto page 1, 2, 3, 4, 5, 6, 7, 8, 9  Next 
View previous topic :: View next topic  
Author Message
Site Admin

Joined: 20 Aug 2004
Posts: 3009
Location: Portland, Maine, USA

PostPosted: Sun Jun 10, 2007 7:55 pm    Post subject: Window Procedure: 9. Sash Glazing & Painting (Video). Reply with quote

(update: 5/30/14 new training video, 6/21/12 bedding details)

Basic overall procedure to refurbish windows:
(excerpt from Save America's Windows)

1. Remove sashes from frame, install temporary weather panel
2. Move sashes to onsite or remote workshop
3. Remove heavy paint buildup from frame and sill
4. Repair sills, paint sills and frames
5. De-glaze (remove glass) sashes, remove paint, cleanup
6. Mill out stock for replacement sash parts
7. Cut & fit stock for each sash repair
8. Repair wood of sashes
9. Re-glaze and paint sashes
10. Move sashes back to site and distribute to window locations
11. Re-install sashes in frame and tune up for proper operation

Step 9. is detailed here:

Sash Glazing and Painting Procedure

"To glaze well, neatly and expeditiously, simple as the operation may appear, is an art not to be acquired in a day." --Daniel Cooper, master glazier, 1835

Glazing and painting a sash involves distinctively different materials:

Glass: brittle, stiff, easily broken by a sharp blow, readily cut to any size
Wood: stiff, strong, slightly flexible, swells a bit when wet, shrinks back when dry
Metal: tiny points to hold the glass in place
Putty: soft and pliable now, hardening to a resilient solid, ages to hard and eventually crumbles out
Paint: a sticky liquid now, drying into a flexible weather-resistant film

that you weave together creating a system that performs for decades to resist the weather, yet give you a view of the great outdoors and the universe beyond, and then fail in a graceful way, so the sash can be glazed and painted again.

The following procedure assumes the double-hung sash are new and unprimed bare wood, or have had all paint and putty removed down to bare wood, and that all woodwork repairs have been done.

Do not apply any treatments, primer or paint to the side edges of double hung sash. Leave the edges bare wood, which leaves a surface where the wood of the sash can dry out, preventing peeling paint and keeping the wood free of fungal decay.

9a. Pre-Treat.

A pre-treatment may not be necessary if all the wood is perfectly sound (as with all new wood) and a very effective primer is used, but I find I can lengthen the service life of the paint coatings on old wood with this "fine tuning" of the coating system. Scientific studies at the Forest Products Laboratory have clearly demonstrated that a paintable water repellent preservative effectively adds to the protection of the wood and dramatically limits fungal decay extending the window's life.

In many cases the exposed surfaces of the sash are weathered and need a pre-treatment, while the glazing rabbet is perfectly sound wood and needs no treatment because it has been protected from the weather by the putty and glass. In fact, a pre-treatment in the rabbet may prevent good adhesion of the putty because the oil of the putty cannot seep slightly into the surface of the rabbet. This must be balanced with the fact that too much oil can seep out of the putty, leaving the putty weak right along the surface of the rabbet, leading to putty adhesion failure. The proper balance is found in the worker who can judge the character of the wood and the putty to create a successful and long-lasting seal between the wood and the glass.

One of the traditional practices is to always pre-treat the glazing rabbet with linseed oil, or a linseed oil and turpentine mixture. This still works, but some scientific studies have demonstrated that linseed oil acts like food for the mold and bugs that damage paint and wood. A recent practice to avoid this is to use other materials to seal the glazing rabbet, such as alkyd-resin oils and primers, that are less like food to the mold and bugs.

If needed, apply a penetrating pre-treatment to the bare wood. Apply the pre-treatment to both faces of the sash, all muntin bars and muntins, possibly including the glazing rabbets. The bottom edge of the lower sashes' bottom rail may need treatment if it shows signs of deterioration caused by water; if the bottom edge is in good condition it should not be treated since it has done well for so many years without treatment. Do not apply pre-treatment to the side edges of the sashes, and the top edge of the upper sash.

There are two types pre-treatment, paintable water-repellent preservative and consolidating oil-resin.

Paintable water-repellent is suitable for sound wood surfaces. (if waxy paraffin type (Forest Products Lab's WRP Recipe, Thompson's WaterSeal, or similar) apply to all surfaces of the sash, if sticky oil or resin type do not apply to sash edges (the surfaces that run in the jamb's sash tracks) and face margins (the narrow strip where the face of the sash rubs on the parting bead or the stops)

Consolidating oil-resin treatment is suitable for gray weathered wood surfaces or surfaces that are somewhat "soft" or more porous than perfectly sound wood. The traditional recipe for this treatment is linseed oil and turpentine. I no longer use linseed oil because it is susceptible to mold and fungus attack. I now use a 50%-50% mix of mineral spirits and oil-based alkyd-resin varnish or a proprietary product (Flood's Penetrol, or similar)

When using an oil pre-treatment on the bare wood I try to do the next step (whether it is putty or primer), before the oil is completely cured and dry. This allows the oil in the putty or primer to "knit" together chemically with the oil that is in the wood providing better adhesion. If I wait until the oil treatment is completely dry the next putty or primer might not "knit" in and adhere quite as well. If I'm using a 50-50% mix of Penetrol and mineral spirits this might be in just 4 to 6 hours since Penetrol has a lot of driers in it. For a more traditional boiled linseed oil and turps mixture it might be 12 to 24 or more hours. The drying times might be different than this because it depends a lot on air temperature, air movement and humidity.

Just to confuse us all, there are some combination products that may be suitable. (California's Storm Stain Penetrating Wood Stabilizer, or similar) Water-based products of both types MAY be suitable, but all my experience and this recommendation is for oil-based products.

Penetrol is an oil-based product made of mineral spirits, linseed oil, alkyd resin and dryers that penetrates deeply into the wood surface. The mineral spirits evaporate leaving behind the oil and resin that cures and consolidates loose fibers at, and just beneath, the wood surface. Apply putty or paint primer when the pre-treatment is 80% cured. "80% cure" can be determined when the surface is still slightly tacky, and not yet "dry." The amount of cure time is dependent on weather or shop conditions. Penetrol is like a light varnish or like an alkyd-resin oil-based paint without the pigment.

Storm Stain is a waterborne product that contains zinc napthanate and a very tiny amount of resins. Zinc napthanate is a preservative that limits mold, mildew and fungus. The resins help hold the zinc napthanate in the wood, but there is not enough resin to consolidate loose fibers at the surface of the wood. Storm Stain does not penetrate as deeply as oil-based pre-treatments because it is waterborne. After 24-48 hours the water has evaporated, the wood surface is dry, slightly tacky to the touch and ready for paint primer.

9b. Prime. Do not prime the side edges of the sash that run in the tracks. Prime all surfaces of the entire sash with oil-based alkyd resin primer, except side edges and face margins. Prime the glazing rabbets if the pre-treatment was a water-repellent preservative. Do not prime the glazing rabbets if the pre-treatment was an oil-resin. This rule-of-thumb can be modified within following guidelines:

-- No priming or painting of the top edge of the upper sash because it usually doesn't need protection from moisture when the sash are single-hung or if double hung and the top sash is not operated
-- The top edge of the upper sash does need paint protection from the weather if it is a casement window
-- The bottom edge of the lower sash may need painting, especially if it had extensive deterioration due to moisture on the sill.

Allow primer to dry thoroughly.

9?. Clean glass, both sides, wet-wash method. Here is the complete method:

9c. Glaze.

Glazing Putty Types

Traditional Putty, Linseed Oil Type, knife grade, hardening (typically contains boiled or raw linseed oil, whiting)
specific products:
- Allback Linseed Oil Putty (can paint immediately with Allback paint)
- Crawford’s Natural Blend Painters Putty
- Old-Time (no longer available)

Glazing Compound, Modified Oil Type, semi-hardening (typically contains a mixture of oil types, linseed oil, soybean oil, mineral oil, plasticisers, drying agents, whiting, limestone, talc)
specific products:
- Sarco MultiGlaze Type M (skins over in a few or several days, for indoor use only, the good stuff)
- Sarco Dual Glaze (longer skin over, longer lasting in service, for outdoor use only, the good stuff)
- Glazol (can be good if you add a little boiled linseed oil)
- Perm-E-Lastic
- DAP 33 (for goodness sake, don't use this stuff)
- Perma-Glaze (no longer available)

Acrylic Elastomeric Type, flexible, gun grade (typically contains acrylic resin, water)
specific products:
- Glaze-Ease 601 (dries quickly for painting within 24 hours)

Acrylic Type, hardening
specific products
- Aqua-Glaze (dries quickly for painting within a few hours)
- Elmer’s Glaze-tuff

Ingredients in the various putty products:

Discussion on coloring putty:

Here's a formula from Justin Smith to calculate the amount of putty needed:

For a brief explanation of the types of putty, and putty handling see this video replay of the live glazing demonstration:

Then watch this video for glazing methods and techniques:

Video: complete glazing procedure, 36 min.

Spacer Blocks
Panes wider than 24” may require spacer blocks. Spacer blocks are needed around larger panes because they are heavier and may shift position, disturbing the putty before it has firmed up. These little blocks are about the thickness of the pane and an inch or so long. They might be made out of wood (like a match stick) or glass (made from glass cutting scraps) or made of a hard rubber especially for this purpose. The blocks are placed between the edges of the pane and the neck of the glazing rabbet and held in place by the glazing point that also holds the pane. The panes have to be sized to allow enough space for the blocks.

Apply glazing putty to glazing rabbets as bedding. Bedding seals the glass to the wood keeping water from interior condensation out of the wood. If working in a cold shop warm the putty slightly with a hot-air gun or infra-red lamp. Set the pane of glass in place and be sure the bottom edge of glass is actually resting on the neck of the lower glazing rabbet (for panes up to 18" wide). Jiggle the glass slightly so that it beds down into the putty, leaving about 1/16" of putty between the glass and the shoulder of the glazing rabbet, with some putty squeezing out all along the edges of the glass.

Install glazing points.
See the Glazing Points discussion here:
Swedish glazing pin-rods and triangular glazing hammer discussion:

Apply and tool glazing putty in the form of a bevel to make water-tight seal between the glass and the wood using the 3-step method: Place, Pack & Tool. Immediately "polish" outside of glass with whiting in a dry soft paint brush to clean oil from the putty off of glass and to "dust up" the surface of the putty. Flip the sash over and remove excess putty from interior joints and tool down to form water-tight seal at joint between the glass and the wood. "Polish" inside of glass with whiting. Set sash aside in correct vertical position to avoid settling of glass and distortion of beveled putty. Allow putty to cure and skin over for several days or a few weeks if possible.

Place, Pack & Tool. To get the line of putty to stick to the wood and glass use the 3-step method: Place, Pack & Tool. Place and pack each line of putty around the entire sash, it does not have to look good. To place the putty you can make little snakes if it is fun, but this wastes time; simply use your putty knife to quickly distribute the putty. Pack the putty into place by putting the end of the putty knife on the glass and wiggling the knife slightly as you force the putty in. Do this along all the lines of putty all around the sash. This gives the putty 5 or 10 minutes to 'marry' the glass before you start tooling. A little oil seeps out from between the particles of whiting and 'attaches' to the glass. This is actually a form of weak adhesion and it takes several minutes to happen. Then starting at the same corner of the sash, do your final tooling of the lines of putty.

Putty Knife. A 1 1/2" wide putty knife is good for most ordinary glazing. A slightly flexible knife can help the beginner keep from breaking glass or mashing over the arris of wood at the top of the glazing rabbet. A stiff putty knife is usually preferred by the professional because every time the knife flexes it is wasted effort and time. If you have a lot of sash to glaze or intend to be a professional start out with a stiff putty knife. Your putty knife needs to be clean and very smooth. The flat surfaces near the end of the blade should be so shiny you can see the reflection of a face well enough to recognize who it is. Clean and polish the surfaces with a rag after every use, stroking in the same direction that the putty flows when tooling. If your putty knife is not reflective you can polish it or buy a new one that is. Clean off and polish the surfaces with very fine steel wool, stroking in the same direction that the putty flows when tooling. To get reflective surface on an old knife we polish it on a hard cotton buffing wheel mounted on an electric motor arbor, with grey steel-polishing compound. Some new putty knifes have a clear coating to prevent rust, which must be removed or it will drag up the putty during tooling. Try a chemical paint remover. Do not simply scrape it off, you will scratch the metal and every one of those scratches tends to drag out the putty.

Polish the Glass.

Video: Polishing the glass.

Safety: Wear a respirator while polishing with whiting to keep the fine dust out of your nose, mouth and lungs.

"Polishing" the glass and dusting the putty with whiting in a dry brush right after glazing is a far more effective way to clean the glass, helps the putty to begin skinning over, and takes much less time than "wet washing" the sash after the paint has dried.

Get some whiting and take a few minutes to learn this simple method, you will be saving time immediately. Dip a dry brush in the dry whiting powder, then gently whisk the surface of the glass with the ends of the bristles. The whiting will stick to the surface of the glass where there is oil, showing where more whisking is needed. The surface of the putty will not be significantly disturbed if the brush has soft flexible bristles and the polishing is done with care. When the glass is clean, use the same brush to whisk away whiting that has built up in the corners of the putty.

Since the whiting-oil residue contains linseed oil, spontaneous combustion is a fire risk. Be sure to clean up thin dustings and little piles of the residue from around the glazing station immediately. Put the residue in a metal can filled with water. Do not use a vacuum cleaner for the clean up, since an accumulation of the residue might spontaneous combustion inside the vacuum cleaner and fire may spread outside the vacuum.

Types of Whiting
The natural product is ground chalk (calcium carbonate), which can have a range of particle sizes with some courser bits (not usually a problem with ordinary window work). The chemically formed product is precipitated calcium carbonate. The precipitated is a finer and more consistent material. Use only whiting made of calcium carbonate. DO NOT use other materials like pumice, diatomaceous earth, chalk line chalk made in China which may contain silica, plaster of Paris, baby powder, Durabond, etc., which may have significant health risks and are not proven by the traditional trades practice of using whiting.

Whiting Promotes Skin Over
The slight amount of whiting left on the surface of the putty is absorbed by oil from the putty. The whiting on the surface of the putty "kicks off" the skinning of the putty because it brings a small amount of air and oxygen into the outer layer of the putty. If you want a little faster skin over, come back with another dusting of whiting in 12 or 24 hours. But don't push fast drying too much--the faster the drying of the linseed oil, the shorter the service life of the glazing.

Whiting Suppliers:

Local paint dealers used to carry whiting, but few do today. Stained Glass shops use whiting and are often willing to sell out of their supply.

Whittemore-Durgin Glass Co. (stained glass supplier)

Talas Chemical Co., for the chemically precipitated type

Kelp4less at eBay, for the ground limestone type

Backing the glass.
Turn the sash over to see the bedding putty that has squeezed out. With the putty knife, slice out this extra putty, while tooling and packing it down into the joint between the wood and the glass. Remove all the extra putty from the wood and make sure that any gaps are filled with putty. Polish off the the glass with whiting.

9d. Paint.

Video: priming the lines of putty, top coating putty and face of sash, 10 min.

Apply primer to putty bevels and interior seals. Lap primer 1/16" onto the glass, painting "to the line," allow to dry. Apply two top coats of paint to entire sash except side edges and face margins and top and bottom edges if they are not being painted. (Use best quality exterior house paint. Waterborne 100% acrylic paint is good, as is oil-based alkyd resin paint.) Lap paint 1/8" onto to glass. If you can (with practice) lap the paint onto the glass just a bare 1/32" to 1/16", so much the better. Allow paint to dry and cure thoroughly.

The over-paint-and-scrape-back method is problematic. Slopping paint onto a wide margin of the glass and then coming back to scrape it off takes more time time than painting to a line. Slow down and learn to paint to a line, you will be saving time after three to five sashes. (Yes, you can learn to do it, I have taught 13 year old kids, and 72 year old grandmothers to do it, by showing them just once.)

Wet washing right after glazing and painting with solutions containing detergents or vinegar can cause paint failure along the edge of the glass within a year and may shorten the life of the paint and putty. Wait at least a full year for paint and putty to cure completely before washing glass.

Clear finish on interior, paint on exterior of sash:

Finish and Putty Schedule, step-by-step:

strip to bare wood
woodwork repairs if needed
prepare surface of wood (cleaning, sanding, etc.)
stain interior if needed
prime interior with thinned down varnish
coat interior with full coat varnish
seal or oil exterior if needed (including glazing dados)
prime exterior with paint primer
set and glaze glass
coat interior with one or two coats of varnish
prime putty if needed
paint exterior with two coats

Sometimes the putty needs to be colored so it does not show white from the interior view, here are two discussions on this:

Historically, some sash were faux painted with glazes and graining to match varnished interior woodwork to get the better durability. On the exterior side of sash pigmented paint is usual because it provides better durability than clear finishes. If clear finishes must be used on the exterior of sash or the exterior window parts plan on more frequent routine finish and putty maintenance, perhaps at least every other year.

Oil-based spar varnish (long-oil type, made for the marine trade, with UV inhibitors, such as Man-O-War Spar Varnish) will be as good as any clear finish on the interior. Over all expect 5 to 8 year life, the top edges of the meeting rails and top of the lower rail may need spot maintenance every 2 to 4 years. The ultra-violet (UV) rays of the sun break down the UV inhibitors in the film of varnish after a few years and then breakdown the surface of the wood under the film causing peeling.

The old timers had this one figured out: paint holds up longer than any varnish. I see many old sash that were faux-grained on the interior to match the clear varnish or shellac finish of the interior woodwork. Often it's primer, one full coat of a solid color, one or two coats to get the faux-graining then a coat of translucent glaze that might be grained.

I use oil-based alkyd-resin varnish or oil-base long-oil "spar varnish" for sash interiors. I would not use poly-urethane because it does not take spot maintenance well. I have not worked with the acrylic water-based varnishes, but I suspect they would not last as long as oil-based varnishes. I have been testing shellac, which seems to require renewal every 2 to 4 years where direct sunlight hits it.

For clear finishes on the interior face of sash prep the surface by stripping and cleaning down to bare wood. Apply penetrating pigmented stains if needed to get the color required. Apply a thinned down coat of varnish to act as a penetrating "primer," apply one or two topcoats lapping down into the glazing dado. Color the putty with dry pigments to match the interior color of the stain. Bed the glass in colored putty. Apply colored putty in the usual way and tool to finish. Add one more top coat of finish on the interior face of the sash, lapping across the narrow line of bedding putty and onto the glass slightly.

Painting soft putty:
Use a medium-soft or soft brush and a light touch. It is possible to paint freshly applied putty, such and Allback's, and paint right away without damaging the flat surface of the putty. Some American paints do not flow out of the brush easily, which can cause problems with soft putty. If you are using Allback paint it is thin enough to flow out of the brush easily. American paints often require a "flow" additive, such as Flood's Penetrol for oil-base paints or FlowTrol for water-base paints. Just start doing it and adapt your materials and technique to give the result you want.

Brushes for Sash Painting:
My standard most-used brush is a "Purdy"-brand sash brush that is 3" wide and 5/8" thick on smaller lights. I use a 4" or even 5" house painting brush that is 3/4" or 1" thick for single-light sash with long lines of putty. The bigger brushes hold more paint so less time is spent dipping. The "sash brush" (about 1 1/2" x 3/4") provided in the Allback line is too stiff for me. Some sash painters use a 1" round brush with a conical shape at the bristle end for sash work, rotating the brush during the stroke, but this method takes too long for me because the brush does not hold enough paint, and the extra dipping slows down the work. I did use it once for tiny 3" x 3" lights and it worked well.

Have a variety of small to medium size brushes on hand, try out two or three and use the one that gives best results.

Best Advice from the Pros:

Long Life. "The length of service life is controlled more by the methods and techniques used than by the products used. My own current shop standard practice is allow oil-based paints and putty a longer time to dry and cure. I use Sarco Type M for glazing in the shop, and Sarco Dual Glaze for glazing sash in place. About a third of the time I use other methods and materials for their special characteristics to serve the needs of special conditions for specific windows and projects. I have Allback paint and putty in 6 years of field testing and it seems good, but I'm not using it on whole projects yet. DAP 33 should only be used if you can't get anything else. If you are using DAP 33 you should be looking for something else." --John Leeke, Portland, Maine

Speed. "When training someone new to this, I emphasize that speed will come with experience. Technique is learned by doing. Start by concentrating on getting a good look. The technique, and the speed, will come naturally." --Steve Schoberg, window specialist, Plymouth, Indiana

The paint/glazing schedule above seems to work well for many people in many locations around the country. There are others that work as well or better.

Which paint/glazing schedule is better than another? This mostly depends on the methods you use, the micro-climate at the window and the general climate in your area. The only way for you to know for sure is to do a side-by-side field comparison. Do the left side of a lower sash one way and the right side another way. Keep good written notes on your methods and materials. In a few months or a few years you will know for sure which is better, for you, for the type of windows you work on, for the materials you can get.

Many window specialists have built "warming cabinets" or "drying rooms" to control the drying of their paints and putties during cold winter months and humid summer weather. They create a micro-environment with heaters, dehumidifiers and fans in order to speed up the work. However, speeding up the drying and curing rate of traditional materials like the drying oils too much will often give a shorter service life. Slower drying and curing rates extend the service life.

Information Resources:

U.S. Army Construction Manual, Glass:

Paint testing manual: physical and chemical examination of paints, varnishes ..., by Sward, chapter 8.5 Putty, Glazing Compounds, Caulking Compounds, and Sealants.

Let us know the methods and materials you use for painting and glazing sash. Click on "Post Reply" above or below to ask questions or leave comments.

Copyright 2007-2012 John C Leeke


by hammer and hand great works do stand
by pen and thought best words are wrought

Last edited by johnleeke on Sat May 24, 2014 10:01 am; edited 101 times in total
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Site Admin

Joined: 20 Aug 2004
Posts: 3009
Location: Portland, Maine, USA

PostPosted: Sun Jun 10, 2007 8:00 pm    Post subject: Glazing Sash Story Reply with quote

The Singular True and Universal Secret of Glazing

This week I'm turning to some window work here at my house. Nancy, one of my
former interns, is returning to help me out; and, in the office I'm writing
about windows. While there's plenty of real work to do, I think there is time for a story.

Nancy and several of my readers want to know how to glaze windows without making such a mess, getting putty all over your hands and smudging up all the glass. Is it possible to mask off the glass and wear gloves? Is there a happy medium?

Yes! There *is* a happy medium. I'll tell you a little story about where I
my happy medium and then I will tell you the Singular True and Universal
Secret of Glazing, so you, too, can find your happy medium. I learned The
Singular True and Universal Secret of Glazing from an old geezer of a
glazier who worked at a sash factory over in New Hampshire for 40 years or
more. Join me now, in my own shop out in the barn of my 1899 Victorian
here in Portland, as I prepare to perform the amazing glazing....

I use traditional knife-grade linseed oil and whiting putty. First I set the can of putty in the sun or next to a radiator for a day to
warm up so it is pliable and easy to use. If it is a fresh can (just a few
months since it was manufactured), it is usually consistent from the top to
the bottom of the can, and I just start using it right off the top. If it is
older, say from last year's stock (like you might get if you buy it in the
late fall or winter), or a partially used can left over from last season,
there might be a skin or cake of hardened putty on the top, or oil may have
separated out of the putty. I dig it all out of the can and dump it on a
cut out any skin,
caking, or lumps; and knead the oil back into the mass of putty until it is
smooth and even. Then I put it back in the can and rap the can on the floor
a few times to knock any air out of the bottom of the can. Pre-conditioning
the putty like this seems to loosen it up making it easier to work with and
tool into place. The loosening effect seems to last for several weeks, until
the putty "stiffens up" again.

We might talk a little about the temperature of putty. Cold: off the shelf,
room temperature--good for storage. Hot: heated up by setting the can in the
sun or next to the radiator for a few or several hours--good for re-mixing.
Cool: hot putty that has been mixed and kneaded and is cooling off--ready to
use. Warm: cool putty that has warmed up a little due to handling and
tooling as it is placed in the glazing rabbet.

I make putty easier to spread out and tool by controlling the temperature,
never by adding oil, mineral spirits or terps. The manufacturers have
developed their formulas to give certain service life characteristics.
Changing the formula of the putty by amending it with the addition of
ingredients will change the performance. If you are confident you know more
than the manufacturer's chemists then adding ingredients could be good. If
you glaze a lot of windows and go back in later years to check up on the
results you might know how to make the putty work better. With that said I
must admit I have tested out some of these additives but never discovered
advantages that were worth it. It takes an incredible
amount of time and effort to thoroughly mix anything into a compound as
thick as glazing putty.

When glazing I use the three-step Place/Pack/Tool method and work with bare hands. I keep my "on-hand" (left-I'm a lefty)
clean for handling the sashes and the putty knife. (this would help you
control your mess) I knead and place the putty with my "off-hand." My
off-hand is stronger and less coordinated, but this works for me because all
of the initial putty placement is done only roughly.

First I lay a work rag on the bench and sprinkle some whiting on it. Whiting is dry powdered chalk (calcium carbonate).

I pat my hand on the whiting rag, grab a lump of cool putty (cool putty sticks to your hand less than warm or amended putty) about
the size of a tennis ball or even a little more, roll it lightly on the whiting rag, and distribute it quickly
and roughly into the glazing rabbet, working the putty into the rabbet
with my thumb, or the ball of my thumb, feeding the putty to my thumb with the rest of my fingers. There may
be a few skips, a few lumps, but the putty is generally distributed around
the rabbets for each light and the whole sash.

Not much putty sticks to my hand because it is not in my hand for very long, perhaps just 20 or 30 seconds.
As you notice, I don't roll out little snakes of putty. I use the putty
knife which does the same work more efficiently and effectively.

When laying in the bedding putty, I run the putty knife along the rabbet,
spreading the rough putty evenly along the bed of the rabbet. It doesn't
have to
look good, just spread it out continuously along the bed and a little up
onto the side of the rabbet. Then I bed the glass pane into the putty.
Actually the pane beds itself, as I lay my hand flat on the pane I giggle it
sideways a little, which helps the putty flow--jiggle, jiggle, jiggle,
for about a minute. Don't press down, the glass might break. Then I set the
glazing points.

When laying in the top putty, I roughly distribute cool putty as before.
Then I use the putty knife to firmly pack the putty into place with short
strokes that are perpendicular to the glazing rabbet. A little sideways
wiggle of the knife during each stroke helps "relax" the putty letting it
flow into all the little nooks and crannies. The purpose is to bring the
putty into intimate contact with the glass and wood deep within the rabbet.
The putty still looks rather rough and uneven on the exterior. I move on to
do this to the rest of the lights in the sash. This gives the putty several
minutes to "bond" to the surfaces. During this time a little of the oil in
putty seeps out from between the particles of calcium carbonate and wets the
primed wood and glass surfaces helping the mass of the putty adhere to them. This prevents the
putty from lifting out during final tooling. The old geezer glazier
I knew in New Hampshire didn't bother with this extra step of
perpendicular strokes. He said this step would slow him down too much. In
the sash factory they carefully control the temperature of their putty and tune its
formulation for best adhesion and workability. (But, wait.
Don't get excited just yet. You are not quite prepared to
accept the fundamental meaning of The Singular True and Universal Secret of

After wiping any putty residue off my hand with a cloth rag, I am ready to give
the putty its final tooling. This is easy to do because I can concentrate on
The putty is adhering well and not lifting away from the glass and
side of the rabbet, to distract me.
I am not fiddling with scooping putty out of the can and onto the sash, or
fussing with putty on my hands--all that is done. I clean
off my putty knife with a rag, which is easy because I keep the sides of the knife polished so it reflects like a mirror. I hold the putty knife perpendicular to the line of putty.
I set the end-edge of the knife just touching the glass.
The end-edge of the knife is parallel with the line of putty, the
the trailing side edge of the knife is just touching the arris of wood at the top of the glazing
rabbet. The leading side edge of the knife is up off the arris about 1/8". I stroke the whole length of the rabbet three times, keeping the
whole end-edge of the knife on the glass, and keeping the flat of the knife
on the arris. Each stroke
further compresses the putty and refines its shape into a single flat plane:
first stroke, compress the putty and trim away most of the extra; second
stroke, lift
the knife handle a tiny bit to bring the edge of the putty in line with the edge of
the rabbet on the other side of the glass; third and final stroke, smooths
the final surface; and
at the end of that stroke, I smooth out the corner of the glazing by lifting
one point of the blade off the glass and then trailing the other point up
the corner of the putty. (Well, perhaps some things are easier shown in
Repeat for each line of putty around the light, and each light of the sash.

To remove any scraps of putty from the glass or the face of the sash I mop
them up with a little lump of warm putty. Then I'm ready to glaze the next

I like to have a certain very slightly rounded and worn shape
at the very corners of my putty knife--I'll have to take a look at that on
this coming round of window work to see exactly what it is and why it works

So, there you have a few of the little details and subtle nuances of the
work. We are splitting really fine hairs here. Is it worth it? My motto is:
Always Do Best Work. For me, this means every time I do any task I must
remember what I have done, and then do
it a little better. Window after window, each pane of glass is glazed in
there a
little better than the last. To keep getting improvements I must pay
attention to finer and finer details. Over the years it has paid off for me.
Is paying attention to all these little details worth it to you? You will
know the answer to that when I tell you The Singular True and Universal
Secret of Glazing, which I am just about to do. Are you ready to actually
receive The Singular True and Universal Secret of Glazing? I think you need
have to have at least a little putty under your finger nails, to be truly
ready. I can wait if you have to go back out to the shop to dig into that
can of putty...

OK, OK, here it is: The Singular True and Universal Secret of Glazing. The
glazing geezer told me this after everyone had left the glazing shop for the
day. The shop was dark except for a spot of light that encompassed the glazing bench and the two of us. I watched him glaze a few more sash. Finally I broke the silence to ask, "How do you do it, bedding panes of glass in perfect lines of putty day
after day, year after year, decade after decade?" He stepped up to me and held his putty
knife by it's rosewood handle, pointing the blade up to the heavens,
slowly turning its steely edge between his eyes and mine, as its polished sides glinted in the glare of the bare light
bulb hanging above.
He looked me straight in the eyes,
and said, "I will tell you The Singular True and
Universal Secret of Glazing, but you must promise to only tell those who
will become truly good glaziers." I cupped both my hands around his putty
glazed hand that held this time worn tool, and solemnly promised,
"I swear it." Then he whispered, his
words slipping past the thin blade of the knife like all the putty
had done over these past decades, "The Secret is in the
details that you can't see or feel. I like to work after hours late into the
when the shop is still and quite. I listen to the putty and it tells me by a
certain 'squisssssssshhh...ah...ssshhiishh' when it is content to be
perfectly wedded to the wood and the glass."

"And besides, if it is not so perfect, I just scoop it outta there
and do it over. Who's around to tell the diff?"

Ha! We both grinned as he finished up the sash. We walked over to the door. He put out the light, and, as we stepped out into the frosty evening, he locked up
the shop, securing The Singular True and Universal Secret of Glazing into
the darkness of the glazing shop for one more night.

If you have any glazing secrets you want to share, click on "Post Reply" above or below.

John (with no strain, he sets the pane) Leeke

Last edited by johnleeke on Tue Mar 24, 2009 10:13 am; edited 1 time in total
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Site Admin

Joined: 20 Aug 2004
Posts: 3009
Location: Portland, Maine, USA

PostPosted: Sun Jun 10, 2007 8:08 pm    Post subject: Painting Sash Story Reply with quote

Painting Sash Story
It is easy to paint sash if you use a good brush and know how it works. A
high quality sash brush has a good solid pack of bristles set on an angle.
Think about how a brush works. The long thin spaces between the bristles act as reservoirs that hold the paint. The fuller the reservoirs, the easier the
paint will flow back out onto the surface you are painting. Fully load the
brush with paint, working the paint into the depth of the bristles and
filling the bristles with paint all the way up near the ferrule. Dip the bristles into the paint, then slaps the side of the bristles back and forth on opposite sides of the inside of your paint pot. To prevent
drips, tap the tip of the brush on the inside of your paint pot. Do not
scrape the side of the bristles on the lip of your paint pot, this just
takes paint from the reservoirs inside the brush that you just spent all that
effort to get in there. During a brush stroke the paint leaves the ends of
the bristles and capillary action transfers more paint from up inside the
brush down along the bristles to their ends. (some of us will forget the
word "capillary," so let's just call this the "Suck" effect) It takes a
certain amount of time for the suck effect to work. How long? A little
longer than you think. A slow stroke allows the paint the time it needs to
flow out of the brush and onto the glazing. One of the reasons the bristle
ends are set on an angle is so there are more bristle ends to transfer the paint to the
surface more readily (also to reach easily into the many corners of the
sash). Now that you know how a sash brush works, you know that you must
brush with the ends of the bristles touching the surface, not with the sides
of the bristles laying flat on the surface. It also helps to know a little
about your paint. Contemporary "latex" (water-borne acrylic resin) paint is
formulated to be "thixotropic." Ketchup is thixotropic--it tends not to
flow, but once it start flowing it flows more easily, until it comes to
"rest," when it tends not to flow again. (This is different than liquid
water, for example, which tends to flow the same all the time. I know I
won't remember the word "thixotropic," so let's just call this the "Ketchup"
effect.) So, once you get the paint started flowing out of your brush it
tends to flow readily, and when the stroke ends it tends to stay in the
brush. You may ask, "Does oil-base paint flow like this? I state the
obvious: "Oil paint is not Ketchup!"

Paint the surface of the putty first and then paint the face of the sash. Do not start your stroke right on the glazing because it is too difficult to get the paint to begin flowing without deforming the soft surface of the glazing. Do not paint the face of the sash and then start a separate stroke on the glazing, because you will have depleted the reservoir and the "Ketchup" effect interrupts the "suck" effect within the
brush. Paint a couple of short stroke on the face of the sash to puddle up a little paint there. Then with one stroke draw that puddle along and continue the stroke down onto the surface of the glazing. Make a nice slow stroke along the glazing. SLOW is the key that not only gives the brush time to work, it also gives you time to keep track of the edge of the paint as you non-nonchalantly lap it onto the glass about 1/8". It is easy to ease this edge of the paint over onto the glass, because all the outer bristles along that side of the brush are gliding right along to help you out. The valley between the glass and the putty tends to keep the bristles aligned right at the edge of the putty. Do not try to "draw" the line with the very toe of the brush, there are only a few bristles there and they cannot be expected to do all that work themselves. Hold the brush so all of the ends of the bristles are on the surface of the putty.

While the stroke is very, very slow, the painting of the glazing over all is
no slower than many fast strokes because only one, or rarely two strokes are
needed. Slow down and let the brush help you paint faster!

Areas to paint:
I usually don't put top coat paint on the margins of the face of the sash stiles that would rub on the parting bead or stops of the frame. This helps prevent stuck sash in the future.

Surface of glazing wrinkles up:
I also did one sash for a
neighbor, but it only set for two days and I gave it one coat of oil primer
and one coat of oil-based house paint the next day. The painted surface
wrinkled right up like yours, and I expect will stay that way. It happens
because some of the solvents from the primer and paint go into the outer
layer of glazing putty and expand it, causing the wrinkles, then the top
coats of paint set up in the wrinkled shape before the solvent has a chance
to escape.


by hammer and hand great works do stand
by pen and thought best words are wrought

Last edited by johnleeke on Sun Dec 21, 2008 11:40 am; edited 1 time in total
Back to top
View user's profile Send private message Send e-mail Visit poster's website

Joined: 23 May 2006
Posts: 73
Location: Western Pennsylvania

PostPosted: Tue Jun 19, 2007 2:34 pm    Post subject: is waxy preservative paintable? Reply with quote

I read the reference to painting "waxy type" preservatives like Thomsons water seal, but I thought they would not hold paint.

What preservatives do you recommend for application where they will be painted?
Back to top
View user's profile Send private message
Site Admin

Joined: 20 Aug 2004
Posts: 3009
Location: Portland, Maine, USA

PostPosted: Tue Jun 19, 2007 4:32 pm    Post subject: Reply with quote

I read the reference to painting "waxy type" preservatives like Thomsons water seal, but I thought they would not hold paint.

What preservatives do you recommend for application where they will be painted?

As it says above, "Apply >>paintable<< water-repellant". Be sure it says "paintable" on the label.


by hammer and hand great works do stand
by pen and thought best words are wrought
Back to top
View user's profile Send private message Send e-mail Visit poster's website

Joined: 23 May 2006
Posts: 73
Location: Western Pennsylvania

PostPosted: Tue Jun 19, 2007 5:29 pm    Post subject: Reply with quote

Are there particular brands or types you like? I've not really been able to find anything locally that says it is "paintable" (which is why I asked the question). It's probably available, if I knew a particular brand to look for.

Back to top
View user's profile Send private message
Site Admin

Joined: 20 Aug 2004
Posts: 3009
Location: Portland, Maine, USA

PostPosted: Sat Jun 23, 2007 9:29 pm    Post subject: Reply with quote

Are there particular brands or types you like?

It's hard for me to talk about specific brands or products because they change their formulas so frequently that any I recommend might be wrong. Just get a small amount, test it by applying some to bare wood, let it dry and see if it feels waxy/slippery, or tacky/sticky.

If it doesn't say "paintable" on the can it probably isn't.


by hammer and hand great works do stand
by pen and thought best words are wrought

Last edited by johnleeke on Sun Jun 24, 2007 6:27 pm; edited 1 time in total
Back to top
View user's profile Send private message Send e-mail Visit poster's website

Joined: 11 Feb 2005
Posts: 786
Location: Hawley MA

PostPosted: Sun Jun 24, 2007 6:54 am    Post subject: Reply with quote

john.....keeping in mind that you may not want to recommend one product or manufacturer over another, can you name one water replellant you have you used in the past few years that HAs worked and one that HAS NOT worked?

woodturner...make a visit to and check out woodlife classic, it is a paintable preservative and repellant...i have not used the product but, after reading the technical data sheet, it sounds like a product you may want to try.....

Back to top
View user's profile Send private message Send e-mail

Joined: 23 May 2006
Posts: 73
Location: Western Pennsylvania

PostPosted: Tue Jun 26, 2007 9:05 am    Post subject: Reply with quote

Thanks, Jade, that product does sound like it would work. I'll check around to see if it's available locally.
Back to top
View user's profile Send private message
Preserve This

Joined: 01 May 2007
Posts: 18
Location: Holden, MA

PostPosted: Sat Jul 21, 2007 6:27 am    Post subject: paintable preservative Reply with quote

Just to let you know, I too was interested in some sort of paintable preservative. I tried Jade's link above, read the description and liked what I saw. I ordered a can from the online link (no luck finding it locally) and it arrived within a week. Opened it up...looks like milk, paints like water and 9 days after I "preserved" the new sash that I hasn't rotted away yet. So I took that as a good sign. Although I guess the proof will come if the sash is still here in 125 years! Check back with me then and I'll let you know how it's holding up.
Back to top
View user's profile Send private message

Joined: 28 Apr 2008
Posts: 10
Location: Northeast Texas

PostPosted: Mon Apr 28, 2008 1:39 pm    Post subject: Reply with quote

My first attempt at glazing this morning has not gone well. I am working on 6 over 6 farmhouse windows. I have removed all paint, sanded, treated with CPES epoxy sealer, repaired/replaced sashes and muntins, re-sanded, and painted with Zinnser Cover Stain oil-based primer. Unfortunately, the only putty I can get in this area is Dap 33. I bedded the glass into acrilyc latex primer. I took all the putty out of the can, kneaded it and pressed it into the rabbet. The glass side of the rabbet is 3/16 inch and the other side is 1/2. When I run the putty knife over the glaze, it pulls loose from the glass and wood. I tried a little thinner for lube and it helped some, but it still appears that the putty is not sticking to the primer. I ended up taking it all off and putting it back in the can. Is the putty supposed to adhere to the surface upon contact? Should the primer be sanded? Wrong primer? Longevity is more important to me than looks.
Any suggestions will be appreciated.
Back to top
View user's profile Send private message
Site Admin

Joined: 20 Aug 2004
Posts: 3009
Location: Portland, Maine, USA

PostPosted: Mon Apr 28, 2008 4:02 pm    Post subject: Reply with quote

Unfortunately, the only putty I can get in this area is Dap 33.

You should be able to get DAP 33 to work.

Your procedure and materials sound OK up until:

I bedded the glass into acrilyc latex primer.

By "acrylic latex primer" I'm assuming you mean primer intended as a coating before painting. If you actually did apply liquid primer in the glazing dado, then immediately laid in the glass, this could be your problem. the primer may be seeping up onto the wood and glass keeping the putty from sticking. Usually the glass panes are bedding in a thin layer of putty or glazing compound, such as your DAP 33. Please confirm what you are bedding the glass in.

Also, when you press the putty into place, force it in there with a putty knife using strokes perpendicular to the line of putty, getting it in there contacting all the wood and glass surface. Let it sit for 8 or 10 minutes before tooling. This lets the putty's oil creep out from between the particles and adhere to the glass and wood. Then do your final tooling.

Here you can see a little video of this putty tooling technique:


by hammer and hand great works do stand
by pen and thought best words are wrought
Back to top
View user's profile Send private message Send e-mail Visit poster's website

Joined: 28 Apr 2008
Posts: 10
Location: Northeast Texas

PostPosted: Mon Apr 28, 2008 4:28 pm    Post subject: Reply with quote

Thanks for the reply. I meant to say that I bedded the glass into acrylic latex caulk. I got this idea off the Yapp site. I pushed the 33 in with my fingers but not with putty knife and did not let it sit before tooling. Is the 33 supposed to just lay there and gradually adhere to the wood/glass as it cures or should it adhere within the 8-10 min wait time? I will try this again tomorrow. I think I could do a better job if the glazing compound was creamier.
Back to top
View user's profile Send private message
Site Admin

Joined: 20 Aug 2004
Posts: 3009
Location: Portland, Maine, USA

PostPosted: Mon Apr 28, 2008 5:01 pm    Post subject: Reply with quote

OK, sounds like you are all set on the bedding.

One of the problems with DAP 33 is that is is inconsistent from batch-to-batch, can-to-can. I don't use DAP myself, but this is what everyone says about it when I ask at my workshops and training sessions. You may have a batch that is to thick to stick.

You might add a few drops of boiled linseed oil (2 or 3 drops in a fist-full of putty) more is not better), kneading it in well, adding some again until you get a consistency that works for you. If you are glazing a lot of sash I would look for another putty. If you want the "real" putty, get Sarco Type M, see discussions on buying Sarco here in the Windows section of the Forum for sources by phone and mail order.

Also, it occurs to me that your putty knife may be the problem. It needs to be clean and smooth, very smooth. My Hyde putty knives are so smooth they are shinny, reflective like a mirror. If yours is dull, try buffing it up with 0000 steel wool.


by hammer and hand great works do stand
by pen and thought best words are wrought
Back to top
View user's profile Send private message Send e-mail Visit poster's website

Joined: 28 Apr 2008
Posts: 10
Location: Northeast Texas

PostPosted: Mon Apr 28, 2008 5:51 pm    Post subject: Reply with quote

I bought the Dap at a home depot. I had second thoughts when I blew the dust off all the tubs. It was pretty stiff except for the outside 1/2 inch. I am using a new Hyde 2-in-1 v-shaped glazing tool. I will try mixing in the Linseed oil tomorrow. I am currently working on four windows with 9x12 panes but will have about 6 more in the future. I have been unable to download the video (slow dialup).
Back to top
View user's profile Send private message
Display posts from previous:   
Historic HomeWorks Forum Forum Index -> Windows & Doors Goto page 1, 2, 3, 4, 5, 6, 7, 8, 9  Next 
Post new topic   Reply to topic All times are GMT - 5 Hours
Page 1 of 9

Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum