Sash Spot Paint Maintenance (with Video).
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johnleeke
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PostPosted: Fri May 21, 2010 1:32 pm    Post subject: Sash Spot Paint Maintenance (with Video). Reply with quote

Sash Spot Paint Maintenance

Video: Step-by-step procedure. 17 min.
At minute 6:30 it shows use of the crack tool.

Condition to be Treated: Paint failure in tightly localized spots.

Description: Remove damaged paint, seal loose or open joints and paint. This treatment is suitable for interior and exterior areas of peeling or missing paint. Moisture causes paint to peel. Typical sources are exterior rainwater on the glass above, interior condensation on the glass above and water on the sill. Spot paint maintenance will help seal out the water, keeping the wood dry. Several spots on more that one window can be treated at the same time, achieving an efficiency of scale.

Typical Procedure:

1. Set up for lead-safe operations, which may include working wet during paint removal, surface preparation and clean up.

2. Assess conditions, determine causes, plan work. The paint film may be cracked, alligatored, loose, peeling or missing. Determine the extent of the damage.

3. Hold the sash steady with wedges between an edge of the sash and the jamb of the sash track.

4. Scrape off loose paint with steel scraper. Clean out open joints, especially along the glass.

5. Final lead-safe cleanup, then let the wood dry out. This might take a full day, or use fan, hair dryer or hot air gun to speed up the drying.

6. Pre-treat with oil on all bare wood, soaking more oil into the joints. Let dry for a day. Skip this step if using sealants in joints for step 7.

7. Fill open joints with oil-based putty. Skip this step if using sealants.

8. Prime bare wood surfaces, lapping 1/16" onto glass and lapping just a bit (1/8") onto edge of sound paint. If using sealants work primer into loose or open joints, clean any free liquid primer out of the joints by wiping with thin cardboard. Allow primer to dry.

9. Seal joints between wood parts and between wood parts and glass pane. Allow sealant to cure.

10. Sand lightly, if primer feels rough.

11. Paint, two coats, with topcoat paint, lapping 1/16" onto glass. Allow to dry between coats. Sand lightly after first coat if surface feels rough.

12. Remove wedges. Make sure sash moves freely and is not painted shut.

Materials:
Sandpaper, 100 grit
Putty, glazing compound or sealant
Oil-based pre-treatment
Primer, oil-based
Paint, top coat, oil-based or waterborne acrylic

Quality of Results:

Best Work: Open joints are filled. Paint coating presents a smooth surface and even luster. Paint and primer lap onto glass. Sash moves smoothly.

Inadequate Work: Remaining loose or peeling paint. Paint feels rough or appears uneven. Open joints that are not filled. Sash is painted shut or does not move smoothly.

Tools:
Wedges
Paint scraper
Crack tool
Paint brush

Kits:
Paint kit
Lead-safe kit

Time:
Direct production time: 15 to 20 minutes per spot, over the course of 3 days. "One spot" is any surface work area within a 1' x 1' square area at one location. (not including access, workspace setup (moving curtains, furniture, etc), lead-safe operations, etc.) For a typical lower sash with peeling at both lower joints, that would be counted as two spots.

Click "post reply" for questions or comments.

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


Last edited by johnleeke on Wed Apr 23, 2014 10:37 pm; edited 7 times in total
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TimB



Joined: 03 Sep 2009
Posts: 43

PostPosted: Fri Jun 11, 2010 8:01 am    Post subject: Oil Treatment Reply with quote

John, what do you use for the oil treatment (step 6)? Sorry if this is answered in the video... I don't have speakers!
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Tim Brosnihan
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johnleeke
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PostPosted: Tue Jun 15, 2010 9:13 am    Post subject: Reply with quote

There are two types of pre-treatment,

1. Paintable water-repellent preservative
2. consolidating oil-resin.

In the video I'm using a consolidating oil-resin, in this case it is Allback's Boiled Linseed Oil, used straight. The primer and topcoats are Allback's Linseed Paint. (On the other joint of this sash I used American products as a side-by-side comparison field test. Perhaps I'll post the video showing these other products and explaining the test.)

Paintable water-repellent is suitable for sound wood surfaces. (if waxy paraffin type (Forest Products Lab's WRP Recipe, Thompson's WaterSeal, or similar)

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) Just to confuse us all, there are some combination products that are 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.

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.

Penetrol is an oil-based product made of mineral spirits, linseed oil and alkyd resin 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. After 24-48 hours the treated surface is dry to the touch and ready for light sanding or direct application of putty or paint primer. 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.

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TimB



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PostPosted: Wed Jun 16, 2010 12:35 pm    Post subject: Reply with quote

Thanks John. I assume that the purification process the Allback linseed oils undergo make them less susceptible to the mold and fungal attack you mention below.
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Tim Brosnihan
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johnleeke
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PostPosted: Wed Jun 16, 2010 2:54 pm    Post subject: Reply with quote

Yes, the purification is what makes the Allback linseed oil worth considering. But, I'm still testing and not recommending.

Using a product like Penetrol for this oil pre-treatment is more time-tested.

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by pen and thought best words are wrought
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