Historic HomeWorks Forum

[johnleeke]

This discussion is for the development of a standard guideline for wood-epoxy repairs. This is the first technical standard we are considering.

Here is a brief description of some methods and materials:
http://www.historichomeworks.com/hhw/library/OHJEpoxy2004/OHJEpoxy2004.htm

You can find many more details on the methods in the Wood-Epoxy Repairs Report:
http://www.historichomeworks.com/hhw/reports/reports.htm#Wood-Epoxy%20Repairs
(download the sample pages)
and the Save America's Windows book:
http://www.historichomeworks.com/hhw/reports/reports.htm#Windows

One important thing to keep in mind is that it's the wood that's important, NOT the epoxy. This is a wood repair method that uses epoxy materials, and NOT a way to sell and use epoxies for the repair of wood. Perhaps a subtle distinction, but important. Wood first, then epoxy.

Steve Schoberg writes, and Jade agrees:
>>One of the traps in the window restoration business is to rely on epoxy too much as a cure all for rot of varying degrees. I think it's very important to look at ourselves as craftsman and non goopers. Anybody can purchase epoxy goop, mix it up and slap it in and around every nook and cranny of a loose sash to make it look good. But thats not restoration...Do basic repairs, with as much natural products and techniques is possible, which I take as don't be a "gooper". That means continue learning different techniques of wood repair and milling, unless you already have these skills. In that case always be watchful that you don't fall into the the gooper trap. Epoxy definitely has a secure place in window restoration, but its not a cure all.

Here's an example: I too don't think Epoxy should be used to build a tenon or buildup a badly rotted rail that should be replace. However, I have repaired a tenon by doweling through the mortise and into the rail and then filling the areas in the mortise around the dowels with Epoxy. I qualify this procedure when the rail is in good condition with the exception of the tenon. <<

Bob Yapp writes:
>>In regard to "gooping" with epoxy I think there have been some good comments. I use and teach the use of epoxies in a very sparing way. However, I find their use indispensable and critical in retaining original materials which is based on the Secretary of the Interiors Standards. Epoxies should never be used to create any structural part of a window sash ie tenons etc. I use and teach using old growth wood to make structural repairs. Let's not forget that epoxy has a 20 plus year track record of successful use when applied properly. <<

[johnleeke]

Steve Schoberg writes:

Is it feasible to suggest a maximum percentage use of epoxy on any given sash to be restored?

[johnleeke]

One thing I have learned doing wood-epoxy repairs for more than 30 years is that the epoxy in the repair is essentially impervious to moisture and can trap moisture in the wood next to the repair leading to fungal decay.

The only exception to this that I have found is very small wood-epoxy repairs at a weathering or drying surface of less than 1/4" to 3/8" wide by 1" or less deep. With these small repairs excessive moisture can effectively migrate around the repair and still leave the weathering or drying surface of the wood.

The internal volume of the wooden part that is repaired must be treated to prevent fungal decay. The only type of treatment I know about that actually works is a chemical one, migrating borate preservative (such as, but not limited to, BoraCare). It is also wise to treat the exterior surfaces of the wood with a water repellent to help prevent moisture buildup within the wood. There are several paintable water repellent preservatives on the market, or you can mix your own according to a proven standard recipe.

So, I propose this as a standard:

Whenever a wood-epoxy repair method is used and the repair area is greater than 3/8" wide x 1" deep as measured at the weathering or drying surface, a chemical preservative treatment should always also be used to protect the entire volume of the wooden part that is repaired.

[johnleeke]

The national Window Preservation Standards have been published and are available right over at the Window Standards website:

www.WindowStandards.org