Window and sill repair and restoration

An easy process for the homeowner, handyman or painter

When old paint cracks, water gets into the wood under the paint. Water comes in as a liquid, but it can only escape as a vapor. One drop of liquid water makes about 1200 drops of water vapor, which is why the wood stays damp a long time in that area.

Rot fungi love damp, warm wood; their spores are in the air, everywhere. The water carries the spores in, they hatch and begin to eat the wood.

When you discover there’s some action beneath the paint, there may be quite a bit of rot already. If this has gone on too long, half the window-sill may actually have fallen off, or the rot may have spread to the vertical parts of the window-frame and the window itself.

It is difficult to get one replacement wood window-and-frame that matches the old one, but there are folks who make exact-match replacements. You may have many such windows on your house, with some rot damage and more in their future.

Repairs as replacements or reconstructions can cost many thousands of dollars or even tens of thousands. This technical note will tell you how to do it for hundreds…roughly a tenth or even much less than the cost of what a tear-out-and-replace remodeling contractor charges.

Restoration can be less expensive than replacement. I invented the Modern Technology That Restores Deteriorated Wood over 35 years ago. I published a Paper about this in 1998. This technology is highly successful around the world. You can learn more in the pages of the Smith & Co. website.

The first step is to remove the old paint and please don’t use some chemical stripper without first reading our literature. Call 1-800-234-0330 to have a packet mailed to you, and at the very least read about The World’s Greatest Primer.


Removal of old paint can easily be done with a palm sander and 50-grit paper, or with a heat gun and a paint-scraper. I personally like a metal-blade putty-knife with a wood handle (and the heat gun held parallel to the handle and aimed down along the length of the blade, to blister up the paint as the scraper is pushed along to remove it). The first time I did that I used a putty-knife with a plastic handle. When the blade got hot, it heated the handle which of course melted. Fortunately, no one was watching me learn that lesson. I then made my own wood handle from a bit of an old broomstick. There are metal paint scrapers with triangular or odd-shaped blades for getting into nooks and crannies.

With the wood mostly bare [a few small flakes of paint remaining in pits and crevices are usually not a problem], we can now do a damage assessment. You will likely find many areas that seem a little soft to the fingernail. These are usually restorable with the Clear Penetrating Epoxy Sealer, so don’t go tearing everything apart just yet. What you remove, you will need to replace with the Fill-It Epoxy Filler. As you poke the wood, you may find soft spots so soft that you could easily remove the material with your bare fingernails. Those areas are far-enough-gone that they should be cleaned out and filled.

Now that you know what to look for, get a very small screwdriver or an icepick, and probe the wood to evaluate its overall condition. You can clean out the bad areas with a screwdriver or wood chisel by hand, or even use a small wire brush to remove what needs to be removed. If you are not comfortable leaving some part, then remove it.

Now that you can see what volume need to be filled, estimate how much filler you might need. There are 231 cubic inches in a gallon of anything; call it 200 in round numbers. That’s a bit over fifty in a quart, or about 25 in a pint. Estimate what you will need.

Don’t continue any farther if the wood is still damp, or got rained upon recently. The wood must be dry so that you can do a good job.

The next step in the restoration process is to saturate the remaining wood with the Clear Penetrating Epoxy Sealer. It runs almost like water, and is designed to impregnate the wood as far as fungi have eaten into it and deposited their spores, even along single wood fibers.

This is the fundamental difference between my Modern Technology and the older methods of repairing rot damage by just digging out what was soft and filling the cracks and rot-pockets with some caulk, putty, fiberglass-repair resin or epoxy filler, and painting over it. Have you ever seen a plug of old filler rising-up under the paint as the wood continued to rot and swell behind the old “repair”? The fungi have left their spores in the wood far, far beyond what you can see as deteriorated. Only Clear Penetrating Epoxy Sealer can find all of that abnormal porosity and impregnate it. See what Smith & Co. customers say about the durability and longevity of their work at the Testimonials and the Testimonials from Professionals.

The Clear Penetrating Epoxy Sealer is a 2-part epoxy product, and it is furnished as two metal cans of Part A and Part B. They mix 50-50, and you can mix up as much or as little as you need. The pot life (working time after mixing) is many hours. Industry-standard cans are pint, quart, gallon cans and five-gallon pails, so this product is furnished as a 2-pint kit, a 2-quart kit, a 2-gallon kit or a 10-gallon kit.

It may seem difficult at first to know how much will soak into the wood, for the porosity is inside and not visible. As a guide, you might find a 2-pint kit quite adequate for restoration of part or all of a window-sill, while a 2-quart kit may be adequate for restoration of the entire window-sill, window-frame and window. Every piece of deteriorated wood is different. As you get further into your job, you will become the expert on just how much material you will need.

With our literature and supplies, you can restore all your exterior woodwork and apply an exterior paint system (preferably an oil-base primer and a latex topcoat) that will still look like the day you did it, many years later. We would like to hear from you. Let us know.

© copyright 1972 - 2009, The Brain Trust, a California irrevocable trust,
reprinted with permission

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