Waterproofing Wood

Let me reveal a little secret I discovered about waterproofing wood or any porous material such as concrete. This technique will waterproof any porous material where final color is not important to you. And it uses materials commonly found in any do-it-yourself garage.

This waterproofing solution uses a simple recipe of polyester resin and acetone. The same kind of polyester resin you use with fiberglass. You can use it on your patio deck, wood boat, any woodwork that needs waterproofing.

It might not be preferred for your floor, wood floors, or anything with a natural stain finish, but for any exterior waterproofing it is ideal. You might even find this ideal for your garage concrete, although I haven't used it for that myself.

But first, a word about polyester resin

This will be important to understand later on, so don't skip ahead.

There are two types of polyester resin to be found. Finishing resin (or waxed) and Laminating resin (unwaxed). What is the difference? - glad you asked. When you add catalyst to polyester resin, it starts a chemical reaction that generates heat. This reaction, and the heat are what causes the resin to kick (harden).

But polyester resin will not kick fully to the touch (not tacky) without some help. The finishing or waxed resin contains a small amount of wax. The heat causes the wax to raise to the surface and deprive the resin of oxygen. It is this depravation of oxygen that causes resin to kick to the touch without a tacky feel.

This is why a finishing resin must be sanded or cleaned with an acetone wipe before painting. The wax must be removed or there will be adhesion problems.

Laminating resins on the other hand, contain no wax, and will remain tacky, but require no cleaning before you can apply something else - like more resin or fiberglass. Now,,, this is not to say that you cannot get an unwaxed resin to kick. Although I have not tried it myself, I have heard of people using cellophane to finish the kicking process. A bubble free application of cellophane over an unwaxed resin will complete the kicking process. Just peel the cellophane away and your done.

Using this cellophane kicking method you can skip the sanding or acitone wipe to remove the wax layer - a very messy job wether you sand or use an acitone wipe.

Also, you should always strive to use fresh resin and catalyst. This stuff is cheap, so don't trust that old can that's been in the garage for years. Wether you are applying fiberglass or waterproofing wood, use fresh polyester resin and catalyst.

My testimonial - and I'm sticking to it

I once did a test. I took some of the big name brand wood sealant that we've all seen in commercials. I took a scrap of B-C marine grade plywood (that's what the lumber yard sells as A-B grade, is actually a B-C grade specification - go figure) I applied the name brand wood sealant according to instructions on one half, and my waterproofing secret sauce on the other half.

Once dried, I sprinkled water droplets on both halfs. Guess what I observed. On the name brand side, I immediately observed wood discoloration under the droplets, indicating that the water had soaked in to the wood. The big name brand sealant let the water soak right in. Unbelievable. What in the world am I paying for? Unfortunately, I did not do a control test with droplets on wood with no sealant, so I cannot say that the big name brand did absolutely nothing at all, but for my money, it's performance was pretty pathetic.

This is not to say that some of better products featured here would not out perform the big name brand or even my own recipe.

As you might expect, my waterproofing secret sauce performed perfectly. After reapplying droplets for several hours, I observed no sign of water soaking into the wood.

So that's my testimonial, and I'm sticking to it.

Back to the subject of waterproofing wood.

We're going to do several coats, so start with your unwaxed resin (See above). Start with a small amount of resin (depending on project size) and thin it down with 4 to 6 parts acetone until it's almost like thick water. This is the secret, because the acetone will soak deep into every one of the most microscopic pores and fibers of the wood or other material. It really soaks in, carrying the resin with it. It's application is so light and thin, that it tolerates wood flexing without problem. It becomes an integral part of the wood or concrete and it will not crack or separate.

You'll need to use far more catalyst than recommended on the label, so increase the catalyst by the number of parts thinned or more. Don't worry about using too much catalyst with this recipe.

Lets say you're mixing up 1 gallon of this stuff - 4, 6, or more parts acetone to 1 part resin. For the purpose of calcluating the amount of catalyst to use, treat the gallon as pure resin. If the catalyst bottle says to use 1oz for a gallon of resin, then use 1oz for your gallon of waterproofing sauce. Then give it a few more squirts for extra measure - again, excessive catalyst is not a problem when the resin is diluted like this.

Too much catalyst is only a problem when applying thick - un thinned amounts of resin - fiberglass application for example. Too much catalyst can cause so much heat that the resin becomes brittle, and that would be a structural compromise of the resin. We don't have to worry about that here:

• This is not a structural application like resin on fiberglass.
• Our resin is so thin that heat build up is not a problem.

With your first application done, it's time for some more. Mix up more of the waterproofing solution, this time using less acetone, and less catalyst. Apply, and repeat, reducing the acetone dilution each time. You will know when you've got enough coats because you will not see any coloration changes that indicate acetone soak-up is occurring in the wood - wallah! it is sealed.

You're not looking for any thick buildup of resin here, but more appropriately, the thinnest (least brittle) amount you can. You should still be able to easily feel the texture of the wood or concrete. All you've done is get the acetone to draw the resin into the pores of the wood, or whatever material you are waterproofing.

Your final coat should be done with waxed or finishing resin. Or, you can use the cellophane kicking method described above. The cellophane method of kicking resin is nice, because you will not need to remove the finishing wax with sanding or messy acetone wipe. But if you intend to paint, you'll need to sand the surface anyway. Just use the waxed resin and sand the surface when ready.