Waterproofing Wood

Best solution for waterproofing wood - Free recipe

Do it yourself waterproofing wood solution that is practically free.

How To Permanently Waterproof Wood For Pennies Per Yard.

You're going to love this!

I'm going to reveal a little secret I discovered about waterproofing wood or any porous material including concrete. This technique will waterproof any porous material where the exact finished color is not stickling point. And it uses materials commonly found in any do-it-yourself garage.

This waterproofing recipe will use a simple solution of polyester resin and acetone. These simple, everyday products are available at:

  • Better hardware stores (probably not HD)
  • Tap Plastics
  • Boat shops


You can use it on your patio deck, wood boat internals, any woodwork that needs waterproofing. You might even find this ideal for your garage concrete, although I haven't used it for that myself.



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It is not preferred for applications where the wood stain color is important. You will not have control over the outcome color. But! You can always test - test on scraps or test where it wont show. Testing this sealing system is one of the best things you can do for yourself to get a feel for how it performs, how it will look, how it will flow - but more on that later...

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 also why a finishing resin must be sanded or cleaned with an acetone wipe before painting. The wax must be removed or you might have adhesion problems.


Laminating resins on the other hand, contain no wax, and will remain tacky, but requires 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.


And its not to say that some of the better products couldn't out perform the big name brand or even my own recipe for that matter.


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. You don't need to worry about the wax because we are penetrating wood, not coating it - go ahead and use the more commonly found waxed/finishing resin (besides, the acetone in your next coat will remove any wax anyway. 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 calculating 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.





I did read your "recipe" and it looks like what I need. I like to waterproof the exterior wood sills on my screened in porch and would like to find out if your "sauce" can be used for that purpose? Would it span small cracks such as two pieces of adjoining wood stops? Can I stain the surfaces after your "sauce" dries? Using either oil base or latex stain. Your response is much appreciated.



Done correctly, this sealing method will *not* span gaps. It is designed to penetrate the wood pores, and seal them. If you need to fill gaps, you can use a thicker (less acetone) mix, but polyester resin does not do well with build-up, and should not be used for that purpose unless your voids are pin-sized.


Polyester resin is very strong when used with a sub-straight like fiberglass, or in this case, the wood being sealed. But build-ups of polyester resin alone are extremely brittle, and best avoided.


But!, that's not to say that it can not be used to fill gaps - it can when mixed properly with a nifty little thing called micro-balloons. A micro-balloon / resin mix will make for a very nice gap filler that is also very workable and sand-able but don't use it where strength is needed in a gap filler - use epoxy and micro balloons for that.


Moving on - it sounds like finish color is of concern. If micro balloons / resin are used to fill a very large void, then it can affect the color - that area will appear kinda white. But what you describe sounds very minimal, and probably would fill the gaps you've got without affecting finished color - just trowel the micro-balloon mix into the voids as the final process, sand it out, and finish as you wish.


Now for staining. You will not be able to stain after you seal. That's what you want. You can paint, but stain will not take. Stain before you seal, but beware that sealing will wet the color of the wood quite a bit. Test, test, test - once you have your ingredients, and a hand-full of wood scraps, apply stain and sealant to samples until you have a good feel for what the sealer will do to the color, and how much stain to use prior to sealing to get the finished color you want.



Your water proofing is very interesting. I'm restoring a hundred year old house and am getting ready to paint it.


An article from a painter suggests:

        Strip down to bare wood
        Water proof
        Oil base primer
        Latex paint


I've been thinking about Th*****ns water sealer but like your idea. Do you think polyester resin and acetone as good or better than Thom****s? If so do you have name brands and locations you recommend for the products?



T****sons was one of the name brands I tested against and got awful results from. Facts is facts - and my test pieces showed indisputable signs of water penetration after application as instructed - dismal performance!


Having said that, and given the amount of coverage you're looking at, its definitely worth the effort and expense to buy a small amount of the top name brands and apply each to a test strip of wood according to instructions (preferably the same type of wood you plan on using in construction). See if any of them really do repel water drops - does prolonged exposure to water droplets discolor the wood (all be it temporarily), or can you wipe away the droplets after an hour and see no sign at all of penetration at all. In my opinion, T********s isn't up to the job.


The downside to using resin is that depending on your location, it might not be so easy to find - plus I have no exact mixing proportions for you - you don't need exact proportions, the descriptions in the article are sufficient, but a lot of folks are uneasy without exact proportions.


You can get your Acetone at most hardware store. But these places aren't so good for resin - they tend to sell resin as 'boat patch mix' or some silly thing, and they certainly won't distinguish between laminating resin and finishing resin.


In the San Jose Bay Area, we have a chain called Tap Plastics - good source for resin. If you don't have this chain near you, the best thing to do, is look in the yellow pages under 'fiber glass' or similar, since this is the most common use for polyester resin. If you have no plastics/fiberglass shops near by, then hopefully you have some good boat supply shops - an equally good source. If not, then you'll need to figure something out.



I've never used these products before, are there particular brands I should use? Also, what is used as the catalyst or does it come with the resin?



There's not really any brands I can point out. Your best bet is if you have a Tap Plastics in your area, they will have it. And better boat shops in the area will have it. You can look in the yellow pages for fiberglass and those stores will have it.


The catalyst - polyester resin catalyst, isn't usually packaged with the resin, but it will be located nearby - a small x oz plastic bottles or so. You'll want plenty of catalyst because your thinning the resin, but that's all in the article.


If you've never worked with it, then do become familiar with sealing some wood scraps and observing the penetration as described. Observe the resulting beading after allowed to dry - coat again if indicated.




How many coats of the thinned stuff would I need to apply--to insure that those exposed plies are waterproof?



It depends on the progression from thick to thinner. Four coats tops should be sufficient to have several very thin layers, and several slightly thicker layers - use the droplet test to measure your progress.




What are the exact measurements of resin / acetone / catalyst I should use for each coat?



I'm not budging on this one


The important thing to understand is that this is a very forgiving process so exact measurements are never given - to say 10 to 1 does not mean 10 to 4 wouldn't work just as well. The descriptions of thickness are all that's needed for a very successful application.


Above all, test on some scraps - find the thicknesses I describe, notice the tack, try the droplet test. Hit it with finishing resin and then try painting. You'll see how forgiving and easy it is, and you'll be ready to go on the real thing.



Any recommendation on application of your waterproofing concoction? Will a compressed air sprayer be able to spray your stuff or will the resin plug up my gun? Do you know how this stuff holds up to sunlight?



That's one to ponder. On the one hand, resin is about as sticky as anything. But on the other hand, it's so thinned out, that it just might work. On the other hand, the acetone might melt any plastic or rubber parts inside your sprayer if there are any. Whats more, since you are thinning the resin with a lot of acetone, and a sprayer will try to atomize the substance sprayed, and given how quickly acetone evaporates, you might just wind up dusting your project with dry or goopy resin micro balls.


No, I don't think that would be a good idea at all. You need the acetone to deeply penetrate the pores of the wood and evaporate leaving behind the light payload of resin. Spraying would defeat this purpose. Brush the solution on or feel free to pour and spread.


Now the sunlight question, I do not know. But I look at it this way - it's a sealing system, not a coating system like paint. It penetrates the pores, it doesn't coat. So long as you keep that in mind, I doubt you will have a problem with sunlight. But, having said that, if you are concerned about sunlight, then by all means, use a final coat of marine varnish or other coating system appropriate for your project



Hi, I have made some window boxes for my flowers and want to ensure they remain waterproof, do you think your solution would work for the interior of these boxes? Would it also be necessary to apply the solution to the outside? thanks



I've heard from several people wanting to do the same thing. It should work just fine because your not coating the wood so much as you are penetrating it. If you're going to plant directly in the box - soil included, then you might want to be do a few extra coats and finish with slightly thicker coats.


Regarding the outside of the box, if the will live outdoors, then it's a good idea. If they live inside, on the window sill, then it's probably not necessary.


One word of advise, if the boxes have any voids or gaps in the joinery, then you'll want to be sure to brush or pour the solution into these, and that it saturates. Alternatively, get a small container of polyester micro balloons. This is an awesome additive and matches its name literally. Mix micro balloons into a normal (non-thinned) batch of resin and catalyst until it becomes the consistency of putty instead of it's normal honey like consistency. Fill your voids and gaps with this, and then start the sealing process.


See, you never want to allow polyester resin to build up - it isn't strong. Filling gaps and voids with resin alone is a bad idea. But when mixed with micro balloons, the resulting putty becomes far less brittle and is a very appropriate material for filling gaps and voids. It also forms and sands like a dream (so to speak)



I would like to waterproof some window sills and put a finish coat of spar varnish over all. I have had problems with mold around the windows and have sanded them bare. I feel that the resin treatment would prevent any farther trouble. I am also working of more ventilation of the home. My question is, How long do I need to wait between coats?



Hi Judy, that's a good, interesting question I haven't heard yet. The acetone which draws the resin deep into the wood will evaporate in minutes. That only leaves a thin saturation of polyester resin to dry - which at this point, I don't think would be a problem if you hit it again withing a half hour or so. When I use it, I'll give it an hour or so between coats. Give it a little longer during your later thicker coats - but again, these should still be thin enough to seat well in an hour or two tops.



Also, no one seem to know the difference between the finished/waxed resin and the laminating/unwaxed type which remained tacky without 'help' (even a friend who has a fiberglass repair business). Home Depot says they have the poly resin, but couldn't tell me over the phone anything about waxed, etc. I will check over the container for info.



Ugh! Forget about Home Dumpo. The Dumpo might arguably be competent at the simple, ordinary, and mundane needs. You don't stand a chance finding any help there.


If you're anywhere near public water ways, you should be able to find a good boating shop - one that's good enough to sell marine grade coating systems (i.e. paint). They won't give that familiar Home Dumpo stare when inquiring about waxed/unwaxed finishing/laminating.


Just make life easy and use the more available waxed/finishing resin. You'll be loading up with so much acetone that the wax wont really matter much.


I had a question which you might be able to answer. I am planning on gluing some pieces of wood together. Would it be better to glue them prior to waterproofing them or do you think that the glue would hold with the same strength on the treated wood? I was planning on using wood glue. Maybe epoxy would be better?



Seal after you're done joining the peices together. The use of wood glue vs epoxy depends on the application. If you've got good wood-on-wood mating surface, then a wood glue will work well - Elmers Weldwood is a superb product for this type of application, and will result in a joint stronger than solid wood. But it doesn't tolerate voids like epoxy will, so if the surface isn't solid wood-on-wood, then go with epoxy. Then, when you seal, go ahead and cover the joint in sealant, and it should last forever.



your question here



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