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Clear Penetrating Epoxy Sealer, The Science, Technology And Use To Restore Rotten Timber

This article is written by Steve Smith, the chemist behind Smiths Clear Penetrating Epoxy Sealer (CPES), who had been asked to clarify a few matters about his products and their underlying science, particularly about Clear Penetrating Epoxy Sealer™ also known as CPES™.

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Why Clear Penetrating Epoxy Sealer?

I called it Clear Penetrating Epoxy Sealer since 1972 when I first invented it as a pure descriptive name (a product that really does what it says on the tin), but found out after forty years that I could not own a trademark for a simple descriptive name. I found this out when many companies in 2013-14 began selling ersatz products and using some-or-all of that name.

I therefore re-branded (and copyrighted) the name Smith’s Clear Penetrating Epoxy Sealer™, and the label says it is the Original and Genuine Smith’s Clear Penetrating Epoxy Sealer™, and rightly so.

Clear Penetrating Epoxy Sealer. Smiths Genuine

What Is Smiths Clear Penetrating Epoxy Sealer (CPES) Made Of?

The resins are made largely from the natural resins of wood, unlike any other commercially available epoxy product. This gives this material a toughness and flexibility that no other epoxy product has. The resins are naturally solids by themselves, so the fact that the solvents have evaporated and a dry-to-the-touch film remains does not mean it is cured.

The actual chemical curing takes several days (there’s information on the label, and also at the company website) and that’s one of the big differences between the CPES technology and that of other products.

Do you see anything else with a 4-8 hour pot life? As curing takes place over days, not hours, it is easy to have a half-cured dry film for a day or two that will glue down the paint or varnish as it finishes curing. This ability to make paint and varnish really last is covered in MultiWoodPrime The ultimate primer and How to varnish outdoor wood to make it really last.

Is Thinned Epoxy The Same As CPES? Do The Copycat penetrating Epoxies Work?

You can solvent-thin any of the well-known relatively hard epoxy products or even use the recently-marketed generic “Penetrating Epoxy” products and soak it into somewhat soft wood where fungi have eaten away some of the wood fibre content but some of the wood fibres still remain. It may glue those fibres together, but if you stick an icepick into the “restored” area in the middle or at the boundary, the texture of the wood will be “crispy”, as one of my customers called it.

They obviously does not have the flexibility of natural wood, and with time cracks will develop in that area due to the natural movement of the surrounding sound wood. This opens the door to Small Life (Small Life = Stuff that eats wood; mould through bacteria all the way to termites) causing further deterioration. After this treatment, and it’s inevitable failure of course, you won’t be able to do anything except replace the damaged timber.

Are There Proofs Of The Performance of CPES Epoxy?

You can go to Published there is a paper that shows the underlying science of Clear Penetrating Epoxy Sealer. For fifteen years I knew it (CPES) worked based on the continuing testimonials of my customers, but I never knew exactly why. That paper is the result of 10 years of research effort to find out why it works so well.

The paper is complete with time-lapse photographs showing how it selectively wets the deteriorated parts of wood while water selectively wets the sound parts of wood. There are pictures taken through microscopes showing the penetration of Clear Penetrating Epoxy Sealer into single-fibre defects in wood such as where fungi ate. In Section 4 there are mechanical tests showing that treated wood and untreated wood bend just the same.

Are There Competitors To Clear Penetrating Epoxy Sealer?

There is  an open standard for products that others might want to produce that do what Clear Penetrating epoxy Sealer does published on the website. No one has taken up that gauntlet in nearly 20 years. Clear Penetrating Epoxy Sealer is unique, and the solvent / resin formulation is based on actual science. Just thought you might like to know…

 So How Do I restore Rotten Wood With It?

Wood Rot

Rotten wood consists of fibres of wood separated by spaces where other fibres were eaten. The aim in restoring the wood is to glue those fibres together again, to restore mechanical strength, and then to stop the rot from happening again.

My resin system, so much resembling natural wood resin in its properties, glues the remaining fibres back together,and that is why the treated wood so closely resembles natural wood.

All we have to do is get it in those spaces. If there’s no empty space, nothing enters and it all sits on the surface, leaving the wood below still physically weak and thoroughly impregnated with fungal spores, awaiting only the right conditions to hatch, grow, eat more wood and teach their young the same game.

Getting back to restoration, it only makes sense that  if you are going to glue those remaining fibres inside the wood back together, this stuff has to be able to get in, so there must be empty space for it to go into;  If there’s no empty space, nothing enters and it all sits on the surface, leaving the wood below still physically weak and thoroughly impregnated with fungal spores, awaiting only the right conditions to hatch, grow, eat more wood and teach their young.

Dry The Wood As Much As You Can Before Restoring

The wood cannot be waterlogged. It may be above the fibre-saturation-point of about thirty percent, but there has to be some empty space in there, so the Clear Penetrating Epoxy Sealer can get in. Once inside the wood, the solvents evaporate out and carry some of the excess water away.

That’s an important point, and again, very different from any other product on the market. The unique formulation of specialised resins and a carefully engineered solvent-system maximises excess-water-pick-up, and its evaporation leaves a residual porosity resembling the natural porosity of the wood, so the restored wood can still breathe, even though the wood is impregnated in that area.

The impregnation is not with a solid block of dense epoxy, but rather with a very flexible hydrophobic resin system that resembles the natural resin/oil in wood, has large spaces between its molecules so water molecules can easily diffuse through, and gently holds all those remaining fibres near each other. The wood in that area is now restored as best we can.

What Strength Am I Left With?

Tensile Strength

The strength of wood comes from the tensile strength of its fibres, and there are fewer of those remaining. Still, we did the best we could with what we had, and that’s better than a lot of alternatives.

Compressive Strength

The Compressive strength however will be massively improved, if the hardened timber is carrying joists for instance it can be restored to a very high degree.

Prevention Of Further Rot

“Restoration” is a returning towards the original. It won’t be perfect, but if my Clear Penetrating Epoxy Sealer is allowed to penetrate as far into wood as the fungi have eaten and left their spores, that wood will resist further deterioration in that area for a long time. I don’t know how long, but there’s a lot of folks out there that seem fairly well satisfied and I’ve been making this product since 1972.

Does CPES Work?

We have a page of performance tests for penetrating epoxies here.

Where do I buy CPES from?