Instructions for the use of Smith & Co. Epoxy Products

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Sophisticated adhesives, sealants and coatings are two-component systems. One part has to be mixed with another part before they are applied. After a while, a chemical reaction takes place, and what is created is a filler, paint or glue with exceptional properties. It is not possible to obtain those properties by taking some simple thing out of a can.
Each of these two parts, whether they are liquids or pastes, consists of very small components called molecules. The manufacturer designed the system so that the individual molecules of each component would react with each other in certain proportions. That is why the instructions say to mix the materials in those proportions.
If the materials are mixed in different proportions, then some molecules of one or another component are left over, scattered among the molecules of both components that did react together. In that case, the material will be softer or weaker than it should be, or will soften in water when it should not. It might be a gooey mess. It is therefore important to mix the components thoroughly, so that everywhere in the mixture the ingredients are in the correct proportions, even down to the individual molecules.
We make Fill-It parts A and B different colors to make it easy to thoroughly mix the product. When you can see the streaks of different colors you know you must continue to smear, scrape, fold and mix until the color is uniform. The mixing tools themselves must be scraped occasionally. If mixing a paste on a flat surface, the mixing surface itself must occasionally be scraped off. When mixing liquids in a container, mix thoroughly in one container and then scrape out the entire contents into a second container and mix again.
If there are any soft or gooey spots in the final cured product, which is proof that the material was not thoroughly mixed.

Making Coatings Stick Better

All woods consist of cellulose fibers bonded together by a natural resin which acts as glue, Typically seven to fifteen percent moisture is present (chemically attached to the cellulose) depending on average humidity, There is also a varying amount of "sap", which is a complex mixture of different oils and resins. Hardwoods such as oak have different resins than softwoods such as fir.
In order to obtain a good bond between wood and any paint or adhesive, the fibers on the surface of the wood must be strongly bonded to each other and to the adhesive or coating. The surface of wood is microscopically rough, with many surface fibers loosely attached to the bulk of the wood underneath. Glues and the liquid portion of paints can soak into porous wood surfaces. This can produce a paint with most of the pigment on the surface and most of the paint resin soaked into the wood, and such a resin starved coating will soon fail. It can also leave the glue joint starved for glue and hence weakened. Therefore a sealer is important in order to obtain good adhesion between wood and paints. Epoxy resin systems do not readily dissolve water, but Clear Penetrating Epoxy Sealer (CPES) contains a high percentage of alcohol in order to dissolve not only the moisture in woods but also the sap and oils.
The fungus that causes dry rot retains a lot of moisture and inhibits effective penetration of sealers that cannot dissolve water. Mildly dry-rotted areas can be epoxy-impregnated very effectively by CPES since it can dissolve water.
It is not unusual for varnish to peel off of wood in six to eighteen months, even when a top-quality varnish is used. Varnish is highly refined oil-base enamel paint without pigments. Neither varnish. enamel or latex paints are particularly aggressive adhesives. Our epoxy products are very aggressive adhesives.
Now we have a very important concept: If we apply something over a surface to which CPES was previously applied, but before the CPES is (roughly) half-cured, the second material proceeds to cure first, and the resin film of the CPES cures last, gluing down the second material. This is why CPES is such an effective adhesion-promoting primer for varnish.
The particular resins used in Smith & Co. products are substantially derived from wood itself because these particular resins, when they cure, will have a toughness and flexibility that is comparable to the original wood. The fact that the surface is dry to the touch does not mean that the resin is cured. See Product sheets for specific curing times.
The modern use of the word primer has become a non-specific term used broadly and irresponsibly by most paint manufacturers. Literally, a primer was to be the prime coat, or first coat. This derives from the Latin primus, meaning first. Products now available in the marketplace include adhesion ­promoting primers, waterproofing primers used to seal a porous substrate, filler primers, sanding and surfacing primers, corrosion inhibiting primers for metal, wood primers intended to block tannin bleed-through of wood topcoats, moisture-diffusion-barrier primers, and probably others. Adding specific adjectives to the word primer conveys a clear concept.
When sufficient CPES is applied to the wood in one application to completely saturate the wood, a thin film of the mixed resins of CPES is left on the surface. The CPES glues down the varnish, and the ultraviolet absorbers in the varnish protect the epoxy and the wood from degradation by sunlight. From what our customers tell us, the typical life expectancy of a good quality varnish, applied in this manner, is two years or more.
When using clear topcoats such as varnish or polyurethane it is important to know that the ultraviolet absorbers used in all clear coatings are sacrificial. They will eventually die. Therefore, more coats give a longer life. When the ultraviolet absorbers finally "bum out", the ultraviolet from the sun passes through the clear topcoat and attacks both the CPES resin and the underlying wood, breaking down the cellulose fibers. The coating eventually fails as the material beneath it swells and decomposes.
Clear epoxy products are not chemically compatible with ultraviolet absorbers, and so epoxy coatings are not used as clear finish coats.
In pigmented coatings the pigments block the ultraviolet. Because the pigments are chemically stable minerals, they do not "burn out" and so this failure mechanism does not exist. Enamel and latex or urethane paints will therefore last longer than clear urethane or varnish coatings, although high quality clear coatings can last several years. Latex paints, alkyd enamels, urethane coatings and varnish can adhere better and last longer with Clear Penetrating Epoxy Sealer applied to the wood first.
The manufacturers often changes paint formulations. Always do a small test with new product combinations to ensure everything works together.

Frequently Asked Questions

Q: How much of the old paint will I have to remove?
A: Perhaps 95%. Clear Penetrating Epoxy Sealer will not soak through old paint, but if the remaining paint on the wood is in spots smaller than 1/4" ­1/8" the CPES will soak around and under the old paint. It may, however, cause the edges of the old paint to curl up. You may have to sand the wood and apply CPES again.

Q: How much rot do I have to remove before applying the sealer?
A: Whatever can be scrabbled away with the bare finger tips should definitely be removed. Light brushing with a wire brush easily removes badly deteriorated wood.

Q: Do I have to use the sealer first before I use the filler?
A: Yes. After applying the sealer, wait until the wood no longer smells strongly of solvents before applying the filler. This will take at least a day and may take a week, depending on the extent of deterioration and how deeply the CPES soaked in. Do not apply filler on top of freshly impregnated wood.

Q: How soon can I paint the filler? Do I have to prime it?
A: The filler cures overnight and should be sanded before painting. CPES is an excellent adhesion-promoting primer for paint when the topcoat needs a primer, although most primers can be used.

Q: How long is the shelf life?
A: At least a year, if the containers are closed after use.

Q:Can I use it inside?
A: Yes, but you must provide adequate ventilation such as an exhaust fan in the window. It is also a good idea to wear a mask with an organic vapor filter cartridge when working with chemicals or solvents.

Q: Does it meet the Air Quality Management District regulations?
A: Yes.

Q: Will this pass inspection?
A: The inspector usually stabs the wood with a screwdriver to see how easily it penetrates. After proper restoration the repairs will feel the same as new wood.

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This article written by Steve Smith ©2002, All rights reserved.