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Penetrating Epoxy
By:Brian C.
Date: 10/6/1998, 12:10 am


I thought I would pass this POST/RESPONCE I had on the WoodenBoat forum about 'penetrating epoxy':


---------------------------------------------------- Original Message:

Posted by: Brian T. Cunningham ( ) Organization:EDS Date posted: Fri Oct 2 17:09:17 1998 Subject: Penetrating Epoxy Message:

I see posts arguing over penetrating epoxy versus regular epoxy. What's the difference? Who sells it? Would it be good on a stich and glue boat?


Subject: Epoxy "apples and oranges" Reply Posted by: Bob Cleek ( ) Date Posted: Fri Oct 2 19:23:49 1998 Message:

If I do any more advertising for Steve Smith's penetrating epoxy, I'm going to start charging him for it... or at least ask for a discount! Penetrating epoxy sealer is a different animal from "regular epoxy," whatever that is. (I gather you are referring to WEST System "googe" made by Gougeon Bros, or similar stuff.) Let me quote from Steve Smith's "How to Fix Your Wooden Boat": "There is no wider variety of properties available in an adhesive system than in those formulated from epoxy resins. There are stiff pastes, viscous liquids, or extremely runny systems." Now, from the same tome: "(Clear penetrating epoxy sealer accounts) for three-quarters of the world's consumption of the sealer. CPES is used to seal wood surfaces prepatory to adhesive bonding, or to obtain higher bond strengths...The sealer is particularly formulated to provide enhanced chemical adhesion to both epoxy resins and polysulfides. It provides a bond between microscopically rough wood surface and the adhesive, which is often viscous and can not penetrate and saturate the microscopic fibres and spaces that make up the surface of the wood....(CPES) consists of an epoxy resin and a curing agent which, when cured, have a toughness and flexibility comparable to that of most woods. The CPES is formulated with the epoxy resins dissolved in a carefully selected blend of solvents designed to dissolve not only the water, but the oils and saps found in woods. The wood is strengthened without making it excessively brittle, and normal expansion and contraction of the wood with changes in temperature and humidity are allowed. An epoxy resin sealer system which does not contain water-dissolving solvents (like "googe") cannot penetrate wood as effectively as this system....When two pieces of wood have been treated the day before with CPES, an adhesive (like "googe") will achieve the ultimate strength of bond between the two members. The sealer has provided a bond between the surface of each wooden member and the bulk of the wood itself. When applying a paint or varnish to wood, the durability of the coating will be exceptional because the paint has a strongly attached, chemically compatible surface to bond onto. Varnish applied over wood which has been treated with CPES has lasted more than three years (I can attest to that!), whereas varnish on bare wood often peels in six to 12 months....when the wood has been treated with CPES a day or two before polysulfide caulking is applied, very high strength, permanently waterproof joints are obtained." So, there you have it, from the horse's mouth. CPES is a two part one-to-one mix that flows like water and has a working life of about 36 hours, but dries tack free in about two. It costs about $75 for a two gallon kit and comes in quart kits too. You can get it from Smith and Company, Industrial and Marine Synthetic Resins and Specialties, 5100 Channel Avenue, Richmond, California, 94804, 415-237-6842. I've also seen it in a slick, retail, non-industrial package for about $100 for a two gallon kit in some chandleries. This stuff is the mother's milk of wooden boat restoration. All the pros in the SF Bay Area swear by it. Don't leave home without it. Mmmm.... maybe I ought to ask Doc Smith for an internet distributorship....


Subject: Oh, and to answer the second part of your question... Reply Posted by: Bob Cleek Date Posted: Fri Oct 2 19:27:55 1998 Message:

Yes, CPES is definitely the ticket for a stich and glue boat, but as you may have surmised from my previous post, NOT AS AN ADHESIVE, which it is not. You put the CPES on your wooden parts and let it cure overnight, then assemble with your tape and thickened "googe." The CPES will provide the best mating surface for the "googe" and also for your ultimate finish coat of paint or whatever. It also stabilizes plywood very well, greatly minimizing, if not eliminating checking and raised grain.


Subject: Oh, and one more thing.... Reply Posted by: Bob Cleek Date Posted: Fri Oct 2 19:31:41 1998 Message:

People may say that you can thin "googe" with acetone or alcohol and make it flow like CPES. This is true, but neither Smith or Gougeon recommend this. The effect may appear the same, as the acetone or alcohol does act as a thinner, but it is not the same stuff as CPES, which has specific solvents for penetrating the wood and displacing moisture and oils. I also suspect that the chemical bond achieved when thinned googe cures is not anywhere near as strong as when used "industrial strength." I would advise against this short cut.


Subject: basics Reply Posted by: Bob Miller ( ) Organization: Reunion Marine Date Posted: Sat Oct 3 2:00:36 1998 Message:

Hi, Brian. Take all that Bob C. said to hart. then remember your household chemistry. The difference between the two(or more) types of epoxie is basicly surface tension. Just like plain water or water with soap in it. One cuts grease, flowes into the poures of the surface and wraps around the permanate structure for good. The other just washes off the surface dust. We do the same thing when we "seal" wood with a material that is "dissimiler" to the top coat in conventinual coatings. I got a sneaking idea that if "Get Rot" got off it's high horse and sold it's product to compeat with Smith, we would have two players! In the real world of your project, take a look at "dynamite Payson" and what he does with the products of the past. I don't trust plastic, but I trust a man who busted his *---* and made a living from the sea , in boats from his own hands. After he comes back from the sea for a few years, you might get the idea that he knows a thing or two about cutting edge tech., and it is not the end all, be all of boatbuilding! How pregnant can you get? Think about it. Bob M.


Subject: CPES Reply Posted by: David Knight ( ) Organization: The Lighthouse Co. Date Posted: Sat Oct 3 17:22:09 1998 Message:

Brian: Many thanks to Bob Cleek for he knows of what he speaks. I have just begun the interior treatment of a moulded ply runabout, (1957) that was a little punky in the bilge. The Smiths CPES does EXACTLY as he reported. Flows like water, grabs like hell, stabilizes questionable wood, and provides a terrific base for varnish, paint, primers, and STRUCTURAL epoxy formulations, (ie WEST System). A WORD OF CAUTION!!!! The solvents used as a vehicle to assist in the transport of the resin/hardener are EXTREMELY aggressive! Take it from someone who has sprayed more Nitrocellulose Lacquer, and catalized finishes than he can remember, WEAR A RESPIRATOR. I did a small test sample with the CPES on some end grain ply, and some solid stock 10cc's worth, just to see how the product handles. This is the worst cocktail of solvents that I have ever been briefly exposed to. After the 5 min test splooch, I immediately chucked two brand new cartridges in my respirator. Also, of course, wear gloves as with any epoxy work. With all that, positive fresh air supply is a nice idea, along with open doors. I can't stress this strongly enough. Great product, very useful for difficult problems, but protect yourself. Good luck with the stitch and "googe". Dave


Subject: Amen to the safety tip, Dave! Reply Posted by: Bob Cleek Date Posted: Sun Oct 4 12:51:49 1998 Message:

Yep, I forgot to mention what Dave added. I suppose all of us "epoxy heads" are somewhat calvaier about handling the stuff until we get "sensitized" and really have problems. (Knock on wood! which is fortunately always close at hand on a wooden boat!) I would mention that I ALWAYS try to use CPES outdoors and not in a closed space. When using it below, it has always been in small areas, and I exit quick with lots of ventillation. HOWEVER, if you were contemplating say doing your bilges or some large area enclosed below, I would go so far as to say, forget the respirator and go to a fresh air supply breathing system! Better safe than sorry... you actually can FEEL this stuff, not just smell it!

Messages In This Thread

Penetrating Epoxy
Brian C. -- 10/6/1998, 12:10 am
Re: Penetrating Epoxy
Patrick -- 10/8/1998, 4:25 pm
Re: Penetrating Epoxy, correct phone no.
R. N. Sabolevsky -- 10/7/1998, 12:45 pm
missing link
Brian C. -- 10/8/1998, 12:30 am
Re: missing link,
R. N. Sabolevsky -- 10/8/1998, 10:21 pm
Re: Penetrating Epoxy
Don Beale -- 10/6/1998, 12:49 pm
Re: Penetrating Epoxy
R. N. Sabolevsky -- 10/6/1998, 12:42 pm
Re: Penetrating Epoxy
Mark Kanzler -- 10/6/1998, 12:54 am
your answer
Brian C. -- 10/6/1998, 10:13 am
posted your question
Brian C. -- 10/5/1998, 6:33 pm