Best Ways of Applying Epoxy?

[Arne]

one advantage with epoxy is its slower cure time, giving better strength (it soaks furthe in the grain) and longer pot time to work with it.

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Polyester Material Info:
Polyester resins are the most commonly used matrix in the marine and composite industry. These resins are styrene-based, flammable and catalyzed when combined with Methyl Ethyl Ketone Peroxide(MEKP). When working with these resins in large projects it is advised to use gloves and a chemical respirator to protect yourself from the fumes. These resins can be used with any type of fiberglass, carbon fiber or kevlar, as well as used over urethane foam and other sandwich core materials.

These resins tend to be fairly rigid when cured and also more brittle than epoxy resins.
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[angib]

Melvin,

That's a brave man, tempting a re-start of the polyester .vs. epoxy 'war'.....

My attitude is that both have their place and both are very good in certain circumstances. However people do tend to favour one over the other rather like, I suspect, they favour one sports team over another - or PCs .vs. Macs, as one recent discussion went.

It's just like the difference between softwoods and hardwoods, with polyester being the softwood equivalent.

Andrew

[asianflava]

Much of the automotive fibreglass (EG: Corvettes and Fieros) is polyester with epoxy being used on boats

I think Fieros were plastic like Saturns are today.

[J.T.]

So far I've got most of the heavy work done but now I'm in a bind. Do I go with the epoxy and poly route? or do I go with the marine spar varnish route? I'm under lining the berch top with 1/4 in plywood and I need some input for a top coat, such as pros and cons.
I've never worked with epoxy before ecept for glueing small projects up. Any help for the experts would be apreciated as my wife is getting antsy for it to be finished.

[reo-ron]

OK guys here's my two cents worth. I sell Industrial Coatings and am a hot rod builder as well as teardrop novice. First epoxy resin based coatings come in more varities than most realize. There are coatings designed to mix with fiberglass mat/ chopped fibers etc for strength. We use this system to repair the bottom of in palce large oil storage tanks.It has pretty well replaced the polyester/vinyl ester systems. Then there are epoxies designed for applications in poorly prepared areas that will stick to and bind up impurities like moisture, tight rust, and slight oil contaminants. These are usually refered to as "surface tolerent" or "mastic" epoxies. Then there are epoxies that will cure underwater. And epoxies used as adhesives. Besides all of the above you also have the "Paint" type epoxies, almost none have UV protection. They do come in High build (6-8 mils ) and normal build (2-4 mil). They are also available in Gloss, semi-gloss and flat. Many are use for food service areas as well as potable water tanks and are NSF approved . Most of the "paint type " can be sprayed by a spray gun like the auto guys use. Most all can be sprayed with the addition of reducers(thinner). I used three coats of a 2-4 mil gloss in my galley and it is a nice slick finish, it is approved for food service (if anyone cares) and is easy to clean. Under my aluminum skin I applied a thinned coat of high build epoxy applied with a roller. It was thinned to allow for good penetration into the plywood and masonite. The second coat was an unthinned coat about 5 mils thick also applied with a roller. I was not real concerned with the appearance I just wanted protection against water under the Aluminum. This "treatment" also sealed the seams under the skin. If you want to save some money stay away from the Marine stores . Look in you phone book and find an Industrial Coatings distributor . Many carry the same products. For instance, I sell Urethane top coats for around $50-55 per gallon kit the same product sold thru our marine division is $70-90 per gallon kit. The yachat division repackages it and sells for over $100 . All the same stuff.
Urethanes. Come in a number of types. Moisture cured are the type that air dry without a "hardner" or catalyst. Often these are floor coatings finish coats. Aliphatic Polyurethanes require a catalyst and are somewhat flexible when cured and very chemical resistant. Usually UV protected. Acrylic Polyurethanes require a catalyst and are the basis for most Auto finishes. Also usually UV protected.
Now that we have this as clear as mud. I'll be happy to discuss this with anyone via PM.
PS. the garage floor stuff you see being sold in various places is usually an epoxy. and yes epoxies come as "waterboure" or "solvent based"
REO-Ron