On Tue, 14 Jun 2005 13:38:40 -0400, (DK TN) wrote:

What is the differences of these two "coatings//uses" ??? Is one better
than the other for:: IN water use---Above water-line use ?? As far as I
am "concerned"---BOTH are Petro--based--chemical= products??Thanks---

You will get a ton of different opinions, so I'll tell you upfront I
am biased toward epoxy resin for home boat building with plywood.
Others have different experiences, and I respect their views.

Here's my understanding of the three most common types of resin used
in amature boat building:

polyester resin: Has less "adhesive" properties, so some plywood boat
builders have delamination problems. It can blister if in constant
contact with water. On the positive side, you can use colored gelcoat
and not have to paint the boat. And its easily the least expensive
resin available. I find it harder to use than epoxy (but to be fair,
I have only used it once). It is used extensively in all-fiberglass
construction in production boats, but I think its the least forgiving
of amature plywood boat building.

vinylester resin: A modified form of resin that has better adhesive
qualities, and is more resistant to blistering. A very good choice,
I'm told, to use in place of polyester resin. Cost is a bit less than
epoxy.

epoxy resin: Very adhesive; epoxy is also used as a glue for gluing
wooden parts together, so many builders use it exclusively for all
gluing and coating tasks. Somewhat forgiving of fit and finish
issues, as it can fill voids and contributes great strength to the
repair. Cons are the cost, it must be protected from UV or it will
degrade, some people develop allergic reactions to it in its uncured
state, and mixing can be fussy ... there are 5:1 mixtures, 2:1 and 1:1
that I am familiar with. Get those ratios wrong and the resin will
never fully cure.

Others will chime in with differing views, and I'm sure someone will
find something in my post that they will nitpick ... so do some more
research on those three types of resins before making your final
decision.
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