sealing ply

Use West.

Everybody else is copying them.

Not the best price point, but quality and consistency have a value beyond being cheap (less expensive).
Your boat deserves it.
IMHO

I'm not suggesting there aren't others that are worth while.
But why take a chance? There are enough problems with learning to apply any of them correctly.

 

I disagree, West's 105 formulation is fairly unrefined Bisphenol A. A couple of their hardeners show some refinement, but the basic slow and medium don't, which is what most people use. System Three has the same price point, with a little more refinement, but it's the discount formulators that are offering the best price point and refinement. This isn't to say you can't get better formulations from the big formulators, but is to say, you'll pay dearly for them comparatively.

RAKA, Progressive, US Composites and Bateau (E-Boat) are offering stable, reliable refined formulations that match and some exceed the big formulators physical qualities at far lower pricing (60% less isn't uncommon), so pick your poison.

All this said, both West System and System Three have lots of information about epoxy use, techniques and application variables, that it's certainly worth downloading their information packets.

In the end, it's usually not the epoxy brand that causes issues, it's the lack of experience and understanding of the applicator, so do yourself a favor and down the user guides from West, the Epoxy Book from System Three and the Gougeon brothers book on boat construction for an in depth look into the processes involved, before you smear goo on anything.

 

PAR,

What does "refinement" mean in your terms?

 

There are a number of things you can do to a formulation to improve attributes. Everything from emulsifiers, hardeners types, reactive and nonreactive modifiers, etc. 205 and 206 are about as basic as they get, with modest viscosity modification and little else. They blush if you just talk about moisture, cost two to three times as much as other brands and offer no additional physical or performance enhancements to justify these attributes. 207 and 209 do have more refinement, but they're still costly comparatively and have similar physical attributes of other formulators. Don't get me wrong, I cut my teeth on West, but have learned there are others, lower cost, same physical qualities and better features, such as non-blush, viscosity, discoloration, etc. I'm grateful of their industry testing and higher end products, but their bread and butter 105/205 line, is much less desirable than others that cost half as much.

 

not to mention UV resistance.

 

Most formulations don't have any or very little UV hinhobtors. The "clear" and "tabletop" mixtures are the exceptions. I'm currently testing a very different formulation from the usual A or F varieties, which does have a significant amount of UV inhibitors, with the idea it can be used without varnish over coats (I doubt it, but we'll see). It's a formaldehyde base with an over abundance of phenols, producing much lower molecular weight, while still being a thermoplastic.

 

Anatol - the advice that you got here from PAR and rwatson (and the others) is really very very very good advice.
My 2cents from another angle is, never try to save money on epoxy by buying less off it, we can only get the cheaper no-name brands in my country and they all work fine.
There is so much labour that goes into a boat and the peace of mind you get once on the water is invaluable.

Build well - and then go out and enjoy.
Epoxy painted, smeared, slapped onto plywood works very well and maintenance becomes very little
and a thin layer of glass fibre works wonders
I have crashed Fargo into the concrete so many times in storms, it does not matter anymore, and still no problem and still quick and easy to fix.
And all that is a layer of 600 gm glass and epoxy on the outside.

So bottom line is don't try to save costs by cutting epoxy

 

Manie
thanks for sage advice