[Public-List] bottom paint/thin gelcoat

[Rachel]

On Aug 8, 2008, at 11:57 AM, Rod Symmes wrote:

> My understanding is that the gelcoat is waterproof  -  and 
> epoxy/fibreglass is not very.

Actually, it's the opposite.  The gelcoat on our boats is polyester, 
and is rather permeable (that's how the water gets in to make blisters 
- it goes through the gelcoat).

Epoxy is the main ingredient in barrier coat, along with additional 
solids they add (either to "normal" epoxy such as WEST System with 
their additive, or pre-done in something like Interprotect 2000, which 
is epoxy based).

Now if you don't have a blister problem, you don't necessarily need to 
add epoxy/barrier coat; but neither do you need to replace gelcoat in 
order to make the boat "waterproof."

>  I would be inclined to either fix the gelcoat or put on several coats 
> of a barrier coat.

I would still say that repairing the gelcoat is only if you want a 
cosmetic fix (which makes sense if, say, you dry sail the boat and it 
has no bottom paint).

  I won't drone on about blisters and such, but here's a link to an 
article if anyone does want to read more.

http://www.zahnisers.com/blisters_hydrolysis.htm

Rachel
#221


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