I was watching the west systems training DVD (came free with my epoxy purchase) and it mentioned that blisters form when water penetrates the gel coat and expands between gel coat and the epoxy. My question is, Is paint also suseptable to blisters???

yes, probably more so than gelcoat. You will get different results from different paints, but paints will blister, more like tiny bubbles. It some cases it will feel like non slip, usually will go away as quick as it showed up in non severe cases.

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Philip
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I'm trying to interpret your topic title...

"gel coat BS paint over epoxy and blisters"

the obvious

"gel coat Bull Sh** paint over epoxy and blisters"

doesn't seem to make sense?

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Damon Linkous
1992 Hobie 18
Memphis, TN

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Sorry that was suppossed to be VS or versus

PDS624

Sorry that was suppossed to be VS or versus

Well as Roseanne Roseannadanna would say..

Well, that's very different, nevermind!

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Damon Linkous
1992 Hobie 18
Memphis, TN

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do you really have to drill out the blister to repair it? as old as my boat is, I am guessing it is done drying\expanding so if I sand the blisters flush will that get it done or should I do as the west marine video says and drill a bunch of holes in my boat???

Now you got me confused. Where exactly are those blisters that are bothering you? In the gel coat, the laminate between the laminate and core or what?
Anymore of this and I'll have blisters on my brain....

I don't know how deep they are but I have a few blisters on the bows close to the water line. Unless I drillinto 1 I guess I have no way of knowing how deep they started or in what layer.

The question I have is can I just get away with sanding them off or are there other issues? seeing as my boat is an 87 I am guessing everything is as fully cured as it is going to get by now...

tap on the blisters and the surrounding area. a soft spot(de-lamination) will sound hollow noticeably. either way you will probably en up sanding off the blisters and "skimming" a pass or two of epoxy/sillica mix to fill voids and then touching up w/gelcoat. if de-lam, then injection trick along with sanding/fairing. this was a soft spot in my bow that was injected and skimmed and sanded to smooth for paint. this was a big soft spot before and after icoat of paint.

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bill harris
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prindle 16- "BLUE RIBBON"
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thanks for that! Luckly no apparant internal delam and NO soft spots so I think I am pretty lucky

Very lucky PDS...

if you paint over with 2 pack polyurethane instead of gel coat the stuff will blister if it gets wet for any length of time. I'd try using gel coat first. I believe its extra thickness makes it more robust. You will need some additives to get gel coat to harden outside a mold.
That said, be sure to store your cat off the ground (and not in tall wet grass either) if not on the beach or you will get blistering anyway.

Paul, just grind the suckers completely out and fill the hole with thickened gel.

forget about the blisters for a minute, with all the cracks in the gel coat especially on top, I am really not fond of it and the thought of putting more on the boat just doesn't give me a warm fuzzy if you know what I mean. I think I am going to grind it all down, fill it with epoxy then clear coat the whole boat with epoxy then paint it.