Epoxy problems


 Can anyone help? I´m building my ches 17 in a cold european climate. My garage has a simple gas heater which takes the edge off the cold but its still not ideal.

The problem is my deck which has been treated with epoxy. Having left it for a couple of weeks I decided the sand it with a fine 240 paper. When sanding I notice waxy build ups and smears across the surface, rather like a cloudy smudge. A kind of epoxy crust.

My fears are that its still not completely dry although it feels it to the touch.

Is this the case and can I sand these unsightly blemishes away?

I dont want to make it any worse than it is. I have not sanded through to the cloth either so its not that.

Any ideas ?? Thanks


6 replies:

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RE: Epoxy problems

I had the same problem (also on a C17), and it seems it's the epoxy clogging up the sandpaper to the point that it smudges the surface.  Best thing to do (in my experience) is change the sand paper often... seems like you have to change it every few feet of surface sanding, but that's what it takes.  You might try sanding those "smudges" out by hand, maybe using a heavier paper (like 100 grit). 

And my epoxy has cured for months, so it isn't related to curing, it's the nature of the epoxy.

Hopefully someone with more experience (Laszlo???) will weigh in here.

Good luck, it's a great boat!


RE: Epoxy problems


Thanks Larry. You might be right. Another thought just struck me. Think I have been sanding at a too high speed. Just tried at a low-moderate speed and it seemed to to help. I think also you are right when you say hand sand the clogged parts.

Dont think it pays to be hasty...

Thanks again for advice.

RE: Epoxy problems

The epoxy ought to be dusty when you sand it, no exceptions.  If not, something is wrong.  Apply heat.

Mixing problems come up, but this time of year it's usually got to do with temperature.  Epoxy doesn't cure in the cold;  it needs room temperature or better.  That means 60 degrees F or 16 degrees C, or better.  And that's not just the air in the shop---that's your boat, too.I get a lot of uncured epoxy calls from builders who flicked the heat on in their shop, but set to work on a hull that was still ice cold.

I'm also uncomfortable with the idea of just waiting patiently for cures in cold weather.  All the evidence I've observed, plus what the chemists tell me, is that epoxy applied to cold surfaces or in cold rooms doesn't cure to the same strength.

Read more on epoxy and cold weather.  It doesn't need to be difficult or expensive to warm up your workspace.  


RE: Epoxy problems

Could it be "amine blush"? Try washing it with warm water and a sponge, then rinse and wipe it dry.

CLC Epoxy Tips and FAQ

RE: Epoxy problems

I had a problem similar to this as well.  After talking to other experienced boat builders, it was recommended that between every coat, I wash the surface down with some soap and water.  As you mentioned, a waxy finish is the byproduct to opoxy.  I used a sponge, dish soap, and the garden hose.  This seamed to solve all my problems.  It also eliminated the need to sand between opoxy coats.

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