Glassing The Inside Hull

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Mark Prendergast
Posts: 4
Joined: Wed Dec 02, 2009 3:39 am
Location: Ashburton, South Island, New Zealand

Glassing The Inside Hull

Post by Mark Prendergast »

I am ready to glass the inside of the hull of my first build, a Freedom 17. I need some clarification on the timings between the first and second coats of epoxy. "Canoecraft" advises that after the first coat has sufficiently firmed it should be lightly hand sanded with 120 grit sand paper. Can someone please indicate to me how many hours that is likely to be after the first coat was applied. I am in New Zealand, it is spring time and our temperature is currently around 18 to 20 degrees Celsius.

I imagine the goal for sheathing the inside is the same as sheathing the outside - to obtain a chemical bond between successive coats of epoxy. Under our current climatic conditions I expect to be able to apply the second coat of epoxy after about 4 to 5 hours. What I need assistance with please is, when do I hand sand the first coat? If I wait long enough to hand sand the first coat is a chemical bond possible with the second coat of epoxy? Is it possible to hand sand the green epoxy then apply the second coat on the same day?

Thanks
Mark P
willo
Posts: 156
Joined: Sun Jul 15, 2007 12:48 pm
Location: Echo Bay ON.

Re: Glassing The Inside Hull

Post by willo »

The second coat is a filler coat and depending on your epoxy can be done as soon as the first coat gets past the tackky stage. I have never sanded between them. Many builders do not even apply the second coat , opting for a rougher surface. Under normal conditions the second coat can usually be applied a few hours after the first. you want to make sure there is no signs of bubbles or gassing from the first coat since ading more epoxy will make it worse.
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Patricks Dad
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Joined: Wed Oct 13, 2004 1:11 pm
Location: Warrenville, Illinois

Re: Glassing The Inside Hull

Post by Patricks Dad »

Agree with Willo... If you put the 2nd coat on soon enough, you will achieve a chemical bond and will not need to sand. I have never sanded between coats of epoxy. If you wait too long you will need to sand to introduce a mechanical bond (but will have the headaches of worrying about sanding into the glass as well as the clean-up needed before applying the 2nd coat). The timing (the focus of your question) is a function of the type/brand of epoxy you are using (which I don't see in your post) and the temp (which you do note).

Ah, spring... We're headed just the opposite direction here in the north. Enjoy your spring, your build and your paddling!
Randy Pfeifer
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Randy.Pfeifer1@gmail.com
Mark Prendergast
Posts: 4
Joined: Wed Dec 02, 2009 3:39 am
Location: Ashburton, South Island, New Zealand

Re: Glassing The Inside Hull

Post by Mark Prendergast »

Great stuff, thanks fellas. That was just the comfirmation I was searching for.

Randy, I am using the West System as recommended in Canoecraft and I find it good to work with given my lack of experience in this field.

The two coats of epoxy will go on today. Forecast is for warm weather 18 -20 degrees C, humidity is 45%. My camoe will ready in a few more weeks ready for the best of the fishing season.

Thanks again guys.

Mark P
Rod Tait

Re: Glassing The Inside Hull

Post by Rod Tait »

I think the sanding may be in reference to adding extra pieces inside in the ends where the full piece is hard to make fit. If there is overlap, then you wait until hardened, sand rough edges and then apply another coat.
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