Expoy Sanding

I am building my first boat (CLC Ultralight Dinghy).  The build notes instruct you to coat the transomes with two coats of epoxy (no fiberglass on these parts) then sand to 220 grit for finishing.  I have done a LOT of varnishing over the years.  I assume the point of the epoxy is to seal the wood, but by the time I finish sanding to the point that I would be ready to varnish I feel like I sanded off all the varnish.   Is that an optical illusion or did I waste my time?

 

 

 


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RE: Expoy Sanding

"...but by the time I finish sanding to the point that I would be ready to varnish I feel like I sanded off all the varnish."

Did you mean instead to say EPOXY where you used the second word varnish perhaps?

The goal here is twofold: protect the wood (by means of sufficient coats of epoxy to prevent water from getting to it) then protect the epoxy (which by itself isn't sufficiently resistant to the effects of UV radiation out under the Sun) by means of UV-inhibiting varnish.

If the two epoxy coats you've applied to your transom have been sanded enough that wood grain is exposed, then you need to apply more epoxy.

The goal is to leave a thin film of it to protect the wood underneath. Enough to form a tough, protectve membrane but not so much that the weight of epoxy becomes burdensome.

Adding UV-protective varnish as an overcoat ensures the epoxy won't degrade prematurely during use. But that varnish may need renewing every so often, just as in traditional wooden watercraft maintenance practices.

220 is fine enough to knock the epoxy's high spots down but if you sand too much off you're defeating the purpose of the epoxy coating to protect the wood underneath. It needs to be 100% intact so there's no wood left exposed when you start your varnishing.

RE: Expoy Sanding

Yes, you are correct I meant to write epoxy.  So my problem probably is that I don't have much experience working with epoxy.  My application had a lot of fisheyes that required me to be pretty agressive with the sander.  

It would seem to me that the most important part to seal is the end grain.  I am confident enough in my vanishing skills to know that I can encapsulate the wood with varnish.

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