Page 1 of 1

Can you spar varnish over the staples in the outer skin?

PostPosted: Wed Jun 13, 2018 12:15 pm
by cfiiman
Hi everyone,

Long time reader, first time posting. I'll be posting an introduction thread with my build but wanted ask a question that I can't seem to find an answer to. On my outer skin I used 1/8" plywood with PL construction adhesive and 9/16" staples. I'm doing aluminum over the whole outer skin but wanted to go an extra step and spar varnish the entire outside plywood. My question is varnishing over the staples and will that waterproof them as well? Only other thing I know to do would be to take them out but there are hundreds and hundreds of them and would be a huge pain and I like the added holding power even though I"m sure it is not needed with the 8X PL adhesive I'm using as well. Never used spar varnish before so was just wondering if it is thick enough to cover the staples that sit flush on the surface of the outer skin, thanks for any guidance.

Re: Can you spar varnish over the staples in the outer skin?

PostPosted: Wed Jun 13, 2018 5:22 pm
by KTM_Guy
You could use wood filler or auto body filler like Bondo to fill the staple holes. Varnish it self is not going to fill the holes. I used three coats of epoxy rolled on before I put on the aluminum. It mostly filled the staple holes and will protect better than varnish.

Todd

Re: Can you spar varnish over the staples in the outer skin?

PostPosted: Wed Jun 13, 2018 5:46 pm
by Sparksalot
KTM_Guy wrote:You could use wood filler or auto body filler like Bondo to fill the staple holes. Varnish it self is not going to fill the holes. I used three coats of epoxy rolled on before I put on the aluminum. It mostly filled the staple holes and will protect better than varnish.

Todd


+1

I just wrapped up construction of a wooden kayak. The deck edge nails at the upper part of this image have fiberglass and 3 coats of epoxy over them to make them smooth. Varnish alone wouldn't do it.
154825

Re: Can you spar varnish over the staples in the outer skin?

PostPosted: Wed Jun 13, 2018 6:26 pm
by cfiiman
hi guys, thanks for the replies. But what if I leave the staples in? I'm assuming when you say fill the holes you are talking about removing them, but honestly there are hundreds, I was thinking of varnishing over the flush staples, thinking maybe that would seal them in?

Re: Can you spar varnish over the staples in the outer skin?

PostPosted: Wed Jun 13, 2018 8:36 pm
by Sparksalot
The varnish might seal them from a waterproofing perspective. It won't smooth them over enough to not cause possible grief with your skin.

Re: Can you spar varnish over the staples in the outer skin?

PostPosted: Wed Jun 13, 2018 8:38 pm
by tony.latham
What you don't want is steel staples next to aluminium. It could enable electrolysis and start corrosion. You could insulate the two by putting a piece of shipping tape over each staple if you don't want to pull them.

And...I think you're wasting good money by using spar varnish on wood covered with aluminum. (No UV issue.) Sealing the wood under the skin is a must as far as I'm concerned. I'd suggest a coat of slightly thinned oil-based polyurethane. Perhaps a second coat if it sucks too far in.

:thinking:

Image

Tony

Re: Can you spar varnish over the staples in the outer skin?

PostPosted: Wed Jun 13, 2018 10:01 pm
by KTM_Guy
cfiiman wrote:hi guys, thanks for the replies. But what if I leave the staples in? I'm assuming when you say fill the holes you are talking about removing them, but honestly there are hundreds, I was thinking of varnishing over the flush staples, thinking maybe that would seal them in?


I left them in, my air gun would counter sink them enough that they could be filled over with filler ( didn't fill them), the ones that were high would get a hit with a counter set punch.

Todd

Re: Can you spar varnish over the staples in the outer skin?

PostPosted: Thu Jun 14, 2018 8:50 am
by cfiiman
tony.latham wrote:What you don't want is steel staples next to aluminium. It could enable electrolysis and start corrosion. You could insulate the two by putting a piece of shipping tape over each staple if you don't want to pull them.

And...I think you're wasting good money by using spar varnish on wood covered with aluminum. (No UV issue.) Sealing the wood under the skin is a must as far as I'm concerned. I'd suggest a coat of slightly thinned oil-based polyurethane. Perhaps a second coat if it sucks too far in.

Tony


That is a great idea, I could cover them with aluminum tape. Also did you mean "sealing the wood under the skin isn't a must..." I read it and it sounds like that is what you meant but wasn't sure???


KTM_Guy wrote:
cfiiman wrote:hi guys, thanks for the replies. But what if I leave the staples in? I'm assuming when you say fill the holes you are talking about removing them, but honestly there are hundreds, I was thinking of varnishing over the flush staples, thinking maybe that would seal them in?


I left them in, my air gun would counter sink them enough that they could be filled over with filler ( didn't fill them), the ones that were high would get a hit with a counter set punch.

Todd


Yeah I had an electric stapler and the 9/16" staples were a bit much through hardwood poplar spars I guess. I hammered them down flush with a hammer the ones that were proud. In the end grain they countersunk fine. They are all now flush into the skin, not countersunk but not proud of the skin either so I don't think they will interfere with the aluminum on top.