wood veneer onlay

What is the consensus on laying down a coat of epoxy before applying an onlay of 1/32" wood veneer? The whole design will be about 10 x 22 inches and be on the fore deck of a kayak. Any thoughts? SEEYA Jack


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RE: wood veneer onlay

Jack,

There's no point in doing that. I glue the veneers right on the deck using Elmer's white carpenter's glue and wipe off the excess with a damp cloth. Then I sand the edges as much as possible. The 'glass goes over that and several thin coats of epoxy with sanding between coats to even out the highs and lows. Several coats of varnish and you're done!

George

West River 18

RE: wood veneer onlay

Jack, I concur.  I just applied my first onlay, the clc compass rose, on my sanded, but un-epoxied Skerry bow seat and with three layers of epoxy completed, it looks fine.  I still have all that varnish to go as well.  Best,  Bob H

RE: wood veneer onlay

Does using carpenter's glue, rather than epoxy, reduce the strength of the boat significantly?  I'm not a boat designer and I have no idea one way or the other, just asking because the question popped into my head when I read this.

 

Specifically, could the deck fail under bending stress by delamination at the carpenter's glue layer?

 

As a layman I will take a wild stab at answering my own question, while I wait for an expert answer: no reduction in strength because the epoxy/'Glas skin is so stiff, and is out at the skin where strains are greatest,  that it would prevent the carpenter's glue layer from ever getting near its yield strain?

 

RE: wood veneer onlay

Camper,

I don't think the glue joint will ever fail for a couple of reasons. First, have you ever tried to get a joint to fail glued up with the stuff? Pretty difficult. Then try to get the veneer off a flat, or slightly curved surface as a kayak deck, after the glue has set. Better get out the sander! Second, there's not significant flexing of the deck to cause a veneer bond failure as the veneer is more flexible than the okoume anyway. Third, the cloth/epoxy over the veneer insures it ain't going anywhere. My West River is over four years old and has been from Florida to Maryland (several times) and to Texas (twice) and a few states in between. Been in the ocean, on rivers, lakes, on top of the car in the Florida heat and sun and in bitter cold on the Chesapeake. No signs of any delamination. In fact the Epiphanes varnish still looks pretty good although I really should do a light sanding and another coat someday. But who has time for that when there are so many more boats to build?

George

RE: wood veneer onlay

Thanks guys I'll go at it w/o . SEEYA Jack

RE: wood veneer onlay

Thanks, George.  No, I've not done any testing to failure on either kind of glued deck, so I have no info.  But my hunch is the same as yours.  If anybody did test to failure a boat with a carpenter's glue layer and one without, there would be no significant difference in strength.  Of course, only a test to failure of both construction methods would give any info on the question.

 

RE: wood veneer onlay

Guys,

In either case the wood would fail before the glue. Epoxy's advantages are that it's gap filling and waterproof. Neither is necessary for decks which are epoxied and glassed after the onlay is put on.

Laszlo 

RE: wood veneer onlay

Laszlo, thx for the expert answer. 

 

You got me thinking.   From what you say, does it follow that we could glue the fiberglass onto plywood with carpenter's glue, and then apply epoxy to the glass, with no loss of strength (since the wood fails before the glue) ? In some cases, that would be more convenient because there would be no time constraint after the glass was glued down.

RE: wood veneer onlay

Camper, you're dangerous :-)

Not unless the glass/glue bond is as strong as the wood/glue bond (not to mention the epoxy/glue bond). I was speaking very specifically about a thin layer of carpenter's glue betyween 2 pieces of wood.

There's also the issue of the epoxy matrix for the glass. Unless the wood glue can match those characteristics, too, the glass/glue composite won't work the same as the glass/epoxy composite.

Laszlo

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