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Well, it works to a point, but ultimately is a fail.

The paper backed veneer looks perfect and bonded well to the ski... the 8210 is bubble free and bonded well to the top of the veneer. Where it fails is that the 8210 is only bonded to the outter most, thinnest skin on the veneer. I think this is because the veneer isn't soaked through with epoxy and you end up with a 'dry' veneer core, between the paper backing and the outter visual portion of the veneer. When I pick a corner of the 8210, it breaks away from the veneer and I can peel off the entire 8210 from the veneer... there is a thin skin of veneer still attached to the 8210, but the rest of the veneer remains adhered to the ski...

Veneer bonded to ski... veneer bonded to 8210... veneer not bonded to veneer anymore.

Thoughts anyone? Any ideas on how to soak the veneer to the core during layup so that it maintains it's integrity?

https://docs.google.com/file/d/0B5F6ikv ... FzcjA/edit

astroskidder wrote:The first step went well. No problem seeing the bubbles and working them to the edge of the 8210 with the squeegy. The assembled veneer and 8210 has cured and can be formed to any shape, but is quite more stiff than either product on it's own.

Next step is the actual mock-layup... more later.

astroskidder wrote:I am running a test that I will post an update on once I get some results...

Using 8210 and laminating it to a paper backed wood veneer as a first step, basically creating a wood veneer prepreg to use in the layup process. Buttered the top side of the veneer and the bottom side of the 8210 and used a 6 inch epoxy squeegy/spreader to push the air bubbles out towards the side... once I was happy with the look, I set it aside to cure.

My plan is to then use the above as the final topsheet during my layup. The paper backed veneer will be buttered and laid down over the final layer of glass and then the ski pressed as usual.

Don't see any reason why this should't work, but I've been wrong many times before.

Hey astro. Dont peel the topsheet. It works fine. This will be the same no matter what you do. Peel strength is not a good measure of this type of bond.

Not too sure what you mean MM...

How does it 'work fine' if the top sheet peels away from the veneer... seems to be a pretty good measure of bond if the 8210 can easily be pulled off the substrate.

Cross tips and get a chip or lift in the 8210 and any curious monkey is going to pick at it regardless of having opposable thumbs... next thing you know you're pulling away hunks of topsheet. Monkey see, monkey peel.

MontuckyMadman wrote:Hey astro. Dont peel the topsheet. It works fine. This will be the same no matter what you do. Peel strength is not a good measure of this type of bond.

I have to agree with montucky
It looks like the bond was fairly good.
If you try to peel anything hard enough it's gonna come apart.
Top sheet is peeling the veneer so that's the weak link.
What do you expect? If you can get epoxy thru your veneer then it may be the same.
Looks to me the veneer failed not the bond?

sam

'Fairly good' bonds don't cut it. Honestly didn't try to pick/peel it that hard... once a bit of it has lifted - as it would in a tip/tail cross hit situation - the rest peels back quite easily.

I suppose I expect a discussion as to some solutions to the problem. I agree with you that the veneer is the weak link, but I think that's what this thread is about... trying to find a way to adequately bond 8210 to wood veneers without bubbles and general adhesion failures.

I wonder if a random strand veil between the veneer and the 8210 would help with a more resin-rich bond?

sammer wrote:I have to agree with montucky
It looks like the bond was fairly good.
If you try to peel anything hard enough it's gonna come apart.
Top sheet is peeling the veneer so that's the weak link.
What do you expect? If you can get epoxy thru your veneer then it may be the same.
Looks to me the veneer failed not the bond?

sam

Sammer might have brought up a decent point. Looking at the pictures I would say the veneer failed. What type of veneer did you use (how permeable was it). Did pour epoxy on both sides and give it a chance to soak in? It appears you used a clear topsheet. Also, how thick is the veneer?

Western Cedar veneer with a paper backing. The paper is 10mil (0.01 inch) and the veneer is about the same (0.01 inch) for a total of 0.50mm.

I was also thinking about the amount of time given to let the epoxy soak in... I'm going to try using a mix with a longer pot life so I can let is soak longer and will update my original post with some new findings tomorrow.

Thanks for all the input everyone... cheers!

Jekul wrote:Sammer might have brought up a decent point. Looking at the pictures I would say the veneer failed. What type of veneer did you use (how permeable was it). Did pour epoxy on both sides and give it a chance to soak in? It appears you used a clear topsheet. Also, how thick is the veneer?

astroskidder wrote: I wonder if a random strand veil between the veneer and the 8210 would help with a more resin-rich bond?

If the failure is in the veneer, what will additional fiberglass do?

My only idea is maybe heat it up a lot more to try and help the resin really soak into the veneer. Or use a less viscous resin for just this step.

astroskidder wrote:Western Cedar veneer with a paper backing. The paper is 10mil (0.01 inch) and the veneer is about the same (0.01 inch) for a total of 0.50mm.

maybe you should check your maths again

using thinner veneer and a resin with a longer pot life and lower viscosity should help with soaking the veneer.

Some veneers bond well, some not so. Traditional cedar doesn't bond very well. How well it appears to saturate the veneer is a good finger in the air measure.

Have you separately assess the effect of the paper backing - what adhesive has been used to attached the paper. Will it formed a barrier between the various layers and void any result?

Western red cedar in super easy to split, it's own internal bond is weak.
That's why they make shakes and shingles out of it.
It's fairly weather resistant but weak along it's grain.
Try the same experiment using something else.
As I said earlier the bond to your topsheet looks good but the wood split along it's grain.
Try it with a maple or cherry veneer, I bet it works way better.
Also I would avoid paper backed veneers. I know some people have had luck with them, but, a full width layer of paper sounds like an invitation to disaster.
It's just adding another unknown bonded layer into the mix.

Just my $0.02,YMMV, yadda yadda yadda.

sam

I agree with Sam on this. I did use some paper backed birch this year without any issues yet... But it is heavier and I wonder about it wicking water in to the laminate.