Ski Builders Forum

Hi,

we had some problems with a wood veneer and clear topsheet.
1. The wood seems to suck up a lot of resin. Should one seal it first with some coat before applying the epxoy?
2. We got a lot of airbubbles under the topsheet (there are also a lot more tiny airbubbles not visible on the photo). Could that be a result of the wood sucking up the epoxy an thus not being wet enough? Or is it more likely to have another cause?



Cheers,
Hannes

possibly not enough pressure at the spot to flatten the top sheet to the veneer.

1. Yes.

I had the same problem when I tried topsheet over veneer using Vacuum.
I haven't tried again, but one thing that was recommended was to add a "Luftraus" (Air out) No idea what it is called. It reduces air bubbles in your epoxy mixture.
You can get it from Georg at Skibaumarkt.de.

I like your name and logo! If you were going to do a lot of veneer boards, maybe you would want to press them flat with nylon topsheet first to make a veneer/nylon topsheet then mold later onto the boards.

Otherwise, why bother with a nylon top sheet for a snowboard, they don't get as many hits like skis do.

Georg at skibaumarkt.de also adviced us to use a lacquer first. It should prevent the epoxy from getting sucked up by the wood and yield a better bonding to the topsheet. I ll give an update when we have tried this.

@24Dave: Thanks! For the veneer only boards we won't use any topsheet anymore but we got some semi transparent graphics which only work with the wood underneath.

Think smooth.

The tiny air bubbles are because the surface is to rough and they can't escape.

Or don't use a topsheet. If vacuum pressing, the resin will impregnate the veneer fully - it's almost as tough as plastic. I use a piece of aluminum flashing cut the shape of the top sheet and waxed on the side that contacts the veneer as a release platen - no problems.

i use veneer with no top sheet and have had the same experience as kit.

The veneer usually gets impregnated with resin and is super tough. Sometimes there is extra thick resin on top of the veneer that I sand or scrape off.
Sometimes there will be dry spots on the top of the resin that look a lot like your photo of the bubble under your clear top sheet.

these spots are easily fixed with no top sheet with sanding and several coats of spar varnish or with a surface coat of clear resin that flows over the ski and off the edges.

I've found the boards with only veneer and then spar, hot coat, etc are not as durable as boards with a clear topsheet. They are fine for personal use but if you sell a board the buyer expects something as durable as any other bought board.
I've even tried some real hard coat, stuff that you can drive cars over, this stuff just ends up cracking if you give the board a hard time.

Entropy clear coat.

I have boards that are 5 years old now. And look fantastic still. I've had great luck with epoxy coats for durability. Better durability the top sheet in fact. if you smash an edge into it it just sort chips then is done. Smashing edges into top sheet you get tears then can potentially keep pulling.

what is the absolute thinnest clear top sheet that is available?
Is there any paper like product that would act like a very thin top sheet but also be able to have extra layers for a thicker top sheet in certain areas?

Just trying to curb the veneer.
I did a few small tests.
1 Varnished veneer with protective film;
2 Veneer with no varnish and protective film;
3 Veneer with extra epoxy on the top;
4 Veneer with just protective film.

I have used Henesport 150 spray coat for varnishing.

The best aesthetic result goes to the test number two, since veneer is covered with uniformly distributed layer of epoxy.
Seems veneer has good protection from moisture and scratches. But it has to be tested on torsion in order to determine weather epoxy cracks or not under the load.
The test number one also showed good result but I might haven't wait enough time for varnish to harden of did a wrong proportion of hardener to varnish, eventually in some places it was hard to unstick protective film.
The test number four shoved the worst result. The veneer was over saturated with epoxy and some of veneer stick to the aluminium.
The last test showed that using protective film over veneer almost avoid epoxy to comes out on the top like it was in the test two.


Never used any of other varnishes despite henesport 150 and it seems that they have to be hard enough to withstand action of finger nail.
I have seen some nice skis on the store with bamboo veneer on the top. The varnish seemed really durable.
The coat I am experimenting with seems nice but I can dig it with my nail.
The guys from henesport advised me this product as worthy protective coat.
I see that you guys use some different stuff to protect veneer but still, have anybody used this spray coat before?

Hello Motoman

I use veneer top sheets extensively and have had some good results.

I use a vacuum system, not press.

During layup I epoxy the veneer on both sides and lay it up normally. I then do one of two things

1. put a layer of silicone peel ply on top and vacuum - this produces a lightly textured surface which when cured and the epoxy has soaked right through the veneer. I then finish with several layers of special finishing epoxy

http://www.easycomposites.co.uk/#!/resi ... resin.html

2. rather than use peel ply, I put down a silicone sheet (known as a caul). This gives a very smooth finish and does not stick to the veneer, however it doesn't draw the epoxy through the veneer as well (because it is not permeable) so there may be some longer term issues.

Either way and with careful finishing I have been very happy with the finishes I have achieved.

If things do get scratched, knocking the finishing back, re coating and re polishing brings everything back to a nearly new finish.

Adding a layer of plastic adds weight also, as well as the bubbling issues.

Hope this helps

Gilo

Dear Gilo,
I have never used peel ply. As far as I know it suits good to be easy unsticked after cure.
I will do some experiments today with epoxy. I will make long and thin samples in order to check flexibility of the epoxy. Now it is main question for me))
Is it strong enough not to crack?

I don't know what caul means, I have not found any information in internet.
I tried to use R-TYPE AT 65L as protective film. Good result if you are going to apply varnish afterwards.

Best regards)