Fiber glass-woodcore delam.

[wutato]

Hey guys, I have a big delam problem between the wood core and fiberglass, right after to the heel binding. This is a park skis with 180, 110/85/110, bamboo core super light in 3/12/3, one layer of 22oz triax fiberglass on each side of the core and another layer of the same triax for bindings. The think is that the fiberglass seems not stick well to the core and when we land bigairs with the weight in the back of the ski this delam making a wave perpendicular to the ski in the superior FG, no broken core, just bender to much and not broken the fiberglass, just delam like a wave. I think maybe we could make milimetrical holes to the core or a better sanding to give more texture so the epoxy stick better to the core, or maybe we are not using the best epoxy? Here in Chile we have to improvise with materials and suppliers.

[twizzstyle]

Sounds like an epoxy issue. The wood is slightly porous so you should have excellent bonding. Are you positive you had the ratios correct, and it was mixed sufficiently?

[wutato]

Hey twizzstyle, We are using a weight meter for the epoxy and a driller for mix. Maybe there is some specific characteristic that we have to use for the epoxy?

[MontuckyMadman]

sounds like the core is just not burley enough for you.
Could be resin poor matrix, could be poorly prepped bonding surface, dust or to hairy a surface of the wood.

[vinman]

horizontal or vertical bamboo?

I would think the horizontal bamboo could split under the force of park and pipe stuff.

[OAC]

How are you profiling the core? Router or planer? If planer, be sure to have sharp, very sharp blades. And sharp router bits for the router. Otherwise the wood fiber will not be 100% receptive. There is a document floating around in the forum describing that, do a search.
You can, as a pre step "paint" the core with an epoxy layer. Let it dry and sand it a little. This will ensure the bond a little better.

My 2p :-)

[amidnightproject]

If it's delaming like I think it is, it's a function of the strength properties of bamboo and the way it transfers energy to the rest of the materials.

[twizzstyle]

horizontal or vertical bamboo?

I would think the horizontal bamboo could split under the force of park and pipe stuff.

Good call. I made a pair using bamboo that had a middle layer of horizontal grain. I landed hard on the tails off a big drop and had a failure pretty similar to what this guy is describing. Mine wasn't really technically a "delam" as the layers didn't seperate, the bamboo actually failed.

[vinman]

Yeah Twizz I remembered reading that I think. Same reason I go with vertical grain in all my hardwoods. Same reason they place the labels for wooden bats on the horizontal grain. That way the ball technically is being hit with the grains oriented in the vertical plane of the wood. Stronger and less likely to split.

[MontuckyMadman]

Same reason they place the labels for wooden bats on the horizontal grain. That way the ball technically is being hit with the grains oriented in the vertical plane of the wood. Stronger and less likely to split.

never knew that. thanks

[wutato]

Thanks to all for the help, we are going to try some new things because we think that we have a new wood that seams to be like a "bamboo balsa" only from here in Chile, this let the skis quite lighter, like 20% left that a regular ski, and we want to make the ski as lightest possible. Maybe the paint layer of epoxy could help. Now we are going to invest in a press only for this bamboo, to get stiffer branches and mixed with the natural branch (lighter)

[dbabicwa]

Thanks to all for the help, we are going to try some new things because we think that we have a new wood that seams to be like a "bamboo balsa" only from here in Chile, this let the skis quite lighter, like 20% left that a regular ski, and we want to make the ski as lightest possible. Maybe the paint layer of epoxy could help. Now we are going to invest in a press only for this bamboo, to get stiffer branches and mixed with the natural branch (lighter)

Hey, is that similar to Paulownia wood? Fast growing?

I would seal bamboo with the epoxy sealer first...That is very thin (think water) epoxy and yes, you can paint it with a brush.

[wutato]

Yes, fast growing as 7 years. It is a "full-fill core" bamboo.
This Saturday we were looking at the broken ski and we take of the whole upper fiberglass effortlessly. It seems that the epoxy does not adhere to the wood core. Too much pressure? maybe this takes out full epoxy from the laminate. Perhaps the epoxy is not correct for this bamboo and didn't impregnated. We are going to make some testing about this.

[Brazen]

How do you like Chile? I noticed for awhile that the Chilean government was financing startups that would move there. Any idea how that went?

BTW, sand the cores with 80 grit, make sure you wet them out during layup. What pressure are you pressing at?

[wutato]

Hi Brazen, the startups here are good, we win one startup and we founded AWKA Skis this year. Many companies of iphone app and AWKA, one of the few outside of the computer technology. Startup was our best help to start our company.
We are pressing at 50psi and 50Cº. We already try sanding the core but doesn't make a big difference. Maybe the wood was not dry enough.