Ski Builders Forum

My bet is on the inks! We've tried a few different UV inks with and without primers and none of them bonded sufficiently. I know it can be done though as J-Skis successfully use UV inks with a Fujifilm printer.

If you're pressing with heat, maybe it's because the metal of the edges and inserts gets hotter than the rest of the materials and that's what causes the ink bond to fail.

On another note: If you guys really want to do this professionally, you need to do a lot more reading on this forum (e.g. the cleaning with cleaning agents such as mineral spirits has been discussed on there multiple times) and set up proper tests for the materials you use! When trying materials (in your case UV inks) that are not regularly used on an industrial scale, you should build a testing rig for testing peel strength and make tests with small samples before trashing another entire snowboard.

Regarding mineral spirits, we had never problems with them. Just now we found out that they have harmful effect.
UV inks work good at least without heat blankets. We have already checked it when we did our very first snowboard. We have applied UV it to the topsheet. No delamination. Also we applied UV for topsheet under hot press. The same - no delamination.
We did 3 test for UV printing on the base.
1. UV printer which works under high temperatures (old models).
It was easy to split off inks with the help of nail. After hot press all inks were stamped on the fiberglass. It was really easy to tear off base.
2. We tried kind of expensive inks without primer. We were assured that we don't need primer in this case because it is last technological breakthrough in UV inks manufacturing. The result was much better but still we observed delamination.
3. Third experiment shoved us that good UV inks with primer have good bonding. But we couldn't explain the behavior under the press in the places of edge.

I don't know any tests to predict such situation besides like to make snowboard.
So don't think that we just do it without ulterior motives and see what will
happen.

I do agree with you that temperature of steel may cause it since it has high thermal conductivity.

Anyway all of those defective snowboards will be tested under high normal force, twisting and some other test to see ultimate strength conditions.
There are no waste of materials))))

Are you using heat?

Heat will make your epoxy thinner and it will run away/squeeze out.

My epoxy is very thin, and has to cure at room temp then get post cure heat or it will run out of the ski.
I only heat to 120-140f and my epoxy will run right out of the ski and all over the press!
Try your experiments without heat, I think this could be your issue.

Edited to ask;
Did you flame your sidewalls? This could be an issue.
But still think it's heat!


sam

sammer wrote:Are you using heat?


Edited to ask;
Did you flame your sidewalls? This could be an issue.
But still think it's heat!


sam

Yes, we use heat.
Also we flame our sidewalls and tip/tail spacer prior to layup.

We can't work without heat since we have non heated premise.
Unfortunately our epoxy is intended only for hot processes.

Definitely the epoxy becomes thinner under the heat, but there is no big waste after press.

Where do u put the thermocouple? I think its all getting hotter than you think. Its the metal parts that are not holding the resin.

MontuckyMadman wrote:Where do u put the thermocouple?

We put thermocouple in between aluminium sheets that cover heat blanket.
I think that temperature of cassettes at least the same.
But we want to buy independent thermometer and check exact temperature in between cassettes.

Chuck both thermocouples in a pot of water and bring it to boil. Water boils at 100'C so easy simple check and both should read exactly the same.

You did also mention you have no real resin waste after press, are you actually getting a decent amount of squeeze out?

How big are your press bladders? For example 60PSI with a 12" bladder is way too high.

Sammer didn't say press cold, you could simply try a test layup at say 45'. Or another way is to let it sit for 30 minutes at 30' so it can gel then bring on the heat. This will only add 30 minutes per build. Plus this is a really good way to get consistently flat bases. Epoxies don't need heat straight away to attain full strength.

gav wa wrote:Chuck both thermocouples in a pot of water and bring it to boil. Water boils at 100'C so easy simple check and both should read exactly the same.

You did also mention you have no real resin waste after press, are you actually getting a decent amount of squeeze out?

How big are your press bladders? For example 60PSI with a 12" bladder is way too high.

Sammer didn't say press cold, you could simply try a test layup at say 45'. Or another way is to let it sit for 30 minutes at 30' so it can gel then bring on the heat. This will only add 30 minutes per build. Plus this is a really good way to get consistently flat bases. Epoxies don't need heat straight away to attain full strength.

1. Actually we don't get too much waste of epoxy after press, but in some places like tip and tail the epoxy flows out and drops falls on the floor.

2. As for air bladders, they are approximately 8'' each in the diameter and 9'' in the flat position. We never exceeded 60 PSI. The reason is that under lower pressure cassette in the place of tip and tail curvature don't cuddle tight.

3. Do you mean that we have to put the cassette in the press that is already heated up to 30 or 45 degrees and keep it for 30 minutes and then heat up to out working temperature (80 degrees)?
I am afraid that epoxy won't cure. Manufacturer told us that we have to start at 50-60 degrees and instantly increase the temperature to 80 degrees. So the press has to be headed to 50-60 degrees before placing cassette inside.

Actually we have tried sublimation and the result was much better. But we have got next problem. The edge teeth and VDS rubber becomes visible.


I have red one post dedicated to this problem http://www.skibuilders.com/phpBB2/viewt ... 73f5be7342

Seems that there two ways: attach same layer of fabric or to backcoat base with something like epoxy consistent inks.

Way number 3: Use black base. No bonding problems due to ink, no VDS and teeth visible, easy to see if the base lacks wax, easy to repair.

pmg wrote:Way number 3: Use black base. No bonding problems due to ink, no VDS and teeth visible, easy to see if the base lacks wax, easy to repair.

Nice idea)) have already done it))

How can you tell that it's better if you can't see through the base? There still might be air pockets under that sublimated base.

It is definitely better then UV variant since I can't observe places of delamination. But you are right I can make final decision after I will grind the base. If so, sammer and gaw va might be right and reason may be in temperature and pressure.

Mate, looking at those original photos it really looks like you just don't have enough resin. How much resin do you use per board?

An 8 inch bladder should have little problem pushing the layup into the tip curves even at 30 psi. Have you got any photos of your press in action?

60psi with 9" contact width on your cat track and then spread to roughly 12" width of a board puts your pressure on your board as about 45 psi. I press with half that on the board.

Sounds like you might have more than one issue causing problems.