What's Causing These Bubbles/Pin Holes?

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#1

Hey guys,
I’m having a little trouble with the infusion still. I took my time to do this infusion. Since all I could get in a pinch for vacuum bagging was the stretchlon 200, I put an extra layer of the stretchlon in top of the mold. Enveloped the whole thing and did a 1 hour drop test with no loss in pressure. I degassed the infusion epoxy for a good 20 minutes followed by letting it sit for another 10 min to let any small bubbles at the top pop. Infusion in the part went well, I slowed down the infusion through the mesh since it went fast. After the epoxy passed the part, I clamped the resin feed followed by the resin outlet. It looked perfect with no bubbles but after about 20 min, I came back to check on it and noticed air bubbles in the mesh which I assumed was normal. After 2 days, I opened it up to find bubbles in the epoxy (see pic at the top) and pin holes only in the section in the pic.

I was thinking maybe I had a very small leak, but the bag didn’t lose pressure. You guys think its time that I try the MTI hose? Or is there something I missed?

#2

Put this bag in a trash… most stretchlon bags are poor materials , when i tested this many times get leaks not when laminate was dry but only few minutes after infusion ended…

steps:
slow down infusion,
dont use spiral tubing at such little thing ,
swap the order of clamping hoses

come back with results

#3

If you can see any ‘bubbles’ through the bag, immediately after infusion, then the bag isn’t sealed correctly. Also, yes, switch the order of clamping. Clamp the vacuum draw first, and then clamp the resin feed. This will help reduce pressure within the bag, minimizing the effect of pinholes.

#4

When you say don’t use spiral, do you mean just run the hose directly on the flow media?

#5

On a part so small spiral tubing isnt necessary. Over kill in my opinion.

Don’t use stretchlon. Flowmedia will puncture through the stretchlon. IF, you have to use stretchlon use the pink one. I believe it stretchlon 800.

The green econo bag from airtech (120" wide) is the best. Its the best in price, and works amazingly well for pretty much all applications. Not sure about elevated heat temps, but it works great for room temp cures.

#6

Exactly mean that , and spiral tube is good for parts starting from at least 50cmx50cm , so dont worry , and rushing resin across part is also major cause of pinholes like you have.