degassing failure - no self collapse

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#1

i just got a 3 gallon aluminum degassing chamber from BestValueVacs so i could start degassing my epoxies.

i went to do my first degassing session, mixed up about 6 oz of some pretty thick epoxy, placed it into the chamber, and turned on the vacuum pump.

i’m using a Robinair 15600 6 CFM pump, so its decent and started pulling pretty quickly, it reached full vacuum in about 15 seconds. the bubbles started forming and raising just as expected within 45 seconds. but this is where the trouble starts, as it just hangs there:


no self collapse, even after 10 minutes.

so i shut it off and pulled out the epoxy and what i’m left with is an epoxy that has more bubbles in it now than when it went in:

even after letting this air off for 5-10 minutes, many bubbles still remain:

so i assumed perhaps the viscosity of the epoxy was too high, and it was just too thick to be properly gassed off quickly. so i tried again with a much thinner Pro Set laminating epoxy, and had the same results, with no self collapse:

what am i doing wrong? is the pump not strong enough? chamber too large or too small? something else?

#2

Some resin systems are just very tricky to degas. Heating up the resin helps (take it to maybe 80-85F, just put the cup in in a warm water bath) the most. I find that placing a scrap piece of infusion mesh in there can help agitate the bubbles enough to get them to pop, but this really just speeds up the process, it’s not a full fix. Heating it will be your best bet. I’ve used Rhino 1411 at 70F that didn’t degas worth crap, and then when I warmed it up a bit to a little over 80F it did fine.

#3

I do all my work indoors and climate controlled, so its currently 71F where I mix it and very well could be what the issue is. I just hope it doesn’t kill my pot life, as it’s already pretty short.

Thanks for the input, I’ll give it a shot and report back.

#4

Shake it during degasing. That will help. Another option is to go back to ambient pressure when the bubbles are big, wait e few minutes and degass again.

#5

Are you letting it at full vacuum the entire time, OR stopping it so it doesn’t overflow? If the latter, yes, it can take forever. I have ONE resin that will expand 10x the liquid volume. Another that only expands 2x. You have to let it go, or shake…

Now, if you let the vacuum pull (no leaks, right?) and let it pull the entire time with not touching anything, and it foams up, and never collapes and boils…then… Um…the gods are against you. Try degassing EACH part first, then mix. Also, as others have said, if warming helps, try that. Watch for exotherm and gel time of course.

#6

Multiple degassings suggested by the owner of Best Value Vacs, so will for sure be trying it tomorrow.

Full vacuum the entire time. For my tests I’m just mixing up a small amount, so its expanding quite a bit.

No leaks as far as I can tell, and its all full vacuum. It foams up to the top and then just hangs. Nothing. I emailed Best Value Vacs this exact story and the owner said he’d never heard of such a thing happening, but he’s been very helpful and I’m confident we can get it figured out.

Yea, the warming will more than likely fix it. I might have to switch to a different hardener, but if that does the trick, then I’ll be happy.

#7

What resin system are you using? Mainly for our collective future referencing so we don’t end up buying any of it and get stuck in your position :slight_smile:

For infusion, I’ve found that the Proset INF line degasses very well. I’ve had trouble with Momentive 86xx and Rhino 14xx series - they are both very finicky at anything below 80F. The Rhino system is good if you can get around that, very low VOCs.

#8

It’s a custom mix that I make myself with added UV inhibitors, so its pretty thick. It works very well for what we use it for though, so I’m hoping I can figure out a way to degas it as we have microbubble issues from time to time.

The Pro Set stuff I tried in the second round of pictures is a Pro Set LAM-135 medium viscosity laminating resin with the Pro Set LAM-226 medium hardener. I just got some samples of this and planned on trying some vacuum bagging with it, but haven’t yet as I only mixed it up to test the degasser.

I have a feeling its just not warm enough in my shop (currently 70F, with a low of 66F last night and these epoxies are just too thick at this temp. I’m going to run some tests today with everyone’s suggestions and will report back.

Which particular Pro Set infusion? I’ll ask my rep to see if I can get a sample.

#9

Okay, just got done with another test with a thinner epoxy and it degassed perfectly very quickly, under 2 minutes. Full collapse and only a few bubbles still in the epoxy when it was in the chamber, a minute or so out of the chamber and it was bubble free:


I double checked and there are no leaks in the system or the actual chamber, so I think its pretty clear that my original issues are just because the epoxy is too thick. I’ll try heating them up later today and seeing if that gets them to go.

Thanks for the input guys.

#10

Why not cycling the vacuum pressure?
Pull vacuum until it foams up, reduce vacuum until the bubbles collapse, increase vacuum again til foams up. After a few cycles you can pull and keep more vacuum til full vacuum.
I Have a resin were I do it that way and it seem to work fine and fast for me.
Thomas

#11

I’ve done both on pain in the butt resins, and normally it takes the same amount of time if you just let it rise to the top and hold it there, compared to collapsing the bubbles and doing it again. If it works for you, then great. Some resins just want to watch the world burn.

#12

The 114 line, I’ve used it with the 210 fast hardener and it degasses great. Good pricing too.

#13

also what helps is if you have the widest cup available so that they bubbles don’t have to float up too far through a viscous resin. wider surface area is easier imo then a narrow deep cup for the same amount of resin.

also aggitation during vac as mentioned