VE Resin Promotion question

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#1

After promoting a fresh gallon of Derekane 411 VE resin I decided to mix up a couple of test batches just to be safe. Ambient temp was 90 degrees F. Batch #1 was 30g catalyzed with 1% MEPK. Batch #2 was 30g in weight and catalyzed with 1% MEPK CHP blend. Follows are the results:

  • Batch #1 gelled in 14 min but even after 1.5hrs the resin was still gummy - barely noticable exotherm.
  • Batch #2 gelled in 24 min but even after 1.5hrs the resin was still gummy - barely noticable exotherm.

I promoted via the suppliers specification for the 80-100 degree (F) ambient temps that the norm this time of year in Arizona. That is to say I used 3.6cc of cobalt ONLY and mixed thoroughly in a separate container.

My goal is to promote to provide the longest possible gel time BUT I dont want to sacrafice the final cure strength and I really dont want to wait a dat+ before I can sand the cured resin.

Question: Would adding a bit more cobalt fix the delayed final cure issue? I dont want to reduce the gel time but I’d really like the resin to get to a good and hard final cure within 1-1.5hrs at most.

Any advice appreciated!

James
Phoenix, AZ

#2

Anybody??? To Summarize the above post I’m simply looking for some advice on what I can change with the promotion of this resin to get it to final cure quicker but yet not reduced to gel time. Is this possible by adding more cobalt or possibly dma?

#3

UPDATE: Approximately 21 hours have passed since mixing the test batches and…

  • batch # 1 appears to have cured… mostly… the surface does not feel rock hard like I’d expect fully cured resin to feel but rather 95% hard with an ever so slight tackiness to it.

  • batch # 2 is still completely rubbery - I can press my finger at least an 1/8 inch down intothe 1/2 inch thick test batch.

I need some expert advice on how to re promote this resin with the goal of achieving the longest possible gel time but yet still attain a short & hard final cure. Ambient temp range this time of year is 70-75 (F) for the lows and 90-100 (F) for the highs.

#4

Would post curing it help complete the crosslinking perhaps?

#5

Are you trying to infuse?

#6

call the manufacturer and ask to get technical support. You will get the best information this way.

#7

Get another curing agent. I posted a table in another thread, where you can see geltime and time to peak. get something with a long geltime, but short time to peak.

And add enough cobalt.

#8

I’m at a loss… UPDATE: Thinking I may have had insufficient cobalt I added another .4 cc (4cc total now for the gallon of resin) and 1cc of DMA. I prepared identical test batches (30g catalyzed at 1% - batch #3 with MEPK and batch #4 with MEPK/CHP blend) and the only chanage was a reduction in gel time 11 min and 16 min respectively (see first post in this thread)… oh and my ambient was up to 93 degrees F for the test. The resin had VERY little exotherm and even after two hours still wasnt cured and I could easily push a tongue depressor (vertically) down through 1/2" deep resin in bottom of my mixing cups… (about the same force that would be required to push a tongue depressor into a frozen block of ice cream). I’m used to a farily warm/hot exotherm and then the resin is usually rock hard within an hour… with no post cure… In fact, I’ve never post cured anything I’ve built with this resin (the aircraft kit mfr doesnt call for post cure either) and I can usually sand this stuff within 1-2 hours (as in its rock hard… and dust comes off it when I sand it).

BTW: After 24hrs, the initial two test batches: Batch #1 seemed to be 90-95% cured but I could tell it still wasnt rock hard like I’m used to seeing with this resin… batch #2 was somewhat firm but still rubbery).

I’m at a complete loss here… I dont trust this resin (a brand new gallon that just showed up day before yesterday). The catalyst that I’m using is brand new from a local supplier here in Phx… The cobalt was brand new (came with the gallon of resin from the kit mfr).

Any ideas from you guys would be greatly appreciated!!!

HERMAN: Re your post… I would love to get my hands on some MEPK 925H but after several hours of calling around (in the USA) I cant find anyone that sells it. Any ideas?