Extremely slow infusion

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#1

I am trying to infuse a small plaster mold about one foot long, but it is taking upwards of 45 minutes to fully infuse. I was using MAS epoxy (800 cps) but have recently have switched to System3 SB-112, but I’m getting the same results.

I have been sealing the plaster with a few coats of clear acrylic, then 3 to 4 layers of paste wax. I am using 2 to 3 layers of 5.7oz 4HS carbon fiber, 1 layer of nylon peel ply and 1 layer of mesh flow media. A resin inlet is placed on one side of the mold and a vacuum line on the other side. The temperature is about 75 degrees.

Does anyone have any experience using plaster molds for infusion? The plaster always feels cold to the touch. Do you have to heat up the mold before using them?

Thanks

#2

All I have to say about that is your cps is WAAAAAAY too high!

I just ordered a 5 gallon test batch of resin specificaly for infusion to avoid those problems.

#3

You shouldn’t have to heat up the mold.

I’ve used the System 3 SB-112 before and although it wasn’t the best epoxy to use, it did infuse slow, but complete. I used it last fall/winter and found that heating it up with a small electric heater (slightly heating it- don’t go overboard or it will set way too fast) as the temperature in the shop was getting colder. Seemed to lower the viscosity a bit.

Another thing you may want to look for is the ever so tiny pin hole in the bag. This will cause the infusion of the resin to move at a snails pace.

Hope this helps.

#4

Also, a less than perfect vacuum (29"+) will cause a slower infusion. I would warm the mold and the resin. Warm resin in contact with a cold mold will increase the resin viscosity and slow the infusion.

#5

I agree - I have put a small cup of the SB in the micro to warm it slightly immediately before infusion. Not to much time though and not anything used for food prep.

#6

Try MGS 285 S from Aircraft Spruce. 250-300 CPS, with a 4 hour pot life. More than adequete for any VARTM.

Nick Anderson

#7

Problem solved. I heated up the plaster to 200 degrees in the oven, and warmed the resin with a heat lamp. The piece infused in less the one minute.

Thanks for all the replies
Sean