Question for my Resin people

I had a fellow ask if it would be possible to use our vacuum pumps (but not, I think, the resin set-up) to make some carbon fiber things. I gathered that he will be buying some special items to put the carbon fiber in.

@Lordrook @Hanna_Kessler and others – what say you? Will this cause issues with any of our processes?

Umm, I’m not sure what the process is or what exactly he’s trying to accomplish. My main concern is anything getting into the vacuum pump, since any dust or particles may be sucked up into it.

A vacuum is pretty common when doing any kind of composite work. Usually there’s a catch pot between the work and pump to make sure no resin flows into the pump. If they’re talking about wet layup or infusion there’s no dust generated.


I don’t see an issue then as long as he uses a proper container to avoid mess in the pot.

If he is just using the vacuum pump I would assume he is bagging it “wet” , so no fibers or dust, a small catch jar between the bag and pump should protect the pump for any drips that get sucked out of bag.

I learned on youtube that the optimal vacuum bag pressure for doing carbon fiber wet layups is 20% (I’m guessing 20% of a total possible of 100%). It was suggested that the vacuum bags you can get for storing clothing and stuff for use with common household vacuum cleaners produce the ideal pressure.

So that’s what I’ll be using.

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When they were bagging carbon fiber parts for aerospace it seemed like they were going until they had had good squeeze out and saturation of fibers and no air bubble visible. Then it went into autoclave (10’ dia x very long). Not sure of pressure, but they squeezed it a bit more to ensure layers in bag were tight against mold/tooling.

@Chetan_Raj could give you advice on infused wet carbon layups.

When I was doing hand wetting I always wanted the maximum amount of pressure possible on the vacuum layup so that the layers were as close together as possible; the epoxy is the weakest part of the bond.

I’ve seen carbon fiber done with peel ply and then a layer of absorbent material. So the atmospheric pressure is being used to squeeze as much excess resin as possible out of the fiber, through the peel ply, and into the absorbent waste matting. The extra resin is just extra weight and thickness with little to no positive benefit.

For those interested, the youtube channel I mentioned above is called:

Easy Composites Ltd

Interesting stuff, and they have all the supplies as well.