I have made a couple of custom parts for race cars, along with the molds to duplicate the parts. I have noticed the use of 3m 77 spray to help keep the carbon in the tight spots while vacuum bagging. My first part is shown below it was vacuum bagged only. I have made a smaller part for a subaru wrx using infusion. The part also requires the 3m 77 to keep the carbon in place. My issue comes when I demold the part its never a perfect shinny surface, it usually requires addional coats of resin than wet sanding and clearcoating. I would like to demold than clear. I am currently using a polyester based resisn from composite envisions. What kind of resin should I be using for vacuum infusion. I know I just rambled off a bit of info but I would love any help you can give.
Real easy way is to brush or spray gel coat in the mold and let It tack up. Then lay your first layer. brush in resin another layer and vacuum down.
Unfortunately there is a bit of work involved. The smoother the mold surface and release is the better the finish is.
FYI for pre pregs there are face coats of nothing but a ply of adhesive that buffers the surface to help with pin holes and print through.
You could try spraying a gel coat and letting it cure… Then infusing over that. West systems has a clear polyester gel coat that’s real easy to work with.
For infusion i Use a polyurethan in mould coat, it can also be used by all other processes. Have you tried another spray adhesive? The 3m 77 is not bad but often causes problems because it is visible. But most important is not to use too much adhesive!
For infusion i would only use special infusion epoxy resins. Most other resins work, but not perfect.
If you want a shiny surface after demoulding your mould has to be perfect.
I think west systems make the best epoxy and the metering pumps are very convenient. Apply a brush coat and wet sand 200 to 1200 and then buff. I’ve also used a syringe and needle to release the bubble top and they inject the larger bubbles.
I’m relatively new but I get help from calling west system tech line and they are always ready to help.
If your process parameters are fine there will be no bubbles:)
are there better resins to use for infusion, and what do most people use to get the carbon to stay in the contours of the mold
To answer your question we use vacuum bags, caul plates, 77 spray, gel coat and bladders. Any one or any combination of these items and or methods combined or separated can hold the laminate in tight corners.
Can u recommend a clear gel coat, I sometimes use a light coating of the infusion resin to tack up the mold but it dosent always work as well as the spray 3m
There are a lot of clear coats you can use, I prefer a polyurethan clear coat. To hold the fibre down you can use different spray adhesives. A good one for example is the airtack from airtech. Using epoxy may cause problems with the second layer of epoxy. There might be no compound.