any thoughts on using a polyester based expanding foam in a wet epoxy layup in a closed mould ?
ive used an epoxy foaming agent before, but it doesnt have much ‘push’
I use that approach sometimes with urethane foam. It doesn’t need a lot of push to hold the CF in place if the layup is done correctly.
If I need extra pressure I would use the foam first to create a part-size plug and then force it into the part between the two halves of the carbon fiber shell by clamping the mold shut around it.
The foam plug may need sanding down a little to make it fit (depending on how many layers of CF you use but… as long as the foam plug is slightly oversized it will act like a rigid bladder.
Also, check your foam densities. They all expand at different rates.