i have a board that had several huge delams that i cut out, and now i have a couple deep empty chunks of foam missing. is cabosil the best modifier to use with resin or should i look at some other fillers? the dings are pretty vacuous, so i want to make sure i can keep the board as light as possible after the repair. this site has some great products http://www.fiberglasssupply.com/Product_Catalog/Fillers/fillers.html if anyone can recommend me something that could best address this repair job, it would be much appreciated (the hollow microspheres looks useful).
On the delams I have done well, I have used either microspheres or an inlay of scrap foam depending on the depth. To replace volume you are looking for low density not strength.
It’s only feasible to use sheet or scrap foam if you have an even surface to bond it to (i.e. routered out holes). If you don’t have a routered out cavity, you can use a urethane product called “pour foam” from US Composites in FL. Get the 2 lb density, mix it and pour a layer in the cavity. Sand, surform, or plane it down after it foams up. Fill the pores in the foam with a lam resin/cabosil mix before laminating.