What's the best option for filling tiny holes in cast?

I made a mold from a foam latex mask with the aim of fixing all the damage then remolding. The big air bubbles are not a problem but there are thousands of tiny holes from the pores in the foam. I could use bondo filler but there are also a lot of lines on the mask that I don't want to fill, and am worried that a lot of sanding is going to lose some detail. Is there anything else I can use instead? I was thinking of a very soft clay that I could brush on then wipe off leaving the pin holes filled.

You could use spot/knifing putty.

Thinned out bondo spot putty with lacquer thinner.
Liquitex Gel media.
CA glue (add baking soda to larger holes)
Magic Sculpt or Aves epoxy putty.

andy19422 said:

I was thinking of a very soft clay that I could brush on then wipe off leaving the pin holes filled.

Click to expand...

I do this often and depending on the type of surface, it works quite well. I usually use a harder type of clay and just smear it in with a finger. If it is too soft, you will fill in the holes but there will still be an orange peel look to it. You probably won't be able to do this everywhere, but this should quickly fix a lot of the area. Be careful that you don't get it in places that you cannot clean. Just be aware that you will likely not be able to get it back off of the original so if you don't want to, or cant destroy the original, make a copy of it first and repair the copy.

Another thing... make sure your clay does not have sulfur in it... some silicons to do not like clays with sulfur and they will remain tacky in the area of the clay.

Thanks Opal, I have just tried fine finish plaster filler and it works great. I have also turned the mask mold inside out and cutting off all the air bubbles from the silicon and carefully scraping the silicone with a scalpel to remove most of the silicone beads that make the holes in the resin. This will mean a lot less filling

Upol dolphin glazing putty. Like runny bondo

Thanks, I've just ordered some to try. Looks great on youtube