I am working on my first foam patterns for a plaque. I'm still getting used to the hot wire and cutting contours. So, I have a couple of spots that won't sand out and I want to fill. I think I have read in the past to use wax. Question is, is there a certain type of wax to use? I'm pretty surprised how well this pink foam sands out. A little time with some 220 did wonders. Thanks, Ed
How big and deep are the spots? I don't think there is anything magical about it but low melting point is somewhat important so you don't damage the foam with heat. Low ash on burn out is also a factor but I think most waxes will be fine. The toilet ring seals are very low melt point, inexpensive, and available at big box/home stores but you might get by with crayon or even candle wax. Canning Paraffin is also a candidate. Experiment on a scrap piece of foam. A piece of flat or shaped sheet metal or maybe a butter knife or small spoon heated by a hair drier, heat gun, or lean flame can serve a tool to trowel. I use pattern makers fillet tools and pattern makers fillet wax because I had them. Best, Kelly
Thanks Kelly. After you said toilet ring, I remembered reading that before. As far as the depth ... I guess most are probably less than .020", one or two small spots might hit .030". If it wasn't intended to be a plaque, the spots wouldn't be an issue. They are on the sides of raised figures, so will be hard to get rid of later. I'll pick up a toilet ring tomorrow and see if I can't remember where my little alcohol burner is stashed. Thanks, Ed
Filling modest sized blemishes like that should be know problem, but just a matter of being able to work the semi-solid wax to the finish you want. Complete all your sanding in the vicinity of the patch before you wax as it will load sand paper and not work the same as the surrounding foam after you apply wax. Best, Kelly
Sometimes a little piece of scotch tape works well to cover slightly bigger holes and pits in the foam, but it might leave a piece-of-scotch-tape looking mark on the casting. You could try blending in the edges of it with some of the toilet gasket wax instead of stuffing a glob of wax into the hole. I've only tried this with uncoated patterns; not sure if trapping burning scotch tape fumes inside drywall mud might cause any weird effects. Masking tape works too. Jeff
I mix toilet ring wax and paraffin about 50-50. Seems to be the best of both worlds melted and painted in. Not too sticky but soft enough. Sometimes I mix that with bits or shavings of foam to fill bigger holes. You can even build up pure wax shapes on the surface and they burn out fine. Have used scotch or packing tape for flat spots too.
