need some help i’m using the Silmar 249 Clear Polyester Surfboard Resin for overlay and it looks good when it dries but once i add the surfacing wax aid and sand it, when it dries it leave milky looking spots. Am I doing something wrong? thanks
how long are you letting the resin dry for and at what sort of temperature?
i’m lettiing it dry for about 3 days and the temp is around 73 degrees dry and sunny.
Must be nice 
Ive ran into this problem myself. Its the wax(sanding aid). Make sure you are putting the right amount in the resin. I think it calls for 20 drops per ounce, after i encountered this problem, i dropped it down to 10-15 drops per ounce. If you put too much, it just takes longer to remove the top layer of wax. Just keep sanding, it will come out eventually.
Either that or not shaking the can enough to mix it or the can was too cold to begin with in temperature.
^^^ yeah, that wax additive is a nightmare when its too cold, it gets thick and its a big headache to sand the top layer off. Ive had so many problems with that stuff. If its too cold, its left little flakes in the finish, and by the time you sand them out, youve burnt through and hit the cf. Had that happen a couple of times, since then i strain in through some cheese cloth before i mix it into the resin. Havent had any problems since.