Following up on a topic from 2011 that I can't respond to. I have this same problem. My snow has turned yellow in some spots on my Christmas layout. It has happen to me twice. Once with a homasote base and once with a foam base. Both were painted white. Elmer's glue 50/50 mixture as the initial base with WS scenic cement as a touch up. I am using WS snow. I honestly think it is the WS cement causing the problem. First time I thought is was old glue but the second time it was a new bottle. I don't think you would see this problem with typical scenery materials. Any ideas? What was the outcome of the original thread?
Thanks,
Chris