I heat pressed on satin the other day. The CWU logo was already silk screened on the stole. I was asked to add the sorority and year. I was a little worried about adding this to the satin, since it was for my clients graduation attire.
I used Siser EasyWeed. I couldn't find any specification for the satin, so tried it out on some sample fabric I had lying around. It pressed well. I had the temp at 305, and set it for about 8 seconds, but no more than 10 seconds. I noticed it started to smoke/steam at about 10 seconds, which kind of had me worried. The fabric didn't burn, it left a depression from the edges of the EasyWeed backing material, so in the future, I will trim it closer to my design. Overall, it worked well. If I do it again, I will try it at a lower pressure setting.