I attempted some plastering for the first time yesterday. I used Wickes patching plaster on quite a small area 0.3m^2 -ish. I am pretty sure the mix was a bit too wet. Anyway, this morning, there were yellow stains in the plaster. Is this likely to be sulphur and, more importantly, is it a problem? Should I hack it off and try again?
It's a 30s house, the patch had the original wooden battens as a base.
Thanks.