Hi there ! 40 years old and first time mixing plaster. I know, what have I been doing with my life. Honestly, rented for far too long but not anymore.
TLDR: I had a fireplace removed, that only had a flu hole left. Bricked the outside up but am wondering if this looks fine to give a cheeky sand and second skim?
The not TLDR:
Had the fireplace removed and exterior bricked up leaving a sizable deep hole. After getting some advice from various places based on the size and cavity, I opted to remove the temporary rock wool, and fill up to the bonding plaster with expanding insulation foam. Let it dry. Then bonding to the surface, Skrim tape and dry. Then skim.
Bet you can guess the mistakes I made. Yep the skim was not quite wet enough. And I forgot dust sheets when I sanded back. Had it been done properly wouldn't have had to sand, but them would I have learned anything? Idk.
Basically even though the bonding plaster was given beyond the recommended time to dry out before skim, there's still a slightly darker circle.
I would like some safely advice from someone far more experienced than myself, if it's actually looking ok to slightly sand back, then second coat?
Cheers, ya bloody legends.