Hi! Thanks for the question. Yes we were concerned about venetian plaster reacting with the heat from the fireplace so we held it away from the main firebox. We never install it immediately adjacent to the glass. In this case we used a quartz product as the immediate surround. Hope that helps!

Thanks for responding! Going to do a similar treatment and wanted to make sure I covered all my bases!

This is the most helpful thread I’ve found on this issue! I’m wondering if there is a max temperature limit for the plaster. We installed a gas insert that (after being on high for several hours) gets the surface directly above the insert to 240 degrees. We had a couple cracks above that area show up - are in the middle of diagnosing the origin of the crack, but want to find a long term solution so we don’t have to worry about how hot the fireplace gets. Any suggestions for material under the plaster to use? Or how to prevent cracking - is it just to keep the plaster away from the opening? (But I’ve seen other pics on Houzz where the plaster goes right up to the enclosure).