Unfortunately no picture, but it is something that looks like white-painted masonite boards with narrow milled grooves straight through. They are usually found on ceilings and walls in, for example, shopping centers, I assume the grooves are for soundproofing.
Does anyone know what I mean and where I can get these boards?
The regular perforated ones with round holes are ugly and have too much perforated surface for good absorption.
Does anyone know what I mean and where I can get these boards?
The regular perforated ones with round holes are ugly and have too much perforated surface for good absorption.
Are you thinking of acoustic panels? They come in many different variations, including slotted panels.
Yes, indeed it is! Didn't think it was plaster.