Unknown substance coating plaster - its not asbestos, right?

[TooCls2h8]

I've got a Baltimore rowhouse built in 1920. I'm prepping the plaster walls for drywall.

I was trying to pick off a cardboard/plastic border that was glued on with some sort of construction adhesive, when I noticed the paint would come right off practically in sheets with a spackle blade, all the way down to the plaster.

There is about 1/8" of this soft, almost fluffy, white/grey stuff coating the plaster, under the paint. It comes right off.

My guess is that its used to soften the look of the plaster and make it look more like drywall - but what is it? Is it hazardous? Anyone know? Thanks!

[HayZee518]

there's a term called "efflourescence" and applies to plaster that is "hot!" By "hot" it doesn't mean that there's any heat, it just has reacted with wallpaper paste. There's a wall wash that turns a pink color when efflourescence is present. KILZ can neutralize the hot spots.

[TooCls2h8]

that's really interesting, there's a lot out there on efflorescence with plaster, and it sounds like what i've got - there was wallpaper under that paint. Good to know. Thanks,

Mike