The original plaster in my kitchen is a very, very smooth substance. Modern paint won't adhere. The 'original' paint shows through, but I've had to skim coat it so I can prime and then paint.

I'm sure I've violated some historic plaster commandment....'thou shalt not skim coat original plaster walls...'. But, I don't know what else to do.

It's too late now as it's done, but this is only one room and I can mend my ways for the next room.

Picture is below to help clarify.

The chunks are wallpaper remains on the blue paint
(probably from 1974)...the green guessing 1940?...the yellow original 1920 and in the center the 'beige' is the original plaster.

Thanks for any help!

Plaster is usually very easy to paint, even with latex.

Even if you try to skim coat a bonding agent may not stick either (they are just thin glue).

What is calcamine? I've never heard of that. What was the original purpose of it used for? How would you 'fix' it to ready it to paint?

You may be correct, because in some areas, even the plaster didn't stick. I had to sand it, then replaster and then finally prime.

Thanks again!!

Not a good idea unless there is no other option.
Sanding plaster permanently damages the surface, and you should have the multiple layer checked for lead before even considering sanding them off.

While most lead is lead acetate used as a drier and gloss improver, it may be present in very old houses as lead oxide pigment.