In the northeast a product called blueboard is the norm. It has an absorbant surface designed to bond well to the plaster surface coat. It's the norm for residential construction here.

^^blueboard

Thank you elunia, and rwiegand, there is no such product in the southeast. I was able to see it on "This Old House" I guess I am going to have to call some plaster people. Thank you both.

You might have "button board" AKA "rock lath" instead of lath which is like early drywall that has holes to serve as plaster keys. It then gets plastered but saves a few steps in the process. It was used a lot in the 40s-50s and often in squares instead of nice rectangles like modern drywall. I have had plaster guys patch it like your contractor did--regular drywall skimcoated to match.

A good drywaller should be able to patch or match plaster if you want to go the cheaper route (cheaper than actual old school plaster). It's hard to find a good plasterer these days!

Iri, thank you for your time, the rest of the house is plaster and I could just drywall it, it's just a toilet room we are sectioning off in a large bathroom. However if you ever have roof leaks the plaster doesn't mold which is a nice bonus. I have a way of making things harder then they actually have to be. It's such a small area I should just forget it. I found Georgia Pacific has a product that says HIGH SUCTION PAPER-FACED GYPSUM BOARDS SPECIALLY DESIGNED FOR VENEER PLASTERS. However it's not available down here, at least not at the bigbox stores. I think I will call them directly tomorrow. Again thank you for your time trying to help me and the explanation of what you have seen. I add that to my knowledge bank. : )

Thanks DeWayne, maybe hardi backer would be good too. Yes, I will give them a call. I went on chat with HD yesterday they have no idea what I am talking about.