I cannot get anyone to answer this question, even though I have contacted many mfg's. Are sheetrock mud and plaster the same thing? Is one superior to the other? Is current plaster very different from 1840 plaster? How do you patch old plaster from the Texas frontier, when they likely burned their own limestone rocks to make it? What is the best plaster product to use? Keep in mind that NO-ONE in Texas has plaster normally, so finding a suppler is iffy. What we have is sheetrock. I used sheetrock mud to patch this plaster,and wonder if I can skim coat it if necessary and have it last. Thanks for your help.