The plasterer who, over the years, did pretty much my entire house a room at a time, reckoned that most people could learn to plaster. He worked mostly on the sites where he said the rule of thumb was that it took two houses. They would set a beginner to work on the first house and essentially almost all the rooms would be unacceptable. So it would all have to come off and a proper plasterer would then re-do it. At some point in the second house the beginner would start to get the hang of it and by the end he’d be good enough that most of what he did could be left on the walls and, if they were lucky, even some of the ceilings.
As he pointed out though, most DIYers never have that much to do. Even I only had one house. So we never get good enough to make it worthwhile.
For what it’s worth he also said that far and away the commonest mistakes include i) not using really fresh plaster (he advised going to a DIY store with a really fast turnover), ii) working too slowly so you end up with the stuff in the bucket going off before you’ve finished and iii) for the scratch coat, overworking the plaster - “just slap it roughly onto the wall and let it get a good grip before you go back and set about flattening it”.
My Dad was an accomplished tradesman who could turn his hand to most things.
He would do a bit of making good but wouldn’t attempt a serious plastering job.
‘Always know when to call in a pro’
was his maxim.
