Live and learn, this time around I used an old tooth brush rather than my fingers to scrub the resin in soapy warm water. Just to be on the safe side I also gave the model a very slight spray of grey primer to give the paint something to bind to. The results were much better with no paint coming off with the blue tac.
This is always my favourite part of the job, peeling of the blue tac to see what’s underneath. It’s like unwrapping a Christmas present.