put the model in a vac chamber for about a minute or two filled with a very light soapy water solution. for the soap i like to use a drop of dish soap, doesn't matter which one. for the vac chamber grab a foodsaver quick marinator on ebay or amazon. for the vac source use your vac stone mixer with an extension hose or use a c&b vac.
remove the model from the vac chamber, blow it off lightly then use a good medium set alginate. with your spatula push the alginate around the model teeth and any undercuts first, then quickly fill a properly fitting impression tray. (pre fit to the model) then put the two together.
the vac chamber will quickly and thoroughly hydrate any model, even one that has been sitting around for weeks. combine that with the light soapy water solution and the alginate will not stick to the model. you wont get the drag marks when you separate the two. i dup every stayplate and some repairs, as far as cost, time and effort vs results.. i havent found a better way.
good luck, lots of other good ideas here. let us know how it goes.
ps. hey
wire
thank you so much for the pans you gave me. they worked out perfect.