Thanks a lot for the advice. I will definitely give the blue tape a try. We were trying to do the prints in HIPS for one other reason than the smooth finish. While with PLA you would have to prime and paint to get the models in full colour, with the HIPS you would actually be able to colour the model with Copic markers directly after printing which gives great control and is much simpler. We have since decided to use a matte acrylic spray coating over PLA prints and still use the Copic markers (I will post the results, if you like). I am still dedicated to the HIPS as a material and I plan to do a lot of experimentation until I get it just right. HIPS seems just too good a material to only be used as fill and washed away with limonene.
Thanks again for the help, and as a newbie to 3D printing I am glad to see the Community is so involved.