I used a scotch / 3M solvent, can't remember whether it was no.1 or no.2.
Agreed about the well ventilated area though. It's heady stuff, and extremely flammable too..! It was a product we used to use at work, so I "liberated" a little bit to help get the garden incinerator going!
No longer allowed to use it in these health and safety conscious days, but being the stores supervisor, I've got some locked away, just in case I get the urge for some more transfer prints.
With regards to these prints, I'm surprised at how well they last. These must be at least 10 years old and don't appear to have suffered any fading at all.