So I left it too late but these are the tabs I had open to test what I had on hand:
Special Effects book (on google Special Makeup Effects for Stage and Screen: Making and Applying Prosthetics
By Todd Debreceni)
And an understanding that Fuelite is equivalent: http://www.therpf.com/f9/painting-silicone-127065/
The link that Naptha is used for lighters was the clue My fuelite just says it is a petroleum spirit. And it does work really well. The platsil winds up as a very jelly like lump at the bottom so hooray.