Is the murphy's for a release agent Peg? If so, PAM cooking spray, or it's equivalent should do the job for that.

Hi Crete Artisan, I am trying to make first a POP leaf casting, and then use it to make a re-useable silicone mold using Marlinska's Photobucket tutorial as a guide. (Thank you Marlinska). She uses the Murphy's as the release agent between the POP master and the silicone mold.
I recently found this GW posting by Nofu which seems very thorough.
"I personally like dry mold releases rather than greasy ones. For porous materials like plaster, I like to buff in several coats of Johnson's paste wax, leaving only a micro thin layer on the surface and then allowing it to completely haze over before making the mold.
For non-pourous surfaces, like glass, I take Ivory dish soap and mix it 1:3 with distilled water. Use a soft artist's brush and swish the sudsy mix over the surface of the model while drying with a blow drier in the other hand. The result should be a thin soap film that is relatively dry to the touch.
Petroleum jelly (Vasoline) will also work, but is messy to clean up. I don't like PAM or other cooking sprays.
Silicone sprays make great mold releases for everything EXCEPT silicone. They tend to become part of the mold and may actually increase adhesion.
Also avoid petroleum based lubricating sprays. They are messy and make it difficult to brush the silicone over the surface evenly.'
From what he says, I would be better using a wax paste rather than a soap-based release? That will be the next thing I can't find here, sigh....