Grinning Stone face

I bought four molds of different faces several years ago to use for hypertufa (a mixture of concrete, peat moss and perlite) but instead of making them solid, I put a rolled up ball of newspaper in the back of the head so I could plant into them - worked well except that I didn't devise a method to drain the water out and they froze and cracked. However, they were a big hit and I sold many of them, and could have sold more. The bad part is that I neglected the care of the molds and they may be unusable now. Don't use vaseline or any other oil product in them as a mold release! This is a link to the page about the heads; https://www.bluefoxfarm.com/latex-molds-for-hypertufa.html