When I do clam shells, I use feather. When I do tarts, I use glass glow. With that said, I use silicone molds, and I have never had any problems getting them out. From what I understand, if you use the metal tart molds, glass glow does not do well in these and you may have a hard time getting them out. You may try a search, I remember there was some discussion about glass glow and metal tart molds. I love my silicone molds because I can make a lot at one time. The tarts will not be as large as the metal molds, you just have to find what is right for you! Good Luck and have fun! Debbie