Please see below the instructions for curing clay for the second group.
“Into a preheated oven, at 180, put the design onto a shallow tray or similar, coloured side up. I put some tin foil onto the rack that I use for cooling after baking and put the design onto that. The reason I didn’t put it into a tray with sides is that I couldn’t see what was happening. When it hits the heat, it will curl up, almost like it is going to go over on itself, but it then unfurls and when it becomes flat, take it out of the oven and let cool. The instructions said to give it three minutes, but that was too long in my oven, so I watched it carefully and it was ready to come out after 14 seconds, others have reported that it took up to a minute. It will shrink a lot and will get much thicker and stronger. When it’s cool, thread the key ring or string on and it’s ready for use. If it’s still a bit wrinkly or curved when it comes out, you can immediately place something heavy on top to help flatten it. Or you can return it to the oven but it likely will take a bit longer the second time.”