I love Crayola Model Magic craft compound. It's light weight, not toxic, air dries and is kinda bendy. It has so many uses and potentials. The draw back has always been that if it dries before you want it to then you are out of usable clay! When it was first introduced, they sold it in plastic bags that could be zip locked after opening. Too many times I would come back to use the clay and find it all dried up, even after closing the bag! I have even found unsold bags in the store that have dried compound in them!! No point paying for something you can't use!
Things got better then they started selling them in small and large tubs. The shelf life of the clay increased. However, I never fully got over being curious about how to soften the clay for reuse. I am a cheap skate and live frugally. I wanted to be able to soften and reuse this clay!! After finding a large lump of newly purchase white just laying around (thanks, kids!) I got determined.
I popped some in my mouth to see what it tasted and felt like. It is slightly sweet and has no chemical taste. It is slightly gritty like toothpaste, a very fine grit. I inspected the newly softened blob and could see cellulose like fibres. It stuck together slightly, but not as much as the original product. I then decided to do the same thing but on a larger scale.
I put some small pieces in my little food processor and ground it up into small bits. I then added a small amount of very warm water and mixed it further until it formed into a ball. I then took it out and added a dollop of wood glue (any white glue would work) and mixed by hand. At first it was lumpy like oatmeal, but after about 10 minutes it became smooth. It is nearly like the original state, just not as fluffy and air filled. Hallelujah! I have found a way to soften and reuse this stuff!!
Feel free to do this yourself. You might find adding the white glue is unnecessary, but it does help it to stick together better. My conclusions are that this compound is made of a very fine cellulose mixed with calcium carbonate powder and some polymer glue (white glue). How they get it fluffy is a mystery. I don't think they use baking soda, the clay is not salty at all. They may use a gas when mixing or may just beat it and incorporate air. Well, I gotta go. I have some model magic to play with!!