(If possible, use an old saucepan and spoon for this process. The ingredients in cold porcelain aren't toxic, but they can be sticky, so don't use your best utensils!) 

Mix the wet ingredients over medium heat.


Begin by mixing the white glue, water, cold cream, and glycerin in a saucepan. Stir this mixture over medium heat until it's smooth. (You may need to mash that cold cream up a bit in order to get it to dissolve.)

Add the cornstarch and continue stirring.

When the wet ingredients are nice and smooth, add 1 cup of cornstarch. Be ready—the mixture will transform very quickly at this point. Continue stirring. The mixture will rapidly become quite stiff.

 

At first, the mixture will look like cottage cheese...

...and within minutes, it will stiffen into something that looks like mashed potatoes. 

When the mixture forms one clump and has pulled away from the sides of the pan, it's done.

Wrap the hot clay in a clean, wet dish towel

 

 Knead the clay through the wet towel until it's cool enough to handle

Wrap the wet towel over the clay and knead through it. Pause every couple of strokes to pull the towel from the clay, then repeat the process.

Continue kneading, dusting cornstarch on your hands to prevent sticking

In a few minutes, the clay will be cool enough to handle, so you can continue kneading with your hands. Keep a small bowl of cornstarch nearby, and keep lots of it dusted on your hands so the clay doesn't stick. You can also dust the surface of the plate with cornstarch as needed.