Prepping! Get your silkscreen and squeegee out and tape your fabric down. Mix up the thiox paste (recipe on Flickr). Boil some water for the soda ash.
Getting ready to steam your fabric. Get butcher paper or thin, non-fusible interfacing and fold the fabric up in it so that the fabric never touches itself. Fabric on fabric is bad! Wrap it up in as small a package as possible. Get a pot big enough to hold a metal strainer and the bundle. Put the metal strainer upside-down in the pot. Pour about an inch or two of water into the pot and put it on the burner to boil.
Once the water is boiling, put the fabric bundle onto the strainer so that it is not touching anything but the strainer. Put a towel or scrap fabric on top and put the lid on. Let it boil in there for 12-15 minutes. VERY GOOD ventilation is necessary. Do it outside on a hotpan if you have to, this stuff is not good to inhale. After the time is up, take the bundle out WITH TONGS! Unwrap your little bundle after it has cooled for a minute or so and it is safe to touch.
Admire your beautiful fabric! Hooray! Rinse it really well with warm water (the red is a bowl) and then hang it to dry.
Hooray, you did it!