I use Procion cold water (I think procion mx) dyes. To dye in a bag you
have them all tie with rubber bands( tightly) than you soak the cotton
shirts in bucket of pro chem activator aka sodium carbonate about 15 minute
can be longer. I think it is 1/2 cup to 5 gallons. than you can squeeze
out and then hang them to dry or use them wet. The sodium will keep the
shirt ready or activated for quite a while so this can be done and the
shirts done a week later. I mix the colors very concentrated diluting in
hot water and putting salt in. As much as will dissolve. About 1/2 teas
dye powder 1 teaspoon salt and hot water to fill spray bottle. You lay the
shirt on a piece of saran wrap or an opened plastic bag. Spray dye. If you
are suing more than one color tye colors that will make successful third
colors like blue yellow or red/yellow. we would roll it and pop it in a
sturdy plastic bag tie end carefully and sit it in a sunny spot for two
hours. than rinse in cold water till water runs clean. take rubber bands
on and rinse again.
If you want lots of different colors we put saran wrap on the top of shirt
when done as well.. and gently rolled up the shirt so most parts did not
touch each other in a bag. For 3rd grade I doubt they will be so fussy.
Pro Chem Company Somerset Ma. is a great place to get dye quickly.