Tie-dying shirts or other items can be a fun project for people of all ages. In order for the dye to bond with the cloth, the article must first be soaked in a mixture of water and soda ash. Soda ash can irritate the skin, however, making it difficult for those who are chemically sensitive to dye clothing. Fortunately, baking soda can be used in it's place without irritating the skin. In order to create bright, vivid tie-dye colors, you must first pre-soak the cloth in a mixture of baking soda and hot water.
Place the items you plan to tie-dye in a washing machine. Add a 1/2 cup of baking soda for every shirt you plan to dye, or a full cup of baking soda for larger items, such as sheets.
Turn the washing machine on hot, then spin dry. This will allow the shirt to soak in baking soda without the machine removing all the powder. Prepare the tie-dye, while you're waiting for the washing cycle to finish. This may include mixing together the dyes or setting up an area where you plan to dye the items.
Take the items out of the washing machine as soon as it finishes the cycle. The fabric will still be wet and warm, this is normal. Following the instructions on your tie-dye kit, to dye the items.
Place the tie-dye item in a plastic bag when you're finished. This will keep the item wet, allowing the baking soda and tie-dye to bind into the shirt.
Place the bag in a warm location, such as a garage or on top of a dryer. Wait two days. This is longer than most tie-dye kits say; but this is required if you're using a baking soda soak instead of soda ash. Once the two days are up, take the item out of the plastic bag and rinse it in the sink, until the water runs clear.
Wash your tie-dye items in a washing machine with hot water. There's no need to add baking soda this time as there will already be baking soda left on the shirt from the previous soaking. Once the washing cycle is done, move the item to the dryer and dry as normal.
Remove the tie-dye item from the dryer. The colors may have faded a little, but this is normal. Once the shirt has been washed and dried, it requires no other treatment and is ready to wear.