Grab two shirts.

Make a line.

Twist, tie very tightly, and rubber band it, or do an accordion fold following the line and rubber band it together....

Let the clothes sit in soda ash for 20 minutes. Next, bleach it and let that sit for 10 minutes or however long you would like. If you want to dye it colors then you can dye it after you bleach it. Make sure the bleach is completely rinsed out because it can hurt the fabric and the color dye....

Wash it with cold water.

Let it air dry.