Lay out your shirt. One with little to no printing on it is preferable.
The printing sits on the surface of the material and thus makes it harder to work with as tarn.
Cut from arm pit to arm pit and cut off the bottom seam.
Save these parts for another project.
If there is printing below the arm pits, then cut off that to.
Fold shirt from side to side leaving about a half an inch of a single layer exposed.
I like to use a ruler and a rotary cuter to cut my tarn. Cut 1/2" or more leaving about a 1/2" uncut on one side. The smaller the width cut, the thinner the yarn, and the more yardage.
You can just use your scissors and cut around and around in a continuous circle. It takes a little longer, but it works.
This is what it will look like after you finish cutting.
Notice the uncut side?
Now open the shirt up so that the uncut section is visible.
Cut one piece to get it started.
Then cut from the next cut line to the next cut line on the other side.
Keep cutting in this manner.
It will make a continuous strip of material.
Now give a little tug (with both hands) to stretch it.
The sides will curl in.
Do this to the entire length of material.
I recently bought a ball winder, however you can just make your own ball. Its easy to do.
The 2 on the outside were cut at a 1/2" width.
The one in the center was cut at an inch width.
If you have a lot of white shirts, you can dye them before cutting them to make more colorful tarn.
I am apart of a RAL (rug-a-long) in the Trash to Treasures Ravelry group (link on the right side of my blog). I am making my rug out of tarn. I crochet 8 stitches into a ring, and then increased as normal to keep it flat. I am using a size J hook.
8 st in magic loop
R2: 2 sc in each chain = 16 sts
R3: (2 sc in chain, 1 sc in chain) repeat = 24 sts
R4: ( 2 sc in chain, 2 sc in chain) repeat = 32 sts
R5: (2 sc in chain, 3 sc in chain) repeat = 40 sts
* Just at the number of sc (single crochet) for each row.*
The total number of stitches is a multiple of the number that went into the magic loop. In this case it is a multiple of 8.