Choose a t-shirt that is at least 80% cotton, rayon, linen or hemp if you want bright colors in your tie-dye design. Fabric mixes containing 50% cotton and polyester don't take the dyes as well and will create pastel shades. Avoid 100% polyester or nylon.
Wash and dry your garment prior to dying to remove any commercial sizing that has been added during manufacturing.
The principle of tie-dying is that by folding the fabric, tying it with string or using rubber bands the dye cannot reach the fabric evenly -- creating color graduations and designs.
A "scrunch" pattern is one of the easiest techniques but is perhaps better suited for fabric than a finished garment. Simply crumple the t-shirt into a flat disk and secure with rubber bands.
For circular designs, grab the cloth where you want the center of the design. Lift the t-shirt and slide a rubber band down the tube of fabric that you've just created. Twist rubber band several times to hold in place. The length of the tube determines the size of the circle. Use rubber bands at intervals along this tube to create more circular designs within the larger circle.
To make a spiral, lay the t-shirt on a flat surface and smooth out any wrinkles. Make a small pleat where you want the center of the spiral to appear. Grab the center of the pleat with a clothespin and twist upwards, no more than two inches higher than your working surface. Tie the end of your design with string and leave the clothespin in place as you dye.
Pre-soak the garment in washing soda for 15-60 minutes.
Back in the "old" days, a bunch of friends would get together, decide on the colors of the day and tie-dye the afternoon away in large pots of RIT fabric dye. We simply mixed the dye according to directions and dyed entire items or portions of the t-shirt by dipping it into the dye using metal tongs. It was cheap, spontaneous and a creative statement.
Today, there are a wide variety of fabric dyes available at craft stores, many of which come in squeezable bottles for more exact application. Working on a flat surface, simply spray or squirt the dye in desired areas.
The key to a lasting design is to keep the garment wet while the dye has a chance to react and set. Once you have finished dying, place the garment in a sealed plastic bag for up to 24 hours.
Wash newly dyed items separately three times to ensure that you've removed all unactivated dye. Use laundry detergent and wash first in cold, then warm and. finally, hot water.
Wash your tie-dyed t-shirts separately the first few times to ensure that they are 100% color-fast before washing them with your regular wash.
Wear rubber gloves when dying. Speaking from experience, I can tell you that it takes about a week to get rid of fabric dye from your hands if you don't use gloves.
Create designs on the front and back of your garment separately. The two layers of material are too thick to create an effective design using a single rubber band or piece of string.
The tighter the rubber band or piece of string around the fabric, the crisper the lines of your design. Experiment with looser tying to create softer graduations of color.