From Tie-dye Wiki
The spiral fold is one of the most popular folds used in tie-dyeing. It is quite versatile and can be combined with other folds.
 Folding a spiral
Like any other fold, spirals are best made with damp fabric. Determine the center the spiral. Pinch the fabric to about a 1/2 inch height and grasp the fold with a clothespin, between the center tines of a fork, or with something else.
Begin to twist the fabric with the fork, clothespin, or whatever you have securing the center of the spiral. Be very careful if using this method, the fork or other such item can possibly pierce the fabric. Carefully adjust the fabric as you twist to encourage uniform height of the pleats that form with the twisting. There will be a tendency for the pleats to get larger as you go on which creates a depression in the middle where dye will pool forming a muddy mix of colors. To avoid this, after each twist pull the fabric out from the spiral and adjust the height of the pleats. Once you have formed a nice tight center to the spiral, you can remove the fork or whatever you are using and just start working the fabric around the center with pleats at a nice uniform height until all the cloth is in a nice uniform spiral.
 Binding the spiral
If you use rubber bands, simply slip the rubber bands over the spiral from one side, through the middle and to the opposite side. You will need to use several rubber bands depending upon the size of the spiral--6-8 rubber bands __minimum__. Using too few may distort the shape of your spiral and make it difficult to maintain the circular shape. Additionally, be careful to use the right sized rubber bands. If they are too large, they will not hold the spiral together. If they are too small, they will contort the spiral.
With string or other such materials, start by pulling the string under and over the spiral through the center forming a basic knot at the edge. As best you can (a third hand is ideal), cinch the knot tight while holding one hand palm down and fingers open over the spiral to keep it flat. Quickly make another knot forming a double knot. Rotate the spiral slightly and draw the string over the middle to the opposite side, then under.
Again hold the spiral flat, and pull the string from under the spiral firmly. Continue to rotate and work the string around the spiral repeatedly until there is a nice, firmly bound, flat spiral. At the edge of the spiral, loop the string though one of the bindings, cut the string from the spool and tie it off.
 Dyeing the spiral
Dye is generally applied to the spiral as wedges or like slices of a pie with the center of the spiral serving as the intersection. The spiral could be dyed with two colors in two halves, three when divided into thirds, four when divided into quarters, etc. When dividing into 4 or more sections, the same colors could potentially be repeated.
In general, it can be difficult to get the dye to penetrate all the layers of fabric, so the yorker spount needs to be inserted between the folds. It may also be helpful to apply the dye a couple of times. The dye should be applied to both sides of the spiral.
 Classic Rainbow
Many like to try a classic rainbow tie-dyed shirt. It's one of the most basic ways to apply the dye to a spiral fold. Use 3 primary colors overlapping in parts to make secondary colors as well. To do this, apply each color to 1/2 of the spiral overlapping 60 degrees--resulting in 6 colors occupying 60 degrees of the spiral: the results will result in an area of red, purple (where the red and blue overlap), blue, green (where the blue and yellow intersect), yellow, and orange (where yellow and red intersect). The pattern is repeated on corresponding sections of the other side of the spiral. Those already having secondary color dyes may get a similar effect by applying the colors in sections 1/6 the circle in the same order without overlapping.
 Corresponding and Contrasting Colors
Often the corresponding color dye is applied to each side of the same section of the spiral. In other words where red is applied on the to of the spiral, it is also added to the the bottom of the same section of the spiral.
Many variant effects can be achieved using different colors on each side of the spiral. The simplest way to do this would be to apply a different color to the entire top and the enire bottom of the spiral. For example, pink applied on the top side of the spiral and green on the other.
Another effect is to apply a series of colors on the top side of the spiral, and a single color such as black or dark blue to the entire other side. It creates a contrasting backdrop to the spiral. This effect has been termed contrast, stained glass, or cathedral.