Name: katy
Message: Hi Paula,

I looked all over your site for this, but didn't find anything so please excuse if you've already answered this somewhere!

I'm a fashion designer and currently trying to dip dye/gradient some bamboo fabric (similar to these techniques). 

I'm using MX reactive dyes and have experience working with them. I think I've figured out how to get multiple colors merging together, but I'm running into problems with the gradation from color to white (like the red dress in photo). I can get the gradation okay, but I'm not sure how to create that technique and still have the fabric in the dye  & soda ash long enough for it to react and fix properly? 

Thanks for any help! I really appreciate it and love your site!

Try these instructions from the February 12, 2008 posting I made on the Dye Forum:

1. The fabric must be prescoured to remove any finishes left from spinning or weaving the fiber. Wash it in the hottest water available, with extra soda ash (to boost the cleaning) and Synthrapol or another detergent. The fabric must be 100% cotton (or another natural fiber such as silk, linen, or rayon).
   
2. Weigh your fabric to determine how much dye you will need. For one pound of 100% cotton fabric, you will need about fifteen grams of dye. If you like, you can mark one end of your fabric by pinning a large stainless steel safety pin to it before you begin to dye it. You can also use safety pins to mark evenly spaced lines on the fabric where you will change from one dye concentration to the next. (I cannot emphasize enough how important it is that any pins be made of stainless steel, not chrome-plated steel which can rust!) Or you can sew across the fabric in a very wide basting stitch, using a contrasting color of polyester thread, which you will remove afterwards, as a marker.
3. Predissolve your dye in water. (You can use Procion MX dye for up to a week or so after you have mixed it with just plain water, without any soda ash; after that time, however, the dye will gradually become slightly weaker.) Mix 6 teaspoons of dye, or 15 grams of dye, into one cup (250 ml) of water. Use more for a darker range, or less for a paler range. Knowing exactly how much to use with your color choice will require doing some testing.
4. Predissolve your soda ash in water. Mix 7 tablespoons (65 grams) of soda ash with two cups (500 ml) of warm water. (It will take longer to dissolve if you use hot or cold water.) If you have hard water, add a teaspoon of water softener (sodium hexametaphosphate, see "Dyeing with Hard Water") to the water first, to prevent the formation of insoluble white calcium carbonate or magnesium carbonate.
5. Urea can be used to help keep fabric moist even after it is pulled out of the dyebath, allowing for further reaction between the fabric and any dye that is in it. Set aside one pound or 500 grams of urea to add to your dyebath. Urea is inexpensive, about a dollar per pound, if you buy ten pounds from your dye supplier. Using urea in this particular process is optional.
6. In a large (4 or 5 gallon) plastic bucket, make a dyebath containing only enough dye to create a very pale color. Scale the following quantities up or down based on the amount of fabric you are dyeing at a time. I will assume that your entire panel of fabric weighs one pound. Mix two pounds of salt with two and a half gallons of warm or lukewarm water, stirring until it is dissolved. Add one pound of urea and stir until dissolved, then add one-eighth of a cup (two tablespoons) of your dye solution. Stir and then add your fabric. Stir the fabric constantly for five to fifteen minutes, to make sure the dye penetrates the fabric smoothly so that the color is not mottled, then move the fabric to one side of the bucket and hold it there, while adding all of your soda ash to the water. Don't pour the soda ash directly onto the fabric. Now stir the fabric constantly for fifteen minutes while the pale dyebath reacts with all of the fabric in the presence of the soda ash. The soda ash is the dye fixative. The salt does not fix the dye, but it aids the dye to leave the water and cling to the fabric temporarily.
7. For the next step, you will remove that part of the fabric which you wish to keep the palest shade. Wearing long sturdy rubber gloves, locate the safety pin you used to mark one end of your fabric. Pull the end of the fabric out, leaving the majority of the fabric in the dyebath. Squeeze the wet dye from the fabric as much as is practical, for neatness's sake. Allow the fabric to hang into another bucket, or, using plastic-ended clamps or plastic clothes pins, attach the end of the fabric to a hook (such as a plastic clothes hanger) so that you can hang the fabric up somehow, leaving three-quarters of the length of the fabric in the dyebath.
8. Now, while holding the fabric that is still in the dyebath to one side so that you do not pour dye directly onto it, add more of the dye to the dyebath and mix it in. For this next step, you will want double the concentration of the dye that you used in the first step. Add one-eighth cup, or two tablespoons, of your dye mixture to the dyebath, the same quantity that you added in the first step. Swish the fabric around in the bucket of dye, moving it from side to side, doing your best to allow all of the remaining fabric equal access to the dye. After another fifteen minutes, or more, depending on how impatient you are, you should, as before, pull more of the fabric out of the dyebath, squeezing the dye and water out as much as is practical. At this point you have completed two shades of the dye, the palest and the next palest. Do not allow any of the already-dyed fabric to fold over upon itself, as dye may still transfer from one section to another at this stage. Hanging it up is safest.
9. For the next step, you will again double the amount of dye in the dyebath. Since you have already added a total of one-quarter cup, out of a total of one cup of dye mixture that you prepared, now you want to add another quarter of a cup. The total dye concentration is now four times the initial dye concentration in the dyebath. Swish the fabric around, as before, for fifteen minutes or longer. Pull out the third quarter of the fabric, squeezing the dye and water out as before. You now have only one-quarter of the material remaining in the dyebath.
10. For the final step, you will once more double the concentration of the dye in the dyebath, by adding the remaining half-cup of dissolved dye. Hold the fabric to one side as before, so as not to pour dye directly on the fabric, and mix the dye into the dyebath. Stir the fabric back and forth to keep the color as smooth and even as possible. You may leave the fabric to react longer if you wish. Keep in mind that, while the fabric is wet with the dyebath, it looks considerably darker than it will after you have washed and dried the fabric.
11. After all of the dye reaction has completed, wash the fabric to remove the excess unattached dye. Wash it once in cool water to remove the salt and soda ash, then wash it in the hottest water available, 140°F or hotter. Soaking the fabric makes a more efficient use of hot water. You may need to wash two or more times in hot water to remove all of the excess unattached dye, especially if your wash water is below 140°F.

To summarize, the first part of the fabric was dyed with 1/8 of the total amount of dye. The second section was dyed for another fifteen minutes with a total of 1/4 of the dye. The third section was then dyed for another fifteen minutes with a total of half of the dye. The last section was then dyed for a final fifteen minutes with the total dye concentration. In fact, since each increment of additional dye was applied to a smaller amount of fabric, the total effective dye concentration increased even more. This allows for a wide range, from a very pale shade to a very dark one. If you want the contrast between the first shade and the last one to be less, then you would adjust the amount of dye added in each step accordingly. If the change between the four color steps are too obvious to suit you, you'll need to remove the fabric in smaller increments, in a greater number of steps, adding a smaller amount of dye at a time.

If you will be dyeing all of your fabric from the same jar of dye, then you can do fine by measuring your dye by volume, by the teaspoonful. However, if you will be using more than one jar of dye as time passes, and yet want consistent results, you will need to weigh your dye, on a sensitive scale that distinguishes 0.5 gram or smaller differences. Dye powder is made to a standard strength per weight of dye. One dye lot may be much denser or more fluffy than another batch, so volume measurements will not be consistent from one jar of dye to another. Also, for reproducible results, make a note of the temperature of your dyebath at the beginning and the end of the dyeing process, and of exactly how many minutes you spend on each step.

Note that at the end of the detailed instructions in that posting is a briefer description of an easier method:

A simpler method is simply to make up a series of bottles of dye as for tie-dyeing, starting with one bottle that is full-strength, diluting half of it with an equal quantity of water for the half-strength bottle, diluting this one half-and-half to make the quarter-strength bottle, for as many steps as you like. Then presoak the fabric in soda ash, lay it out flat, and paint, squirt,or spray on the dye in stripes, in order, deepest to palest. The results will not be as smooth as in the method above, but it's quicker and easier. This is the method I've used most, myself.

If you include urea in your mixture, as a humectant, the fabric will stay moist longer. The fabric will continue to react with the dye as long as there is unreacted dye, soda ash, and moisture in the fabric.