To custom dye a martial arts uniform takes a little work and pre-planning.  Most karate uniforms can not be dyed because the fabric is treated to resist dye process.  ProForce 5oz and 6oz uniforms can be dyed, Sun Uniforms brand dyed uniforms are custom pre-made and Century offers custom built uniforms in different colors.

To dye a ProForce uniform plan ahead for shrinkage.  The darker the dye color such as green or purple the less control you will have over the dye outcome.  Often you may need to dye a uniform more than once using more dye packs to get the color you want.  One kids sized uniform usually takes 2 boxes of dye.  An adult size uniform may need 3 to 4 boxes of dye.  If you used a purple shade than came out to pastel you did not use enough boxes of dye.  To enrich the color you would need to redye increasing the boxes of dye for example from 3 to 4.   

Boil enough water to fill your washing maching.  Put a dye pack in water with salt to dissolve while waiting for water to boil.  When the water is ready, place uniform into your washing maching and fill to a medium-high water level setting.  Add dissoved dye and salt solution with 1/8 cup of laundry soap.  Let your washer run on wash for at least 40 minutes which will mean you need to restart the wash cycle.  Keep in mind the color of uniform you see wet will not be the final color.  Rewash the uniform in hot water again.  Completely dry the uniform to see final color results.  

Dyed uniforms make a fun gift, custome or event apparel.  There are more work than they seem.  Getting the color just right takes some practice.