When dyes are directly applied to fabric a thickener should be mixed into the dyes to keep them from wicking. Sodium alginate a gum derived from seaweed is generally used for this purpose.
The type of sodium alginate used depends on the fabric.
Type H is a high viscosity, low solids content thickener. This type produces a very thick solution from a small amount of alginate, and is usually used for cottons and heavier fabrics.
Type L is a low viscosity, high solids content thickener. This type requires more alginate to produce a thick solution, Type L is used when high definition is needed. It easily rinses out of light weight fine fabrics such as voile, chiffon, organdy, habotai and other light weight silks.
For cottons or medium weight fabrics
For silks or light weight fabrics
Dyes that will be sprayed through an air brush should be very thin. Dyes that will be painted should have a medium consistency. Dyes that will be screen printed must be fairly thick. If the alginate is too heavy it will not mix well with the dye.
Add 10% to 50% sodium alginate to the dye. Before adding the alginate some thought must be given to the type of fabric, dyestuff used, dye process, and how many applications of dye will be used. Too much alginate will act as a resist and the fabric will not absorb all the dye.
Logwood: For very thin fabric add 20% alginate to the dye.
Catechu: 15% alginate
Sappan wood, fustic, apple bark, peach bark: 10% alginate
Sodium alginate can also added to the mordant.