Monday, January 18, 2010


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

4 tsp (18 Grams) sodium alginate Type H
1 liter water

For silks or light weight fabrics

10 tsp (40 grams) sodium alginate type L
1 liter water

Slowly sprinkle sodium alginate over the water and mix in a blender until smooth. Let the mixture stand for at least 1 hour to thicken. Stir again. The thickened alginate can be stored in the refrigerator. This will make a stock solution that can be added to the dyes when necessary. The alginate can be thinned with water depending on the technique used.*
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.
For very heavy fabric use 25% to 30%.
Catechu: 15% alginate
Sappan wood, fustic, apple bark, peach bark: 10% alginate

If there are large color areas, then 20% alginate is used. If many applications of color will be applied then lower the amount of alginate added to the dye. After the 5th application use no more sodium alginate. Too much sodium alginate will not allow for any absorption of color or mordant.

Sodium alginate can also added to the mordant.
Alum: 0.5%

Iron: 20%

Copper 0.5%: 10% or Copper 2%: 15%

Tin: 10%

   Chrome: 15%


Kit said...

This is very interesting. I have not used alginate to thicken natural dyes but have tried gum tragacanth, which was quite disappointing but I expect I need to work with it a bit to improve the results. I read that sodium alginate didn't work so well with natural dyes but perhaps I will try it now after reading your post.

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