Fiber Foundations: Assists and Modifiers.

Assists and modifiers.

A fancy word for assists and modifiers in the dye world is auxiliary. Assists and modifiers are the same materials but with a different intention of use.

Assists and modifiers can be acidic or alkaline.

Example;

1. I use Cream of Tartar as an assist to prevent my alum mordant to clog up at the bottom of the pot.

2. I use Cream of Tartar as a modifier to lower Ph of my cochineal dye bath, to get bright reds.

An alkaline auxiliary will elevate the Ph level in the dye water. Ph is a number, used to indicate the acidity or alkalinity level of a material. Ph 7 is neutral, anything above is alkaline, anything below is acidic. Ph levels are important in natural dyeing as it can influence dye uptake and shade.

You test Ph with Ph test strips or a digital Ph meter.

Alkaline assists and modifiers; (in order of strength)

• Chalk (Calcium Carbonate) – Ph 9.1

Chalk is used as a color changer. If you have soft water with a low Ph, the addition of chalk to your dye bath will make your water harder. Chalk in the dye bath with bring out the best reds in madder and Alder buckthorn. In sappan wood dye the slightly higher Ph also brings out the bright reds.

• Soda Ash (Sodium Carbonate) - Ph 11.6

Soda Ash increases the effectiveness of a mordant on cellulose fibres. As a modifier it can change colours dramatically, just a bit can shift cochineal to purple. Soda Ash is also used to scour cellulose fibres.

• Hydrated lime (Calcium hydroxide) -Ph 12.6

Hydrated lime is a stronger alkali than chalk or soda ash. It is also difficult to suspend in water.

• Lye (Sodium hydroxide aka caustic soda) - Ph 14

Lye is extremely alkaline and that makes it dangerous to handle, try to avoid using it. If you must, use protective goggles and gear.

Acid assists and modifiers:

• Citric Acid, Citric acid is naturally concentrated in a variety of fruits and vegetables, particularly lemons and limes. As with most organic acids, citric acid is a weak acid, with a pH level between 2 and 5. For natural citrus fruits limes have a Ph of 2.8, oranges 3.3 to 4.2.

• Acetic acid (vinegar) Vinegar is mildly acidic with a pH of 2–3. Apple cider vinegar is slightly more alkaline than pure vinegar because it contains more alkaline nutrients. However, it's still acidic

• Cream of Tartar, Ph 3.5, is a by-product of wine making. Use as an assist when mordanting with alum, use as a modifier for acid loving dyes such as cochineal. Cochineal will go from fuchsia to red with the use of Cream of Tartar. Cream of Tartar works best on protein fibres and is not often used with plant fibres.

• Tartaric Acid, Ph 3.6, is also a by-product of wine making.

Tartaric acid crystals are used at the rate of approximately 1 gram per liter to reduce the pH by 0.1 unit. For example, to reduce the pH of a 20 liter (5-gallon) batch of dye from 3.6 to 3.4, you need to add 40 grams of tartaric acid crystals

Tartaric acid and cream of tartar are not the same thing. Cream of tartar is made from tartaric acid by combining tartaric acid with potassium hydroxide. This partially neutralises the tartaric acid, so cream of tartar is less acidic than tartaric acid.

These samples of rhubarb on silk show you how the use of modifiers can influence the hue.

Alkaline and acidic modifiers used in rhubarb dyeing

Using metallic salts as modifiers.

Tannin and post-mordant as a modifier.

There is a huge difference using a mordant as a mordant doing the proper mordant mordanting process, or using it post-dye or post-eco printing as a modifier. Especially ferrous sulfate has a strong effect on most dyes.

When you use a mordants salt such as ferrous sulfate, or copper sulfate, after the initial dye process, it will most likely affect the colour, but it will not improve light fastness or wash fastness in the same way as it would when using it prior to the dye process.

Using ferrous sulfate in combination with tannins will result in different shades of grey and black.

This phenomenon is the reason why tannin rich leaves, on ferrous sulfate mordanted fabric, will leave dark imprints. The higher the tannin/ferrous sulfate rates, the darker the print.

The tannin in the leaf, reacted with the ferrous sulfate in the fabric.

In these samples with marigold you clearly see the difference between mordanting before dyeing and using the ferrous sulfate as a modifier post dyeing.

Mordanted and then dyed with marigold (left) Dyed with marigold and then modified with iron (right)

All the different mordants on marigold, modified post-dyeing with ferrous sulfate.