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Use Iron Powder

IRON POWDER (Ferrous Sulphate) can be used alone as a mordant – as a colour shifter and to increase lightfastness when used in combination with other natural dyes. It is a versatile ingredient for the natural dyer.

You can add it directly to a dye bath – mordant with iron or iron and alum or tannin.

It is very strong and a little goes a long way. The colour results can be dramatic. It reacts with dyes that contain tannin and produces dark browns and greys when combined with tannin-rich dyes.

Pomegranite with iron yields a dark olive green.

Madder with iron yields a deep greyish purple.

Tannin with iron yields a grey- purple.

Cutch with iron yields  a rich chocolate brown.

Beware – iron will stain surfaces, hands and clothing.

Do not dispose of in waterways, lakes or streams.


Suggested quantities:

For a light shade calculate 0.25% WOF

For a medium shade calculate 0.5% WOF

For a dark shade calculate 1- 3%  WOF

Protein fibres can feel harsh after an iron mordant so use the least amount of iron possible. and the lowest temperatures.

Cellulose fibres mordant well with iron so you may use a higher percentage if you wish and a higher temperature.

Iron baths used for colour shifting may be reused several times.

To make an iron solution for mordanting, colour shifting or spraying.

Weigh or measure iron into a non-reactive container.

Add 225 ml of cold water and stir well until fully dissolved. You may strain out any undissolved grains of iron a coffee filter paper or similar.

The iron sloution is ready to use. You can add it to a dye bath or put it in a spray bottle or use for eco printing.

Remember to follow the safety guideline.

It will store well at room temperature in a covered jar . Stir before use. Keep away from children and pets.

Mordanting and colour shifting of yarn, fibre or fabric.

Fill a dye pot with enough water to hold fibres and add the iron solution and stir well.

Add fibres – stirring often for the first 20 minutes – make sure the material is fully submerged in the iron solution.

Heat the iron mordant bath to 130 degrees F and hold for 30 minutes, stirring carefully and constantly to avoid streaking.

Remove from heat and leave to cool enough to handle easily.

Rinse thoroughly in cool water. 

For colour shifting – immerse your fibres in the cold iron bath after you have first dyed your fibres a base colour. Start to heat up the dyebath.  Carefully watch your fibre or yarn and remove it when the iron has shifted to the colour desire. This may only take a few minutes and your iron bath temperature may still be cold or slightly warm at this point as this reaction works quickly.

Cool the fibres and rinse in cool water.   

If you want very dark grey shades, leave the fibres in the bath and raise the temperature to 130 degrees F – removing it when it has reached the shade you desire.

Cotton, linen and hemp can tolerate higher temperatures and you can raise the temperature to 180 degrees F for darker shades.


Safety Guidelines