The Dyeing Process

Basic equipment

A well ventilated area with water supply and heat source. Kitchens are not ideal as the chemicals used in dyeing are poisonous. If you must dye in the kitchen please ensure that no food preparation equipment is used and that food is not about the kitchen while the dyeing is being done and clean up carefully. When possible I dye outside on a gas camp cooker.

  • Accurate scales: I prefer to use electronic scales that will measure down to 2 gm. Ideally use chemical scales for the mordant and dyestuff as these are even more accurate
  • Stirrers that will not be used for cooking
  • One medium sized pot, one large pot, one large bucket or basin
  • Candy thermometer
  • Rubber gloves / apron

Additional equipment may be required for more advanced projects.

Materials

All natural fibres can be dyed, however they do have different properties. Wool, cotton and silk all readily absorb dyes and are fairly easy to dye but linen can be difficult to get strong colours on. Another issue with the material to dye is whether to dye the raw fibre, the spun fibre or the finished cloth. Dyeing the raw fibre gives the greatest surface area for the dye to be evenly absorbed into the material and with it loose in the pot it is less likely to develop unevenly – but you then need to spin or felt it in order to use it (which is fine if you want to do that). Otherwise you can dye spun fibre or even the cloth – there are many images of medieval dyers dyeing whole cloth so we know that they did this.

Stages of dyeing

Clean the fibre

The fibre must be clean before dyeing or the dyestuff will not take evenly. In the case of wool this means washing away any remnants of lanolin or other stuff. This is called scouring – modern scouring processes use some fairly nasty chemicals – as did medieval scouring. However a gentle wash in wool wash is adequate for most wools.

After washing the wool (or other fibre), rinse it thoroughly.

Before mordanting the fibre it must be brought up to temperature – doing this too quickly can shock the fibre – instead soak it in a basin of warm water, not too hot.

Mordant the fibre

Most (but not all) natural dyes require a mordant. The mordant does two things. The first and most important is that it makes the fibre receptive to the dye. Many fibres will take only a small amount of dye if not first mordanted. Many dyes are less colour-fast unless mordanted. The mordant can also alter the colour of the dye.

The most widely used mordant is alum. Like all mordants, alum must be used with care and can be poisonous if ingested, however it is less dangerous than some other mordants and is a good one to start with. Alum is often used with cream of tartar (tartaric acid) for best results.

It is very important to measure the mordanting chemicals accurately as too much can damage the fibre, and too little will adversely effect your dyeing results. Alum is best used at 10% of dry fibre weight plus cream of tartar at 5% of fibre weight.

  • Weigh the fibre while DRY, measure out your alum and tartaric acid and dissolve them in a small pot of hot water.
  • Heat a large pot of clean water (large enough that the fibre will have room enough to move in it when full) to warm and add the dissolved mordant. Stir well.
  • Add the wet and warm fibre to the pot.
  • Bring the mordant bath to a boil and then simmer (90 C for an hour).
  • If you have time you can cool the fibre in the pot. Otherwise fill another basin with medium warm water – transfer the fibre to this and rinse, then rinse again in cool water, or transfer straight to the waiting dye bath.

Dye the fibre

Different dyestuffs require different treatment. Some require dissolution in alcohol, some need to be soaked for a month, others require fermentation. This is a generic method suitable for most root/leaf/stalk/lichen based dyes but each dyestuff can be treated in a variety of ways to achieven different colours: many recipes exist.

  • Measure the dry weight of the fibre (you should already have done this for the mordanting). Weigh the appropriate percentage of dyestuff (this varies depending on the dyestuff).
  • Break the dyestuff up into the smallest particles you can – this may require grinding or chipping. Some people swear by electric coffee grinders for this. A more period method would be mortar and pestle.
  • Place the dyestuff in a pot of clean water (or you can put it in a stocking in the pot if you don’t want the bother of straining it out later) and boil or simmer it for as long as you have but at least 1 hour.

Warning – In general the longer you boil the dyestuff the more dye you will get out of it however some dyestuffs lose their clarity of colour if overheated – make sure that you read instructions from a reputable source and keep the temperature between 90 and 95 C if it says simmer.

  • Once the dyestuff has boiled or simmered for as long as you desire remove the dyestuff from the dyebath. You must get it all out or you may find that you have patches of darker colour once you have completed the dyeing.
  • The fibre must be thoroughly wet and warm before you add it to the dyebath.
  • Simmer the fibre in the dyebath for an hour or longer/shorter if you want stronger/weaker colour.
  • If you have time you can cool the fibre in the pot. Otherwise fill another basin with medium warm water – transfer the fibre to this and rinse, then rinse again in cool water.
  • Dry the fibre out of the sun (if possible) – if you have dyed skeins of fibre you may wish to hang a moderate weight off them as they dry to help straighten them.

Overdyeing

This is where the fibre is dyed twice (or more) in different colours to achieve different tones e.g. a yellow dyed fibre is dipped in a blue dye bath to achieve a green.

Post-mordantings

This is where the fibre is added to one last mordant bath before washing and rinsing. This is done to change the tone of the dye. For example a quick dip in a solution of iron water will dull the colour, a tin solution will brighten the colour and a copper solution will green it.