THE FUNCTION OF MORDANTS Most dyes, when applied to fabric, will either wash out or fade rather quickly. These dyes need to be fixed to the fabric, typically using metal salts that become the molecular bond between the fibre and the dye. These salts are not edible salts and although most of them are innocent, they should be treated like chemicals and kept away from children and pets, and use only while wearing gloves and a protective mask. All mordants should be used in well ventilated areas with dedicated pots and utensils that are not to be used for other purposes than dyeing.
HEALTH HAZARDS
Are mordants toxic?
Let it be clear that mordants are not to be ingested and exposure to skin may cause irritation. The mordants in this list are, to my knowledge and extensive research, not a health hazard when used correctly. There are different sites and articles where you can check toxicity of materials, they are mentioned in the back of this book.
The list given here is by no means complete. I have left out environmentally unfriendly or hazardous mordants that I believe have no place in a non- professional setting, or mordants and assists that are just disgusting such as urine and horse manure which were commonly used in old dye recipes.
The most commonly used mordants in natural dyeing:
Alum The sunny mordant Potassium Aluminum Sulfate or Potassium Aluminum Sulfate Dodecahydrate K(Al)(SO4)2 or K(Al)(SO4)2 * 12(H2O) Use at 12-20% WOF Bought either in rock shape or granules or powder. Alum will brighten up all colours. It assists bringing out purple in logwood, and red in madder, and makes all yellows sunnier.
Other forms of alum are aluminium sulfate and aluminium tri-formate. The effect is the same, the use is slightly different, which we will discuss in the modules.
FERROUS SULPHATE
Generally known as; Iron
The Sad Mordant
Ferrous Sulphate or Ferrous Sulphate Heptahydrate
FeSO4 or FeSO4 * 7(H2O)
Iron should be used at 2-4% WOF
Iron gives greys and blacks when combined with tannins.
Iron will make yellows into khaki green, and reds from madder into burgundy red.
Alternative; Make your own iron solution by soaking rusty bits in a glass container filled with 20%vinegar and 80% water.
COPPER
Copper
Sad/Green mordant
Copper or Cupric Sulfate or Copper Sulfate Pentahydrate CuSO4 or CuSO4 * 5(H2O)
Copper brings out the greens and yellows in leaves and dyes, more to the mustard side of the colour spectrum.
Tin Stannous Chloride SnCl2 Use at 2% WOF TIN Tin is considered to be a generally neutral mordant, yet it brightens colours and causes them to pop a bit. It is the only way to get a truly bright scarlet red using cochineal. Use in low concentrations only. I prefer making the solution and applying it in a well marked spray bottle so not to be left with solution that I have to throw away. •
TITANIUM OXALATE Titanium Oxalate - Titanyl-potassium oxalate The Orange Mordant use at 2%WOF A new mordant in the market, It provides a better fixation of natural tannins and bright oranges. In combination with natural dyes, you will get new ranges of shades, especially bright oranges with yellow natural dyes. Titanium Oxalate should be handled with care, the very fine powder is easily inhaled and not good for the lungs. By creating stronger complexes between the fibres and the dyes, titanium mordent contributes to more lightfast and washfast.