Back to Mordants and Additives
Calcium carbonate (Chalk)
$2.80 – $6.30
Used as a DYE ASSIST or MODIFIER in natural dyeing. Chalk can help to boost the colour uptake on certain dyes, including Madder, Munjeet and Weld, enabling more pigment to bond with the fibres by creating less acidic conditions.
TO USE: calculate amount required for .5% WOF (weight of fibre), which means half a percent. Approximately 1 teaspoon per pound of fibre. Weigh and dissolve in hot water. Add to dyebath before entering fibre. For silk, stir into dyebath after dyeing is complete and taken off the heat, then soak fibre overnight.
Dye solutions containing chalk may be safely disposed of down the drain or just poured outside in the garden.
CAUTION: wear a mask when handling powders.
Related products
Tin Mordant
Used as a MORDANT in natural dyeing, which allows the plant pigments to bond with the fibres.
Tin (Stannous chloride) brightens colours and really makes them "pop". However, it is one of the trickier mordants to use, and rather expensive. Some dyers prefer to premordant with tin, while many simply add "a pinch" at the end of the dye process, and heat the fibre for another fifteen minutes or so, cool and then rinse as usual. The amount recommended for this is only 25% of the usual premordanting amounts, below.
Used mainly on protein fibres such as wool, alpaca, silk. Tin can make fibre feel harsh and brittle, so do not exceed the recommended amounts. Yarns can also easily scorch during tin premordanting. Do not pack the pot too full of fibre! An upturned rack, marbles or stones can help keep yarns off the bottom of your pot.
TO USE: Weigh fibre. Calculate mordant required for .5 to 2% WOF (weight of fibre). Weigh tin and dissolve in hot water. Fill pot with sufficient water for the fibre to move, add tin and stir. Enter fibre. Bring to 180-200°F and hold 1 hour. Stir yarns frequently. Cool, remove fibre and wash well. Dye immediately or dry for later. Some dyers add cream of tartar at 5-10% WOF with tin.
Spent mordant solution may be safely disposed of by pouring in a gravel driveway or path.
CAUTION: wear a mask when handling powders. Wear gloves when using tin, as it can be absorbed by the skin. BEST DONE OUTDOORS or with very good ventilation. Avoid breathing fumes.
Alum (Aluminum sulphate)
Used as a MORDANT in natural dyeing, which allows the plant pigments to bond with the fibres.
This is Potassium aluminum sulphate, the preferred form of alum for use as a mordant. This IS NOT pickling alum and should not be consumed.
Used mainly on protein fibres such as wool, alpaca, silk. Usually used in combination with cream of tartar. Many natural dyers do a premordanting of the fibre with alum, while others add it directly to the dyebath (particularly with loose fibre such as fleece). Also sometimes used in combination with tannic acid to premordant cellulose fibres such as cotton.
TO USE: calculate mordant required for 8 to 15% WOF (weight of fibre) and 4 to 6% WOF cream of tartar. Weigh and dissolve in hot water. Fill pot with sufficient water for the fibre to move, add alum and cream of tartar and stir. Enter fibre. Bring to 180-200°F and hold 1 hour. Stir yarns frequently but fleece only occasionally. Cool overnight, then wash in soapy water and rinse thoroughly. Dye immediately or dry the yarns to dye later.
Spent mordant solution may be safely disposed of down the drain (except for septic systems). It also may be poured around garden plants that prefer acidic soil conditions.
CAUTION: wear a mask when handling powders. Wear gloves when using alum, particularly when rinsing or handling wet yarns as it is very drying to the skin. Best done outdoors or with very good ventilation.
Copper sulphate
Used as a MORDANT in natural dyeing, which allows the plant pigments to bond with the fibres.
Copper tends to take the dyed yarn colours towards the brown and green ends of the spectrum. A natural dye that comes out bright yellow with an Alum mordant will look very different with copper.
Used mainly on protein fibres such as wool, alpaca, silk. Although we love to use copper as a premordant, many dyers simply use it after dyeing to push the colours a different direction. To do this, add only 25% by weight of the usual premordanting amounts. Dissolve in hot water. Remove fibre from the dyebath, stir in the copper solution, re-enter the fibre and heat for another 15 minutes. Cool and rinse as usual.
TO USE: weigh the dry fibre. Calculate mordant required for 2% WOF (weight of fibre) and white vinegar at 40ml per 100g fibre. Weigh copper and dissolve in hot water. Fill pot with sufficient water for the fibre to move, add copper, vinegar and stir. Enter fibre. Bring to 180-200 deg F and hold 1 hour. Stir yarns frequently. Cool overnight, then wash well. Dye fibre immediately or dry for later use. These directions that include vinegar are recommended by Jenny Dean in her various natural dye books. Older recipes tend to use 8% copper sulphate all by itself, as a premordant.
Spent mordant solution is best disposed of on the ground, such as a gravel driveway. Keep well away from tree roots and anywhere that may drain to a pond or water feature, since copper sulphate is toxic to plants, fish and other aquatic life.
CAUTION: wear a mask when handling powders. Wear gloves when using copper, particularly when rinsing or handling wet yarns as can be absorbed by the skin. BEST DONE OUTDOORS or with very good ventilation. Avoid breathing fumes.
Glauber’s salt
Sodium sulphate. Used as a LEVELLER in both synthetic and natural dyeing.
Glauber's salt slows down the colour uptake of the dye, encouraging more even and level strike. This is particularly useful when dyeing soft pastel shades.
TO USE: Calculate amount required for 10 to 50% WOF (weight of fibre), lower amounts for softer shades, higher amounts for deeper colours. Dissolve in hot water and add in stages during dyeing, as the bath temperature rises but before dye strikes.
Dispose of spent dyebath in your usual way. Down the drain is fine.
CAUTION: wear a mask when handling powders.