Back to Mordants and Additives
Soda ash
$4.40 – $8.00
Used with fibre reactive dyes as a colour FIXATIVE. Soda ash raises the pH and allows the dye to bond with the fibre. Generally used only with cellulose (plant) fibres such as cotton or flax. Also known as washing soda or sal soda, though this is a more pure form that the washing soda sold in supermarkets.
Also sometimes used in natural dyeing to create more alkaline conditions, and thus altering the colour with certain plants. Extensively used for indigo vat dyeing.
TO USE: Follow dye manufacturer’s directions for amounts and timing.
Dispose of spent dyebath in the usual way, most likely down the drain.
CAUTION: Wear a mask when handling powders. Wear gloves, can be a skin irritant.
Related products
Thiourea Dioxide
Sometimes called Thiox. Used in the INDIGO VAT dye process, thiox removes oxygen from the vat solution, allowing the indigo to work its magic. Thiox is also a colour remover, and is used for that purpose in discharge dyeing, to create white patterns on a coloured background.
TO USE: Follow the specific indigo vat recipe, for amounts and timing.
Dispose of spent dyebath in the usual way, most likely down the drain.
Thiourea dioxide has a shelf life but it's longer than some things you read might indicate. If the powder has a distinctive yellow look, it has probably oxidized to some degree and may no longer be effective. Store in a cool, dry place out of the light i.e. in a cupboard in the house, not out in the garage.
CAUTION: Should be done OUTDOORS ONLY or with excellent ventilation. Avoid breathing fumes. Wear a mask when handling powders. Wear gloves.
Urea (Ammonium nitrate) – 250g
Price per 250g (8.82 oz) container.
CANADIAN SHIPPING ONLY. Limit of 1 per order. We stock Urea in larger packs, including 500g and 1kg sizes available for pickup at the shop only. PLEASE CONTACT US for availability and prices: [email protected]
Due to the potential use of urea as an ingredient in explosives, we wish to handle the distribution of it carefully. Absolutely NO international orders!
We also cannot, by law, supply Urea to those wishing to use it as a nitrogen fertilizer for home garden or agricultural application.
Used mainly with synthetic dyes as an ASSIST, urea helps to open up fibres and allow for better dye penetration, and also keeps the fibre wetter for longer during direct application of dyes. This is a soluble form of urea that dissolves easily in hot water.
TO USE: Follow any of the dyebook directions for cold pad batch dyeing.
Dispose of spent dyebath in the usual way, most likely down the drain.
CAUTION: Should be used with good ventilation. Wear a mask when handling powders. Wear gloves.
Aluminum acetate
May 26/22 - back in stock, finally!
Used as a MORDANT in natural dyeing, which allows the plant pigments to bond with the fibres.
NOT THE SAME AS ALUM!! Aluminum acetate is used as a one-step mordant on cellulose (plant) fibres such as cotton, linen and well worth experimenting with on rayon fibres (including Tencel), bamboo, ramie, hemp and others. This is a more expensive but faster means to get natural dyes to stick without the more traditional alum/tannic acid premordanting method.
TO USE: weigh dry fibre and scour if needed (especially cotton). Calculate mordant required for 5% WOF (weight of fibre). Weigh and dissolve in hot water. Fill pot with sufficient water for the fibre to move, add mordant and stir. Enter fibre. Bring to 190-200°F and hold 1 hour. Stir yarns frequently. Cool overnight, then wash well. Dye immediately or dry for later.
Spent mordant solution may be safely disposed of down the drain (except for septic systems). It also may be diluted and poured on the ground, for instance on a gravel driveway or path.
CAUTION: wear a mask when handling powders. Wear gloves when handling powder or solutions, particularly when rinsing or handling wet yarns. 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.