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.
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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.
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.
Citric acid
Used in place of vinegar, as a MORDANT on protein fibres when working with acid dyes or food colouring. Many production dyers switch to citric acid because buying jugs and jugs of vinegar gets too expensive, and vinegar makes your house smell like a pickle factory. Citric acid is odour free!
TO USE: dry crystals may be easily weighed at 5 to 8% WOF (weight of fibre). Follow dye instructions for the recommended acid amounts. Just as with vinegar, the point at which you add the acid to the dyepot can make a substantial difference in the end results. Same goes for hand painting and other methods.
TO MIX A VINEGAR SUBSTITUTE: add 200g (approximately 1 cup) of citric acid crystals to 4L of hot tap water in an empty vinegar jug. Cap and shake well until dissolved. This makes a 5% solution that can be measured and used exactly the same as for vinegar in your dye recipes.
Dye solutions containing citric acid may be safely disposed of down the drain (other than septic systems). Some dyers use baking soda to first neutralize the spent dyebath.
CAUTION: wear a mask when handling powders. Wear gloves when handling citric acid powder, as it can cause skin burns. Avoid breathing fumes (just as with vinegar): dye in a well ventilated area.
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.