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001B Alum_and_iron_mordant_1
Mordants: Fixing the dye colour to fibres
• Aluminum, copper and iron are most common. Chrome and tin are less safe to handle.
• Not all plant dyes require a mordant, but mordants often produce stronger colours
• Mordants also affect the colours achieved.
• Mordanting should be done before the dye process is carried out. This is called pre-mordanting
• Mordanted fibres can be dried, labeled and stored indefinitely before use.
• Fibres do not need to be remordanted if a second colour is being added. If one dye requires mordanting and the other doesn’t, you will need to mordant ahead.
Alum Mordant:
• Most useful of mordants
• Can be used on all fibres
• It is not a poison, but it is an irritant – do not ingest
• 3 types of alum include:
o Aluminum sulfate – sold by garden stores as soil acidifier – if contains brown specs, these are iron particles – do not use
o Aluminum potassium sulfate or potash alum (most commonly used as a mordant)
o Aluminum ammonium sulfate sold as alum in pharmacies – can be used if potash alum is not available, but isn’t as concentrated
Copper Mordant:
• Can be used on all fibres.
• Usually improves fastness of dyestuff
• Can be bought as copper sulfate / blue vitriol.
• Poison - handle with care
• You can make your own copper liquor (see pg 42 Wild Color by Jenny Dean)
Iron Mordant:
• Usually used more as a modifier than a mordant. Iron saddens / subdues dye colours.
• Increases wash and light fastness
• Used in small quantities, because it can weaken fibres
• Can be purchased as iron sulfate / green vitriol
• Harmful if ingested handle with care
• You can make your own iron liquor (see Wild Color – pg 42).
Calculating quantities of mordants:
• Weigh textile fibre to be mordanted. Record.
• Wet the weighed fibre as described previously
• Mordant solutions can be made ahead of time and stored indefinitely.
• Dissolve mordant crystals in boiling water
Use 1 gm of crystals to 10 ml of water (0.04 oz crystals to 2 tsp water)
For example:
10 gm crystals to 100 ml water or 100 gm crystals to 1000 ml (1 litre) water
Mordanting with Alum:
• When using alum as a mordant for animal fibres, use cream of tartar to increase the amount of alum absorbed by the animal fibres
• RECIPE: 8% alum (8 gm or 1 ¾ tsp) per 4 oz (100g) of fibre / 7% cream of tartar (7 gm or1 ½ tsp) per 4 oz (100g) fibre
• Use at least 18 litres of water per 500 gm fibre.
• Fill stainless steel pot with cool water.
• Dissolve tartar in boiling water, and then add to cool water in mordant pot. Dissolve alum in boiling water and ad to mordant pot. Stir well with long handled spoon.
• Add fibres heat slowly and bring to simmer – simmer for one hour, move around gently every once in awhile to ensure even absorption. Make sure fibre stays beneath the surface. – If needed put an old plate on top of liquid to keep fibre submerged.
• Switch off heat and let fibres cool in solution overnight
• Remove from mordant solution and rinse well in cool water
Mordanting with Iron:
• Less frequently used as a pre-mordant
• More commonly used as an after-mordant
• RECIPE: 2% (2 gm or ½ tsp) ferrous sulfate crystals to 100 gm (4oz)fibre
• Follow Alum process except after adding wet fibres, let simmer approx 10 -15 minutes only
• Gently remove fibres, and allow cooling down. Rinse thoroughly.
***Cleaning pots after iron mordanting: clean pots thoroughly, the slightest trace of iron can dull the colours of anything put in the pot later. Some prefer to keep one pot for Iron mordanting only.
