Griffin Dyeworks & Fiber Arts

Understanding Mordants and Modifiers



Description: Mordant, gray-white to greenish crystalline powder that turns brown when exposed to air, found in ore-bearing rocks, in clays and sands as oxides; one of the basic elements, an ancient mordant. Iron is mentioned in Genesis of the Bible and certainly in use as a mordant by 2000 BCE.
Other Names: Burnt ochre (ferric oxide), burnt ore, copperas, feosol, ferrous sulfate heptahydrate, green copperas, green vitriol, hydrated ferrous sulfate, Indian red, ironate, iron mordant, iron protosulfate, iron sulfate, iron sulfate heptahydrate, iron vitriol, nitrate of iron, Paris green, Prussian blue (ferric ferrocyanide), rust, rouge, Venetian red, [Viking]: iren, isen, isern, [Old]: coperose, couperose, cupri, [ME] coperas, [ML] cuprosa, [L] ferrum, ferreus, [Celt] ysarno, iserno, [AS] irsern, yren, [OS] isarn, yron, yrwn, yzen, [Icelandic] jarn, [Gael] iraruinn, iaruach
Dye Use: Darkens or drabs colors, 'greying' mordant that adds a gray or brown cast to fiber, helps fix tannin on cotton, reducing agent in some indigo vats, rather unpredictable. Too much iron mordant causes harsh, spotty fiber.
Best On: Cotton, linen, hemp, ramie, etc. Use very lightly on wool, silk and rinse very well.
Dye Recipe: Dissolve 1/2 tsp or less iron in 1 c hot water, strain to remove any iron particles, add to 1 gal water, add fiber, simmer gently 10-20 minutes. Sometimes just a pinch of iron will suffice. To help soften fiber, add 2-3 tsp cream of tartar or 1 tsp soda ash, simmer 10-15 min longer; don't boil. Rinse thoroughly; if iron scent is still on fiber after dyeing, rinse with vinegar-water until there is no metallic odor
Safety: Toxic if ingested in large amounts; can irritate sensitive skin; heating iron powder can cause toxic fumes
Disposal: Dilute with water and pour on trees, azaleas, gardenias, and other iron-loving plants
Alternative: Galls or other tannins
Source: Griffin Dyeworks or make your own iron liquor

CODES: c = cup; gal = gallon; lb = pound (weight); tbsp = Tablespoon; tsp = teaspoon / [AF] Anglo-French; [Ar] Arabic; [AS] Anglo-Saxon; [Dan] Danish; [Du] Dutch; [Fr] French; [Ger] German; [Gk] Greek; [It] Italian; [L] Classical Latin; [LL] Late Latin; [ME] Middle English; [ML] Modern Latin; [OE] Old English; [OF] Old French; [ON] Old Norse; [OS] Old Saxon; [Port] Portuguese; [Sp] Spanish; [Sw] Swedish / CE = Common Era; BCE = Before Common Era

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