{"title":"Alum \u0026 Iron Mordants","description":"\u003cp\u003eAlum and iron are the two essential metal mordants in natural dyeing and eco printing. \u003ca href=\"\/products\/aluminium-potassium-sulphate-mordant-modifiers\"\u003ePotassium alum\u003c\/a\u003e keeps colors clear and bright on wool, silk, cotton and linen. \u003ca href=\"\/products\/iron-ferrous-sulphate\"\u003eIron (ferrous sulphate)\u003c\/a\u003e is used in small amounts to \"sadden\" colors: yellows turn olive, reds turn plum and tannins turn grey or black. The \u003ca href=\"\/products\/cellulose-mordant-kit-cotton-linen\"\u003ecellulose mordant studio kit\u003c\/a\u003e bundles the steps for plant fibers.\u003c\/p\u003e\n\u003ch2\u003eHow to mordant with alum\u003c\/h2\u003e\n\u003cp\u003eWeigh your dry fiber, dissolve alum (typically 10–15% of fiber weight for wool, often with \u003ca href=\"\/products\/cream-of-tartar\"\u003ecream of tartar\u003c\/a\u003e) in hot water, add the wet fiber and heat gently for about an hour. For cotton and linen, apply a \u003ca href=\"\/collections\/natural-tannins\"\u003etannin\u003c\/a\u003e first, then alum.\u003c\/p\u003e\n\u003ch2\u003eUsing iron as a modifier\u003c\/h2\u003e\n\u003cp\u003eAdd iron after dyeing in a separate, weak bath, at 1–2% of fiber weight. In eco printing, a light iron blanket or dip makes leaf prints darker and sharper. Too much iron can make wool harsh, so start low and rinse well.\u003c\/p\u003e\n\u003ch2\u003eFrequently asked questions\u003c\/h2\u003e\n\u003ch3\u003eCan I use alum and iron together?\u003c\/h3\u003e\n\u003cp\u003eYes. Alum is the base mordant, and iron is used afterwards as a modifier to darken and deepen color.\u003c\/p\u003e\n\u003ch3\u003eIs iron safe for wool and silk?\u003c\/h3\u003e\n\u003cp\u003eIn small amounts, yes. Keep the bath weak and the time short to protect protein fibers.\u003c\/p\u003e\n\u003ch3\u003eWhich alum is best for cotton?\u003c\/h3\u003e\n\u003cp\u003ePotassium alum works well after a tannin bath. The cellulose mordant kit gives you a tested method for cotton and linen.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eExplore more:\u003c\/strong\u003e \u003ca href=\"\/collections\/mordants-and-assists\"\u003eAll Mordants \u0026amp; Assists\u003c\/a\u003e · \u003ca href=\"\/collections\/dye-assists-and-modifiers\"\u003eDye Assists \u0026amp; Modifiers\u003c\/a\u003e\u003c\/p\u003e\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"Can I use alum and iron together?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes. Alum is the base mordant, and iron is used afterwards as a modifier to darken and deepen color.\"}}, {\"@type\": \"Question\", \"name\": \"Is iron safe for wool and silk?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"In small amounts, yes. Keep the bath weak and the time short to protect protein fibers.\"}}, {\"@type\": \"Question\", \"name\": \"Which alum is best for cotton?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Potassium alum works well after a tannin bath. The cellulose mordant kit gives you a tested method for cotton and linen.\"}}]}\u003c\/script\u003e","products":[{"product_id":"iron-ferrous-sulphate","title":"Iron (Ferrous Sulphate)","description":"\u003cp\u003e\u003cstrong\u003eIron (ferrous sulfate)\u003c\/strong\u003e is the classic \"saddening\" mordant and color modifier in natural dyeing. A very small amount shifts natural dyes toward deeper, cooler tones: yellows become olive and khaki, madder reds turn plum and purple, and tannins such as \u003ca href=\"\/products\/oak-gallnut-powder-green\"\u003eoak galls\u003c\/a\u003e turn soft gray to black. Iron also improves the light fastness of many natural dyes.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSize:\u003c\/strong\u003e 50 g (1.76 oz). Because iron is used in such small amounts, 50 g treats a lot of fiber.\u003c\/p\u003e\n\u003ch2\u003eHow much iron to use\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eAs a modifier (afterbath):\u003c\/strong\u003e 0.25% WOF for a light shift, 0.5–1% for medium, up to 2% for dark shades. For 100 g of fiber, that is just 0.25–2 g.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAs a mordant:\u003c\/strong\u003e 2–4% WOF, mainly on cotton and linen. Never use more than 4%, as too much iron weakens fibers.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWool and silk:\u003c\/strong\u003e keep to 1% WOF or less. Iron can make protein fibers feel harsh and brittle.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWith tannins for grays and blacks:\u003c\/strong\u003e treat the fiber with tannin first, then give it a 0.5–2% WOF iron bath. Repeat for darker shades.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eWOF means the dry weight of fiber. Not sure what that means? Read our \u003ca href=\"\/blogs\/news\/mordants-for-natural-dyeing\"\u003eguide to mordants for natural dyeing\u003c\/a\u003e.\u003c\/p\u003e\n\u003ch2\u003eHow to use iron as an afterbath\u003c\/h2\u003e\n\u003col\u003e\n\u003cli\u003eDye your fiber as usual, for example with \u003ca href=\"\/products\/madder-root-powder\"\u003emadder\u003c\/a\u003e, \u003ca href=\"\/products\/weld-powder-natural-dye\"\u003eweld\u003c\/a\u003e or \u003ca href=\"\/products\/pomegranate-peel-powder-dye\"\u003epomegranate\u003c\/a\u003e.\u003c\/li\u003e\n\u003cli\u003eDissolve the weighed iron in a cup of cold water, then add it to a pot or bucket of warm water (about 50 °C \/ 120 °F) with room for the fiber to move.\u003c\/li\u003e\n\u003cli\u003eAdd the wet, dyed fiber and keep it moving. Colors change within minutes. Lift it out as soon as you like the shade; do not leave fiber in iron for more than about 30 minutes.\u003c\/li\u003e\n\u003cli\u003eRinse well, then wash with a pH-neutral soap.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003ch2\u003eTips and safety\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eKeep iron separate.\u003c\/strong\u003e Use a dedicated pot, spoon and bucket for iron. Even small traces left in equipment will dull later dye baths.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStart small.\u003c\/strong\u003e You can always dip again, but you cannot remove iron once the color has shifted.\u003c\/li\u003e\n\u003cli\u003eWear gloves and a dust mask when weighing, avoid breathing steam, and cover work surfaces: iron stains wood and skin.\u003c\/li\u003e\n\u003cli\u003eKeep out of reach of children. Iron is harmful if swallowed. Store sealed in a dry place.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eSee it in action:\u003c\/strong\u003e \u003ca href=\"\/blogs\/news\/how-to-madder-dyeing-purples-and-mauves\"\u003emadder purples and mauves with iron\u003c\/a\u003e · \u003ca href=\"\/blogs\/news\/how-to-make-oakgall-ink\"\u003eiron gall ink\u003c\/a\u003e · \u003ca href=\"\/blogs\/news\/weld-powder-dye-recipes\"\u003eweld olive greens\u003c\/a\u003e\u003c\/p\u003e\n\u003ch2\u003eFrequently asked questions\u003c\/h2\u003e\n\u003ch3\u003eWhat does iron do in natural dyeing?\u003c\/h3\u003e\n\u003cp\u003eIron darkens and cools colors. It turns yellows olive, reds purple and tannins gray to black, and it improves light fastness.\u003c\/p\u003e\n\u003ch3\u003eCan I use iron on wool?\u003c\/h3\u003e\n\u003cp\u003eYes, but use 1% WOF or less and keep the temperature low. Too much iron makes wool and silk harsh and brittle.\u003c\/p\u003e\n\u003ch3\u003eHow long does 50 g of iron last?\u003c\/h3\u003e\n\u003cp\u003eA long time. At 1% WOF, 50 g of iron is enough to modify about 5 kg of fiber.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eRead the guide:\u003c\/strong\u003e \u003ca href=\"\/blogs\/news\/iron-mordant-ferrous-sulfate-guide\"\u003eIron mordant guide\u003c\/a\u003e\u003c\/p\u003e\n\u003cp\u003eWork out exact grams for your fabric with our free \u003ca href=\"\/pages\/natural-dye-wof-calculator\"\u003enatural dye calculator and WOF chart\u003c\/a\u003e.\u003c\/p\u003e\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"What does iron do in natural dyeing?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Iron darkens and cools colors. It turns yellows olive, reds purple and tannins gray to black, and it improves light fastness.\"}},{\"@type\":\"Question\",\"name\":\"Can I use iron on wool?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes, but use 1% WOF or less and keep the temperature low. Too much iron makes wool and silk harsh and brittle.\"}},{\"@type\":\"Question\",\"name\":\"How long does 50 g of iron last?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"A long time. At 1% WOF, 50 g of iron is enough to modify about 5 kg of fiber.\"}}]}\u003c\/script\u003e","brand":"themazi","offers":[{"title":"50 gr","offer_id":37076109983901,"sku":"IRON50","price":5.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0402\/1990\/2109\/products\/IMG_6402.jpg?v=1635021433"},{"product_id":"aluminium-potassium-sulphate-mordant-modifiers","title":"Alum Mordant","description":"\u003cp\u003e\u003cstrong\u003eAlum (potassium aluminium sulphate)\u003c\/strong\u003e is a classic mordant used in natural dyeing to help dyes bond to fibers and improve wash and light fastness. It suits most natural fibers and is especially popular for bright, clear colors.\u003c\/p\u003e\n\u003ch3\u003eBest for\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eProtein fibers:\u003c\/strong\u003e wool, silk\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCellulose fibers:\u003c\/strong\u003e cotton, linen, hemp, bamboo (tannin pre-treatment recommended)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eHow to use (by weight of fiber, WOF)\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eWool and silk:\u003c\/strong\u003e use 10-15% WOF alum. Dissolve fully in hot water, add to a mordant bath, then add pre-wetted fiber and hold warm for 1-2 hours (or soak longer for convenience).\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCotton and linen:\u003c\/strong\u003e first treat with tannin (8-10% WOF), then mordant with alum (15% WOF) and \u003ca href=\"\/products\/soda-ash-sodium-carbonate\"\u003esoda ash\u003c\/a\u003e (2% WOF) in a warm bath.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003ePowder or crystals\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePowder:\u003c\/strong\u003e dissolves faster and is ideal for quick prep or small batches.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCrystals:\u003c\/strong\u003e easy to handle and measure for larger batches.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eResults are the same when measured by weight.\u003c\/p\u003e\n\u003ch3\u003eNotes\u003c\/h3\u003e\n\u003cp\u003eResults vary with fiber type, dye type and water chemistry. Store dry and tightly closed.\u003c\/p\u003e\n\u003ch3\u003eLearn more\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca href=\"https:\/\/themazi.com\/blogs\/news\/how-to-prepare-fiber-fabric-for-natural-dyeing\"\u003eHow to prepare fiber and fabric for natural dyeing\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/products\/oak-gallnut-powder-green\"\u003eRecommended tannins for cellulose: green oak gall powder\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eWork out exact grams for your fabric with our free \u003ca href=\"\/pages\/natural-dye-wof-calculator\"\u003enatural dye calculator and WOF chart\u003c\/a\u003e.\u003c\/p\u003e","brand":"themazi","offers":[{"title":"Crystals \/ 100 g (3.5 oz)","offer_id":44226202075370,"sku":"","price":7.9,"currency_code":"USD","in_stock":true},{"title":"Crystals \/ 400 g (14.1 oz)","offer_id":43365180244202,"sku":"","price":18.9,"currency_code":"USD","in_stock":true},{"title":"Crystals \/ 1 kg (2.2 lb)","offer_id":44226202108138,"sku":"","price":28.9,"currency_code":"USD","in_stock":true},{"title":"Powder \/ 100 g (3.5 oz)","offer_id":45856244138218,"sku":null,"price":8.9,"currency_code":"USD","in_stock":true},{"title":"Powder \/ 400 g (14.1 oz)","offer_id":45856244170986,"sku":null,"price":19.9,"currency_code":"USD","in_stock":true},{"title":"Powder \/ 1 kg (2.2 lb)","offer_id":45856244203754,"sku":null,"price":29.9,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0402\/1990\/2109\/files\/themazi-alum-potassium-aluminium-sulphate-mordant-dye-assistant.jpg?v=1771528782"},{"product_id":"cellulose-mordant-kit-cotton-linen","title":"Cellulose Mordant Studio Kit","description":"\u003cdiv\u003e\u003cspan\u003eA complete mordanting kit for cotton, linen and other cellulose fibers.\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003eDesigned around our recommended mordanting ratios, this kit contains the materials needed to prepare up to approximately 4 kg (8.8 lb) of cellulose fiber for natural dyeing.\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003eINCLUDED:\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e• 400 g White Oak Gall Powder (Tannin)\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e• 600 g Alum Powder\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e• 100 g Sodium Carbonate (Soda Ash)\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003eWHY THIS KIT:\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e• Correctly balanced quantities — no guesswork\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e• Suitable for cotton, linen, hemp and other cellulose fibers\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e• Enough materials for up to approximately 4 kg (8.8 lb) of fiber\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e• Better value than purchasing the components separately\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e• Ideal for natural dyers, textile studios and small-batch production\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003eHOW IT WORKS:\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e1. Pre-treat the cellulose fiber with White Oak Gall tannin.\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e2. Mordant with alum.\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e3. Use soda ash as directed in the mordanting process.\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e4. Continue with your chosen natural dye.\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cspan\u003eThe exact amount of fiber that can be treated may vary depending on the recipe, fiber type and process used.\u003c\/span\u003e\u003c\/div\u003e\n\u003cp\u003eWork out exact grams for your fabric with our free \u003ca href=\"\/pages\/natural-dye-wof-calculator\"\u003enatural dye calculator and WOF chart\u003c\/a\u003e.\u003c\/p\u003e","brand":"themazi","offers":[{"title":"Default Title","offer_id":46226899435754,"sku":null,"price":72.9,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0402\/1990\/2109\/files\/THEMAZ_Cellulose_Mordant_Studio_Kit_for_cotton_linen_and_other_cellulose_fibers.webp?v=1788363056"}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0402\/1990\/2109\/collections\/alum-crystals-potassium-aluminium-sulphate-bowl-themazi.jpg?v=1792531451","url":"https:\/\/themazi.com\/collections\/alum-iron-mordants.oembed","provider":"themazi","version":"1.0","type":"link"}