Natural Dyeing: Color Fabric with Food and Foraged Plants

First, scour your fabric — wash it in hot water with a small amount of dish soap to remove any finishes, oils, or sizing that would block dye uptake. Rinse thoroughly and keep the fabric wet; dry fiber going into a mordant bath can cause uneven uptake. Weigh your dry fiber before wetting it so you know your WOF (weight of fiber) for calculating mordant amounts. For alum mordant on wool: dissolve 15g of alum (potassium aluminum sulfate) per 100g of fiber in a cup of hot water, then add it to your pot filled with enough warm water to let the fabric move freely. Add your wet fiber, heat slowly to around 80°C (175°F) over 30–40 minutes, and hold at that temperature for another 45 minutes. Stir gently every 10 minutes — too much agitation felts wool. Lift the fiber out, gently squeeze (don't wring), and either move it directly into your dye bath or set it aside wrapped in plastic if you're not dyeing immediately. A mordanted fiber held for a day or two stays ready. Don't rinse out the mordant — that's the whole point. The alum is now bonded to the fiber, waiting for the dye molecules to attach to it.

For plant-based dyes, extraction is simple: put your dye material in the pot, cover generously with water, and simmer (not boil) for 45–60 minutes. Onion skins, avocado pits and skins, dried marigold petals, and black walnut hulls all extract well this way. Use a rough ratio of equal weights of dye material to fiber — 100g of onion skins for 100g of fiber gives a strong, saturated color. After simmering, strain out all plant material using a cheesecloth or fine mesh strainer. What's left in the pot is your dye bath — a liquid that looks nothing like the final color on fiber. Onion skin liquid is a dark brown-orange; avocado pit liquid is a murky pink-brown. The colors transform and brighten dramatically once they bond with mordanted fiber, so don't judge the bath by how it looks at this stage. For fresh plant material like nettles, bracken fern, or black-eyed Susan flowers, the ratio shifts — use 2–3 times the weight of fiber in plant material to compensate for higher water content. Dried materials are more concentrated. You can also freeze dye baths to use later, or do successive dye baths with the same liquid for lighter, more exhausted color on additional skeins.

Warm your strained dye bath back to about 70°C (160°F) and submerge your pre-wetted, mordanted fiber. The fiber must go in wet — dry fiber entering a dye bath creates hard edges and blotchiness. Gently push it under the surface so it's fully covered, then heat slowly to 80°C over 20–30 minutes. Stir gently and regularly, especially during the first 15 minutes when most of the color uptake happens. Hold the temperature at 80°C for 45–60 minutes, stirring occasionally. Watch as the bath exhausts — the liquid will gradually go from rich and opaque to clearer as the dye bonds to the fiber. A fully exhausted bath means excellent dye uptake and minimal rinsing needed. If the bath is still deeply colored after an hour, your fiber has absorbed what it can; don't leave it longer hoping for more color. Optional: add an iron modifier in the last 10 minutes. Dissolve a small pinch of ferrous sulfate (about 2g per 100g fiber) in hot water and stir it into the bath. The color will shift and deepen almost immediately — greens go olive, yellows go green, oranges go brown. Iron is a powerful modifier, so use sparingly. Remove the fiber, let the bath cool slightly, then proceed to rinsing.

Rinse your dyed fiber in water that's close to the dye bath temperature — a dramatic temperature shift can shock wool fibers and cause felting. Start with warm water, then cool gradually through successive rinses until the water runs clear. Add a small splash of white vinegar to one of the rinses for protein fibers; it helps set the color and restores the natural pH of wool. Gently squeeze (never wring or twist) the excess water out and lay the fiber flat on a towel to roll up and press, or hang it loosely in the shade to dry. Direct sunlight will bleach and fade many natural dyes even as they're drying — be especially careful with indigo, weld, and madder. Let the fiber dry completely before assessing the color; wet fiber always looks darker and more saturated than the finished result. For the first few washes of a naturally dyed garment or yarn, wash separately in cool water with a small amount of gentle wool wash or pH-neutral soap. Some residual dye will release in early washes — this is normal and doesn't mean the color will continue to fade. After two or three washes, most well-mordanted natural dyes are stable and can be washed with other items.