A Gentle Introduction to Dyeing with Kitchen Scraps
If you’ve ever sorted through onion skins before cooking or carved an avocado and wondered if the pit could be useful, you are already halfway to creating natural dyes. The idea that natural dyeing requires a laboratory of powders and precise measurements is a common misconception. Many colour-giving plants contain enough tannin to bind dye to fabric on their own, and even those that need a little help can be partnered with a single, widely available mineral: alum.
This guide focuses on two of the most accessible kitchen-waste dyes: yellow and orange from onion skins, and pink from avocado pits. Both produce clear, lightfast colours on natural fibres, and both are forgiving enough for a first attempt. No special equipment is needed beyond a large pot, a strainer, and a few pieces of fabric.
Photo by Kern Morris on Unsplash.
What You’ll Need
Before you start, gather the following:
- Onion skins: You can use the dry, papery outer layers from yellow or red onions. Red onion skins tend toward a deeper russet orange, yellow onions yield a clear golden yellow. Collect them over time in a paper bag; they keep for months.
- Avocado pits: Rinse them clean of any flesh, then let them dry. You need roughly 6–8 pits per litre of dye liquid. You can also use the skins, which add a little extra tannin and deepen the pink.
- Alum (potassium aluminium sulphate): This is the safest and most common mordant for natural dyes at home. It is sold in craft stores or online as a white powder. You’ll need about 10–15% of the dry weight of your fabric.
- Fabric: Choose natural fibres only – cotton, linen, silk, or wool. Synthetic fibres will not absorb the dye. For consistent results, use prepared-for-dyeing fabric (scoured and without finishes). Old white cotton T-shirts, silk scarves, or wool yarn all work well.
- Large stainless steel or enamel pot: Do not use aluminium or iron, as they can react with the dye and muddy the colour.
- Water: Soft water is best; if your tap water is very hard, use filtered or distilled water to avoid dull colours.
Preparing the Fabric: Scouring and Mordanting
Before dyeing, fabric must be clean of any oils, waxes, or finishing agents. This is called scouring.
Scouring
Wash your fabric in hot water with a small amount of mild, pH-neutral detergent. Rinse well. For protein fibres (silk and wool), use a gentle wool wash and avoid sudden temperature changes that could felt the fibres.
Mordanting with Alum
Mordanting helps the dye molecules bind to the fabric, making the colour more permanent. Alum is non-toxic and leaves the fabric feeling soft.
- Weigh your dry fabric. For every 100g of fabric, prepare 10–15g of alum (about 2–3 teaspoons). Dissolve the alum in a bowl of very hot water, then add it to a pot filled with enough cool water to fully submerge the fabric.
- Add the wet fabric (after scouring) to the alum solution. Slowly bring the pot to a gentle simmer (not a rolling boil) and hold it there for 60 minutes for cotton or linen, or 45 minutes for silk or wool. Stir occasionally.
- Turn off the heat and let the fabric cool in the mordant bath. Then remove it, squeeze out excess liquid gently (do not wring), and proceed to the dye bath while the fabric is still wet. Do not rinse out the alum – it is part of the dyeing process.
Photo by Anna Evans on Unsplash.
Making the Dye Bath
Onion Skin Dye
Place a generous handful of onion skins in your pot – about enough to fill two cups loosely packed. Add water to cover them by a few inches. Bring to a simmer, then reduce heat and let it steep for 30–60 minutes. The longer it simmers, the deeper the colour. Strain out the skins and discard them. The liquid will be a rich amber.
Avocado Pit Dye
Crush or chop the avocado pits into small pieces (a hammer wrapped in a cloth works; be careful). This exposes more surface area for colour release. Place the pieces in the pot, cover with water, and simmer for at least 1.5 hours. The liquid will turn a pale beige at first, then deepen to a soft pink. Longer simmering (2–3 hours) yields a stronger colour. Strain out the pits before dyeing.
Dyeing the Fabric
Transfer your wet, mordanted fabric into the strained dye bath. Use enough liquid so the fabric moves freely. Slowly bring the pot to a gentle simmer (around 80–90°C). Keep it at this temperature for one hour, stirring gently every 10 minutes to ensure even coverage.
After an hour, turn off the heat and leave the fabric in the dye bath until the liquid cools completely. This allows the colour to fully bond. The fabric will look darker when wet; it will lighten as it dries.
Remove the fabric, rinse it under cool running water until the water runs clear. Wash it with a mild soap (pH-neutral), then hang it to dry out of direct sunlight.
Photo by Steve A Johnson on Unsplash.
Setting and Caring for the Colour
Natural dyes are beautiful but require a little care. To set the colour further, some dyers add a vinegar rinse (1 part white vinegar to 4 parts water) after dyeing, but this is not essential if you have mordanted properly. For wool and silk, vinegar can help neutralise any residual alkalinity.
Wash naturally dyed items by hand in cool water with a gentle soap, and avoid prolonged direct sunlight, which can fade even the best-fixed colours. Store them away from bright light when not in use.
Common Mistakes and How to Avoid Them
- Using too much fabric in the bath: The dye liquid should be several times the weight of the fabric. Overcrowding leads to uneven, pale results.
- Boiling the dye bath: A hard boil can damage delicate fibres (especially silk and wool) and cause the dye to break down. Keep it at a bare simmer.
- Skipping the mordant: While some plants like avocado pits contain enough tannin to act as a natural mordant, adding alum gives longer-lasting and more predictable colour. It is worth the small extra step.
- Not straining the dye bath: Small floating bits of onion skins or avocado can stick to the fabric and create blotchy spots. Strain carefully.
- Expecting neon or pastel shades: Natural dyes produce muted, earthy colours. The beauty is in their subtle variation. If you want a specific shade, test on a scrap first.
Experimenting Further
Once you feel comfortable with these two dyes, you can combine them: dye fabric first in onion skins, then over-dye with avocado pits for a peachy orange. You can also try adjusting the pH – a splash of lemon juice will shift avocado pink toward a cooler rose, while a pinch of baking soda will make it more salmon. Always test on a small sample.
Natural dyeing is a slow, meditative process. There is no rush. The colours you produce are a record of the seasons and the scraps you saved, and that is part of their quiet charm.