What to expect
Onion skins are a popular beginner natural dye because they are easy to collect and often give warm yellows, oranges and browns. Cotton, though, is a plant fiber, and plant fibers generally hold natural dyes less readily than wool or silk. For that reason, most guides recommend preparing cotton with a scour and a mordant. Results vary with the onions, water, fabric and method, so treat colors as unpredictable and test on a scrap first.
For general dyeing background, see our guide to dyeing fabric in a dye bath.
Materials
- Onion skins. Yellow and brown skins tend to give yellows, oranges and tans, while red onion skins can lean toward browns and greens, depending on the method.
- Cotton fabric or a garment, preferably white or light-colored and made of natural fibers
- A mordant suited to cotton, such as aluminum acetate (follow the supplier’s directions)
- Detergent and soda ash for scouring
- A stainless steel pot reserved for dyeing, not food
- A strainer, tongs or a stirring stick, and heat-safe gloves
A commonly cited rule of thumb is to use roughly the same weight of onion skins as the weight of fabric, though some people use more for deeper color.
Step 1: Scour the cotton
New cotton can carry oils, waxes or finishes that block dye. Scouring means washing it in hot water with detergent and soda ash, following the product directions, then rinsing. Hot water can also shrink untreated cotton, so read does cotton shrink in the wash before you start. Cotton prepared this way takes dye more evenly. Our guide to preparing and prewashing fabric covers the general principles.
Step 2: Mordant
A mordant helps the dye bind to the fiber and improves washfastness. Aluminum-based mordants are commonly used on cotton. Use the amounts and temperatures the supplier recommends, wear gloves and a mask for powders, and use dedicated equipment. Some people also use other treatments such as soy milk as a pre-treatment, but those are different methods with their own instructions.
Do you need a mordant? Some people dye without one and still get color, but the color may fade faster. For cotton, a mordant is generally advised.
Step 3: Make the dye bath
- Put the skins in the pot with enough water to cover the fabric later.
- Simmer gently (not a hard boil) for around an hour, or follow your recipe, until the water is richly colored.
- Strain out the skins.
Step 4: Dye the fabric
Add wet, mordanted fabric to the strained dye. Heat gently, stirring occasionally, and keep it in until it reaches a color you like. Leaving it longer or letting it cool in the bath can deepen the color. Rinse in cool water, then wash gently with a mild detergent and dry out of direct sun.
Modifiers
After dyeing, you can sometimes shift the color:
- Acid, such as lemon juice or vinegar, can brighten or shift toward yellow.
- Iron water (an iron solution) typically darkens colors toward olive or gray-brown. Handle with care and follow instructions.
- Alkaline additions such as soda ash can push colors toward red or orange.
Results vary, so test on a swatch. If you want green, expect that you may get olive or khaki tones rather than bright green.
Colorfastness and care
Natural dyes are generally less colorfast than commercial dyes. Onion skin colors can fade with sun and repeated washing. To help the color last, use a mordant, wash gently in cool water with mild detergent, and avoid long sun exposure.
Does food coloring dye cotton
Food coloring is made for food, and it generally does not bond to cotton in a lasting way. Colors tend to wash out. If you want durable color on cotton, a dye intended for cellulose fibers is the better route.
Other vegetables for dye
People have used avocado pits and skins, red cabbage, beets, turmeric and others, with differing results and lightfastness. Test and expect variation. Onion skin paper, by the way, is a different thing: a thin, lightweight paper, not a dye.
Frequently asked questions
How do I use onion skin as dye?
Simmer the skins in water, strain, then add prepared fabric to the liquid.
What vegetables can be used to dye fabric?
Onion skins, avocado, red cabbage and beets are commonly mentioned, though some fade quickly.
Is onion skin dye colorfast?
Moderately at best. Mordanting improves it, but expect some fading over time.
Is it safe?
Onion skins are food scraps, but mordants and additives are chemicals, so use dedicated equipment and follow safety directions.