To be safe, designate a pot specifically for dyeing projects, and use gloves to protect your skin. If you're dyeing in the kitchen, work in the sink and avoid surfaces used for preparing foods. Although natural-dyeing books from the '60s, '70s and '80s are plentiful, experts warn that books from that period often recommend using toxic substances like chrome, copper or even lead as mordants.
"You just don't want to be inhaling that kind of thing," said Duerr.
As a rule, leaves should be chopped, the more finely the more colorful the pigment; berries should be mashed with a potato masher; and bark and roots can be shredded or ground.
Wrapping the natural materials in muslin or putting them in some old pantyhose makes projects neater and easier.
If boiling berries, sometimes the longer they are boiled, the lighter the pigment, so for darker shades either add more berries or let the water cool slowly.
But onion skins are the classic home dyeing project for beginners.
"We do onion skins with kids here at the botanic garden. The yellow color is fantastic," said Uyterhoeven. "People can go to farmers' markets or grocery stores and get loads of onion skins, because people usually just throw them out."
First, peel the papery red or yellow skins from lots of onions, ideally enough to fill your biggest pot. Aluminum pots make for a brighter color dye, but any pot will work. Cover the skins with water and bring to a boil. Then simmer for at least an hour.
Next, in a separate pot, soak the natural fabric or yarn you'd like to dye in hot water for at least 15 minutes. Wet fabric absorbs dye much better than dry fabric does. For tie-dyed fabrics, just fold and then wrap rubber bands around the still-dry fabric first.