Onion skins are one of my favorite natural dyes, with colors ranging from yellow with alum mordant to deep rust and brown (with iron). I usually just mix them all in one dye bath… I’ve been curious whether red and yellow onion skins give different colors when dyeing silk, so I decided to do a test. I separated, then weighed out equal amounts of red and yellow onion skins, then simmered them separately in stainless steel pans for about an hour and let the dye cool and sit overnight.
I added some squares of silk into each pot: no mordant, alum pre-mordant, iron pre-mordant plus some cotton. The red onion skins gave a slightly darker, more muted color. I was surprised that pre-mordanting with alum didn’t make a difference in the color, at least this time. Simmering it longer, about 15 minutes, made more of a difference in color. The silk squares pre-mordanted with iron turned a very dark brown.
- So far I still like the color I’ve gotten using a mix of red and yellow onion the best.
- More onion skins to fabric and longer simmering times gave more intense colors.
- Pre-mordanting the silk with Alum had little, if any, effect. (I don’t quite believe this one, so I’ll keep throwing test squares into future onion skin pots.)
- Just a bit of iron mordant gives a very dark brown.
Here are a couple of examples of my eco printed scarves using onion skin dye.