How long to boil eco-print bundles

When I first started eco-printing, I boiled my bundles for 3 hours. I got good results, so I kept doing this. But one day I noticed that after a short amount of boiling the leaves had already produced a lot of beautiful colour.

So I decided to take a more systematic approach to working out the optimal length of boiling. I made up a batch of small bundles using leaves from 3 different eucalyptus varieties on pieces of the same pre-mordanted cotton. I set them to boil, then removed them at 15 minute intervals.

I was suprised to see that there wasn’t much difference between the bundle that had been boiled for just 15 minutes (left), and the very last one which was left in for 1 hour and 45 minutes (right).

Comparing different boiling times for eco-print bundles

The colour of the leaves on the top sides did shift from brown to blue with longer boiling times, but the centre green and botton brown leaf prints didn’t really vary. The blue band on the right side print is from the piece of dowel that the bundles were wrapped around. This band got progressively darker and bled more the longer that each sample was boiled for, because wood has its own tannins.

Even though much of the dye has already emerged after 15 minutes, I do cook my bundles for longer, to ensure that the maximum amount of colour is transferred to the fabric and to really give it time to set. I find that about 1 hour is a good length of time when eco-printing on cotton. It’s enough time to get strong prints, while being mindful of energy use.

A comparision of cooking times for cotton eco-print bundles

14 thoughts on “How long to boil eco-print bundles”

    1. Sorry Peggy, I only ever boil my bundle because I find it a simpler process and I like the results I get. But you could set up a little experiment yourself.

    1. Hi Sharon, pre-mordanted means fabric that has previously been prepared with a mordant (metallic salt), which helps the natural dyes to bond with it. Sometimes mordants are put in the pot with natural dyes, but for eco-printing you generally need to prepare it with a mordant in advance.

  1. I will be doing eco printing on silk. Do I need to pre-mordant it? What is metallic salt? Will aluminum sulphate do?

    1. I rarely use silk myself, but yes for most leaves, you will get better results from mordanted silk – eucalyptus is one exception. Alum is a common mordant for silk, do a Google search to find recipes and ratios.

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  3. Hi I tried this several times… But I didn’t get visible results… I used rust water dipped leaves,flowers and as mordant I used baking soda… I wrapped it with an aluminum foil as barrier layer. Still didn’t work. Can you please let me know what goes wrong here?

    1. Hello. There’s lots of variables, so it can be hard to pinpoint the problem. I’d suggest trying again without the baking soda – it’s not actually a mordant, and the iron should be enough for the plant dyes to bind anyway. It could also be a problem with the leaves you used – look around at what other eco-printers are getting good results with. Rose, eucalyptus, maple and geranium are nice starting points when working with an iron mordant. And make sure your rust water is strong enough. I personally use iron plus vinegar to make my mordants, not water. Once the colour has darkened, it’s good to go.

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