Easy Eco Printing with Sumac

It’s tough to drive down the roads and not look at all the sumac! The perfect time is right now! Eco Printing with Sumac; easy but great for some wonderful reliable botanical prints.

Sensational Sumac!

Whether it’s in spring, summer or fall, sumac is one of my favourite eco printers! Here in Canada Staghorn Sumac grows at a proliferate rate along roadsides, parks and forest edges. It starts green but has some of the best colours in the fall. Staghorn Sumac should not be confused with poisonous sumac; Poison sumac has clusters of white or light-green berries that sag downward on its branches, while the red berries of harmless sumac sit upright.

As you know, I often collect leaves and dry them for later use. Sumac tends to be a bit more difficult to dry and store; instead I ended up with a lot of dried sumac that is stored like loose-leaf tea. Sumac leaves print a reliable lovely purplish grey colour from the underside so I know they have many tannins.

For this rich brew I used 2 cups of dried sumac leaves steeped in boiling water for 20 minutes or longer (added to 2.5 litres water). Not all natural dye stuff can take high heat or a long boiling so I’d rather use time to bring out the tannins.

Historically, the tannins of sumac were used to treat the collagen in animal skins to make them into leather, hence the term tanning leather. This is an important method to allow the skins to have a long life. Many of the principles of eco printing were discovered in some form many centuries ago.

Simple Eco Print Method:

For this experimentation I am using vintage cotton muslin that has been well scoured. I tend to like ‘older’ cottons rather than newer ones as I find they take print better. Perhaps there are additives or coatings that seem to inhibit the take-up of colour in modern cotton. I am also using Iron (Ferrous Sulfate) as a mordant for the cotton. (1 teaspoon Ferrous Sulphate to 5 litres water)

This is the colour of the ‘Sumac tea’, a golden reddish liquid (2 cups of dried sumac leaves + 2.5 litres water) When calculating how much matter to use; ‘weight of fibre’ (WOF) is relative to amount of substance used. As an artist I like to be a bit more free-form instead of calculating! Experimentation is key along with much note taking. But do understand, the plant material, the species, the climate, water quality all play some importance of what result you achieve, but that also allows the unexpected magic!

The cotton fabric is soaked in the Sumac tannin tea for 20 minutes, squeezed and agitated.

The base of this eco print is also the cotton fabric dipped into a bucket of ‘iron water’ (1 teaspoon Ferrous Sulphate to 5 litres water). The iron will react with the tannins so prints will be reliable. How the prints will look depends on the foliage used; much like the Resist method of eco printing. I have used ferns here since they do not typically have much tannin but do provide great shapes as a resist (the silhouette of the leaf shapes). You are welcome to use any plant material layered on the base fabric, tannin rich or not…

Can you guess what the flower-shapes are?!

Double Layer Eco Printing with Sumac

After the other cotton fabric is soaked in the Sumac tannin and rung out well (be careful to not contaminate the iron solution with the sumac tannin solution) it is placed over the iron dipped cotton with plant material placed. To prevent some of the prints bleeding through the layers I use a ‘barrier’ (a layer of up-cycled plastic that gets re-used many many times). There are various barriers that can be used including paper and other fabric.

Roll the layers are tightly as possible to produce the clearest prints in the fabric. Any wrinkles should also be pulled flat. Careful planning for width of fabrics and rolling dowel helps make it easier. I use old wooden curtain rods as my dowels but some even use pipes.

Once rolled it is well tied with the string (that again is used many many times) using my quick-tie method. Any way of making it quicker and easier on the fingers is well received! The tied bundle is also placed in a up-cycled plastic bag (from grocery fruits) and an elastic keeps it closed.

Processing the ‘Bundle’ of sumac joy

To make my life easier and also save energy I use the microwave to process my eco prints! I know it does not sound as glamorous as standing around a cauldron out in the country but it is very convenient for me! I can bundle and process 8 bundles between doing laundry – no bundle-sitting needed!

Use small bursts of 1-2 minutes depending on the bundle size. The bundle will get hot but should not start ‘blowing up’. You can use a laser thermometer or I use my hand; if it almost ‘too hot to handle’, I pop it under a thick layering of blankets/towels to hold the heat. I go tend to other things and the heat holds well, especially if there are a few bundles ‘insulating’ together. I’m amazed at how long the heat lasts!

I’ll often go back later and give them another small burst of 1-2 minutes, then back to insulate. In my opinion it is much like the constant heat of a cooking vessel. Since it is encapsulated it also keeps the fumes from escaping. No one notices a smell. I often like to leave them insulating to the next morning. It’s a nice ‘gift’ to look forward to the next day!

The Reveal:

I never tire of the fun of opening the bundles! Oh, the anticipation and amazement each time! Yes, they do look darker than when they dry but it all depends on the amounts of the tannin and iron combination! I can often already see it reacting in the bottom of the sink… (often learn so much from cleaning up)

If you notice the silhouette (top) is the ‘tannin dipped’ fabric and the other (lower) is the one that was iron dipped. Each one has its’ unique appeal.

To wash I use a ph neutral soap like blue Dawn and wash rigorously by hand, rinse well and line dry. I hate to use the washing machine for cottons as I find that the rub-factor from aggressive machines can wear out areas at the folded parts. It’s similar to what happens at jeans on the seams etc.

This ‘sandwich’ method will give 2 mirror pieces that can give some nice design possibilities.

Myrobalan (another tannin-rich tea) can also give this effect. As you may notice the colours are often a rich purple-like grey colour dependant on the amounts of tannin reacting with the iron (iron sulphate solution)

…But then again, eco print as you like! Sumac cane be wonderful in many methods of this art form; even just using an iron blanket! Happy printing and experimenting!

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  1. Barb, since sumac is in abundance right now, can you use fresh sumac leaves instead of dried to make the dye?

  2. Do you know anyone that has dried sumac? I cannot find it growing anywhere in San Francisco. I even visited the botanical gardens to ask. They said they tried to grow it and it didn’t.

  3. Hi Barb – how cool!!
    Now being that it is summer right now do you feel maybe the sun may heat up the rolls enough that a microwave is not required?

  4. Hi, can you give the latin name of the Myrabolan you use? I see different trees referred to under that name.

  5. I’m finding your posts so interesting as I am new to eco-printing. I live in Namibia and am very limited to varieties of vegetation to use. I am able to get Sumac powder as a food spice… do you think this would work as the foilage does?
    Thank you so much for sharing all your methods!

    1. Hello! I bet there are a lot of types of leaves that you could try to experiment with. Eucalyptus? Pomegranate, Wild Olive (South African Olienhout) even leaves from roses (not petals) The sumac powder may give a colour dye but I do not have experience with it. Gather the leaves that you can and do some test prints, that’s the best way, or search out some local workshops… Good luck

  6. Thanks for this Barbara. I’m going to try dried sumac (herb). I notice that you use your plastic barrier on the inside whereas I’ve been using mine on the outside but I think I will switch as your plastic looks soft and mine is quite hard from being on the outside and getting the brunt of the heat. Thanks again for posts.

  7. Hello, I would like to know how to safely dispose of the ferrous sulfate dissolved in the water, as I found out it is toxic (not just) for aquatic life and should not be just poured away in the garden or so…can you help me? Thank you.