I have received a lot of emails the last couple of weeks, asking about how to mordant linen and cotton fabric. After repeatedly answering the same question over and over again, I thought why not post it on the blog?
There are several different methods of mordanting cellulose fibres, but I found the following technique the most practical. Many other recipes require Alum acetate, which I personally avoid using. I like to use what I have at hand and this recipe works a treat. Keep in mind that you will need time. This can be done within 4-5 hours or over a couple of days if you choose the non heated version.
You can find a tip section at the end of this article - a shorter version of the text below.
There are several different tannin rich plants that can be used, each slightly different from the next. Tannin will always leave a slightly yellow buttery colour behind. Tara and Oak Gall less so than Myrobalan. If you are planning on light colours, I would leave out the Myrobalan. Another little trick - if you add your fabric to a 2-5% iron after bath, your fabric will turn grey to dark grey/black once it has been mordanted with a tannin rich dye. The richer in tannin the darker the results. If that is the colour you require - leave out the Alum/Soda Ash Step. Alum brightens dyes, which might not be what you are looking for when going for black.
Before we start, if you want to dye your fabric with Indigo - no mordanting is required. You only need to scour your fabric.
Double layered organic cotton dyed in an Organic Indigo Vat
Before (left) and after (right) scouring single layered organic cotton
(Please note that some fabrics come already scoured in which case you can skip this step.)
A pot big enough to hold your fabric
1 tsp of Soda Ash (or 1% of w.o.f.)
1/2 -1 tsp of organic washing up liquid
- Heat resistant rubber gloves
Mordanting cellulose fabrics succesfully.
A 2 step process, please read through the entire instructions first.
1.Fill a plastic or stainless steel vessel with hot water (40-50 d. Celcius/100-120F) to a 30:1 ratio (water:fabric)
2. Add tannin and stir until dissolved or evenly distributed
3. Add fabric, immerse fully for 1-2 hours. The bath will cool down, which is totally fine. Stir occasionally.
4. Use rubber gloves when removing fabric, squeeze fabric. Rinse very lightly or better spin it out using a centrifugal spinner or washing machine. Tannin is bound to the fibre only by affinity and can be removed if rinsed aggressively.
5. Save mordant for future use.
6. Don't let it dry before moving on to Step 2.
Alum 12% (w.o.f.) Dissolved in enough boiling water, cool.
Soda Ash 1.5% (w.o.f.) Dissolve in enough boiling water, cool.
1. Combine the two solutions while stirring. It will bubble, so make sure your vessel is big enough.
2. Bubbles will subside quickly and you should be left with a clear liquid. Add additional hot water as described above (Steps 3 and 5 from above).
3. Rinse the textile well, to make sure any unattached mordant is rinsed off.
4. The textile may be dyed immediately or dried for future use.
*Too hot and the tannin will oxidize, which is fine, if you want a potentially darker colour. For overdyeing, it is best to keep the colour as light as possible.
** You can also use cold water instead of hot, but it will require a 12h or overnight soak
***Any tannin can be used with this recipe, but for lighter results use Oak Gall or Tara.