A few weeks ago my Aunty (the very creative and inspiring hand weaver, spinner and textile designer Madeleine Jude) very kindly spent the day giving me a little glimpse into the alchemy of indigo dying. Working with natural dyes is quite daunting – I’m so glad I had someone to show me rather than trying to figure it out for myself from a book. Today I’m sharing some photos of the dye making process along with the recipe we used for our indigo vat. I chose to dye a stack of muslin squares which I folded using some simple shibori folding techniques which I learnt mostly from YouTube.

We based our dye vat on a recipe from Colours from Nature – A Dyer’s Handbook by Jenny Dean. The original recipe calls for ‘colour run remover’ to eliminate oxygen from the water but modern colour run removers don’t work in the same way so we used sodium hydrosulphite (hydros) instead. The quantities below made enough dye to handle 8 muslin squares, a length of cotton that had been knocking about in my stash for years and about 40g of yarn with plenty left to spare.

Before we delve into the dye recipe, here are a few interesting things about indigo!

• Indigo is the only source of true blue dye in nature but lots of different plants produce indigo.
• In order for the dye to adhere to the fibre it needs to be in a form called ‘indigo white’ (which is actually a greenish yellow colour) rather than the thick, gloopy blue liquid that you imagine. Indigo can only exist in the form of indigo white when no oxygen is present (hence the hydros). This means that when the fabric or yarn first emerges from the dye vat it will be a funny colour but as the oxygen gets to it it will transform before your eyes into deep and delicious indigo blue.
• Once you have finished dying your fabric, allow it to dry naturally for a couple of days before washing gently. After this your dye should be all set.
• You’ll need to make sure all fabric or yarn has been washed thoroughly to remove any natural oils that might interfere with the fibre’s ability to absorb the dye. You’ll also need to make sure the fabric or yarn has been soaked in water before dipping it into the dye – but squeeze it out well to make sure it doesn’t dilute the dye vat or drip into it (introducing dreaded oxygen).
• Medium have published an interesting article about the evolution of Indigo dye which looks at it’s origins in India, Africa and China through to the synthetic indigo dyes more readily available today.

Materials and equipment:

• Ideally, a large electric water heating canister (something along these lines). Failing that, a very large pan and a stove top.
• Indigo powder (Madeleine buys her’s from P&M Woolcraft which you can order online).
• Sodium Hydrosulphite
• Washing soda
• Litmus test strips
• Measuring spoons
• Kilner jar (or similar) to mix up the indigo powder
• Thermometer
• Rubber gloves
• Wooden spoon with a long handle
• Fabric or yarn to dye
• Bucket of clean, cold water ready to dunk your fabric or yarn in after it comes out of the dye vat.
• A washing line to hang it all out to dry.

Recipe:

1. Dissolve 4.5 tsp washing soda in 3-6 tbsp boiling water and allow to cool slightly. Then add 6 level tsp indigo powder to this solution and mix very well into a smooth paste (this could take up to 10 minutes) adding more water if necessary. We used a Kilner jar which I would recommend as you can seal it up tightly and give it a good shake. Make sure no gritty particles remain then leave to stand until you’re ready to use it (or at least 15 minutes).
2. Put enough water to make the vat into a stainless steel dye pot (we used around 12 litres) and heat to 50C/120F. This is about as hot as your hand can take. Make sure the temperature doesn’t exceed 60C/140F.
3. Add approximately 25 to 30g/1oz of hydros and stir very gently. Leave for a minute or two, then very slowly and carefully stir in the indigo paste solution, making sure not to create any air bubbles as you do so. Remember, the hydros is there to remove the oxygen from the water so from this point on it’s all about not agitating the liquid or letting anything drip into it that could re-introduce oxygen and stop the dye working.
4. Put the lid on the pot and, keeping the temperature constant, leave the vat to stand for 30-45 minutes or until the liquid below the surface has changed from blue to greenish yellow in colour. (The surface may still appear blue because it is in contact with the oxygen). If after 45 minutes the liquid still appears blue, add a little more hydros  and leave for a further 5 – 10 minutes. We added an additional 3 tsp of hydros before the dye was ready, using litmus test strips to check when the dye was sufficiently alkali (it should be somewhere between 9 and 10). You can immediately tell once the dye is ready as it suddenly clings to the wooden spoon, coating it in thick, deep colour (and ruining it forever).
5. Gently add the wetted yarn or fabric, remembering to squeeze out any excess water first. Do not put more material into the vat than will lie easily below the surface, as any sections above the surface will become blotchy. Each vat will be different and require a different amount of time – we found that 10 seconds was perfect but some recipes suggest submerging the fibres for up to 20 minutes! I recommend starting with a shorter dip and re-dipping if necessary.
6. Remove the materials very gently, making sure they do not drip into the vat, then immerse them in a bucket of cold water. This is particularly important if there are any grainy particles of indigo dye powder still undissolved as these can cause blotches in your finished fabric but the bucket of water should lift them off before they have the chance to do any damage.