Harvesting and processing indigo in the tropics – Sakhon Nakon, Thailand

It is late September now and we are back in Sakhon Nakon looking to learn more about indigo dyeing. This time our journey brings us to the Sericulture Department of the Phu Pan Study and Development Centre which we came across by accident while on our previous trip here. At the time we were unsure of what to look for exactly but began by poking our heads around in different places until we found a little house with walls of mosquito netting protected from critters by a water moat. Inside were trays upon trays of young silk worms munching away on mulberry leaves and in the middle of all this sat a wispy old man with a cautious liveliness and, as we came to learn, a good heart.

Everything fell into place when we told him that we were looking around for anything indigo related, at which point he smiled and pointed to the field behind us. “I have it growing right here! It’s interplanted with the mulberry. Want to go take a look?”

As we walked through the fields and talked with our new teacher we began to understand a little bit more about just where we were. Phu Pan is one of the many royal projects initiated by the King and Queen in the countryside that exist to provide people with skills and knowledge in crafts and agriculture. Water buffalo, durians, silk, rice, if it can be grown then you can bet they teach it. Aside from education there is also a consulting service available to those who want to know what crops their land is suitable for and how they can go about getting started. The sericulture department which we stumbled into teaches people the specifics of mulberry and silk production (and our wispy new teacher was, to our luck, the local indigo specialist) as well as weaving. Paid work is offered to weavers at the centre. The best part is that all of this is completely free. In a country where approximately half of the population is employed in the agricultural sector it is great to see such an amazing resource being made available to the public and must surely be one of the many reasons why the royalty is held in such high regard here.

After our walk through the fields we were invited to come back in September and assist the staff in their research on pigment concentration comparison between two species of indigo which would involve picking, processing and making a natural fermentation indigo vat. Needless to say, we accepted heartily. And that is how we find ourselves here again, next to the same mulberry and indigo field that just a few months ago was all but little seedlings. We can barely make out the outlines of the now vigorous plants as it is still pitch dark – the time being just before 4 am. All is still and silent. For a moment we think that perhaps our teacher has played a little joke on us but just then we spot beams of light darting out from deep within the fields – we are late and everybody is already hard at work. Hastily pulling on our gumboots we rush to join them in the dark.

kram picking

ann kram picking

Indigo has to be harvested early in the morning and processed as soon as possible to obtain the best results which usually means cutting the leaves in the wee hours of the morning and submerging them in water before they wilt in the sun. The plants we are working with have been planted in April and are now nearly 2 metre high robust bushes. Harvesting is a simple enough task involving nothing more than snipping away at the leafy stems leaving as little as 20-30 centimetres of the bush above ground so it has a chance to regenerate for a second (and potentially third) harvest. With a few other workers alongside us we manage to fill about 30 big buckets before the sun can fully rise.

kram buckets

These are then topped up with enough water to cover the leaves and left to soak for about a day.

after harvest

kram leaves

Next morning work starts at 4 am again and this time we experience the most labour-intensive part of indigo processing – the beating of the water. By this point the leaves had been soaking for about 22 hours and the blue pigment is now fully suspended in the water. The leaves are taken out and (being a nitrogen-rich legume) find themselves a welcome addition to the compost pile. Lime (Calcium Hydroxide) is then mixed into the liquid so that the suspended pigment can bind to it and sink to the bottom in a concentrated form, but in order for this to happen the liquid must first be beaten repeatedly to introduce oxygen. Each of us gets a special tool made just for this purpose which looks a bit like a lampshade on the end of a broomstick.

beating tool

We take this and then we beat. We beat and beat and beat some more. We beat with our arms and when they burn we find ways to beat with our whole body. We beat looking at the stars and then we beat to the sound of each other. Enveloped in darkness and plunging our lampshade broomsticks into the frothy blue waters in unison we notice something happen: we get dizzy, probably from the smell of slightly fermented indigo combined with the rocking motions. The other thing that happens is a change in the nature of the blue froth on top of the liquid. Initially it has a thick purple consistency with large oily bubbles that happily bob around content to stay where they are. As more and more oxygen is introduced this all changes until the froth is comprised of many tiny pale blue bubbles that quickly disperse with a hissing sound like that of an ice cube dropped into a glass of Coke. This is a sign that the pigment is no longer on top of the liquid and is now starting to float down to the bottom. There is no harm in going the extra step and beat a bit more, just to make sure you get as much pigment as possible out of your leaves.

kram beating

after beating

Once this is all done the liquid is left to stand until tomorrow. When we come back next morning we are pleased to know that the most physically demanding part of the processing is behind us. All that remains now is to collect the pigment which by now has sunk nicely to the bottom of the buckets. This is done by first gently pouring off the top portion of the liquid which has changed to a pale tea colour, indicating the absence of pigment.


The few handfuls of sludge at the bottom is the blue gold we are after. This is further reduced down by straining off any remaining liquid in buckets lined with tightly woven cotton.



By the next and final morning the blue mush is at its most concentrated form and feels a bit like heavy chocolate mousse cake. At this point the process is done and the pigment can be collected and stored in a protected container for up to 2 years. We take a deep breath and step back. Our teacher smiles and gently scoops out the indigo mush, being careful to get every last bit of it as we look on, exhausted and happy standing in humble silence and awe of the blue substance that radiates a quiet strength.

kram mush2

kram mush scoop

The whole experience has been eye-opening to say the least. All the human and non-human energy and time of planting, growing, tending, harvesting and processing now rest concentrated on the end of a metal spoon, breathing with potential and possibility. A newfound sense of respect and consideration comes over us for the plant, the people who work with it and the timeless body of traditional knowledge that they have allowed us to glimpse. For us this is an ongoing adventure carried out largely in the spirit of curiosity where we are just beginning to dip our toes in the indigo waters, but for the traditional dyers of the world this has been a way of life for countless generations. The colour of their life-blood is, overwhelmingly, blue. Our time at Phu Pan hasn’t quite ended just yet. In the next few days we start the equally interesting process of making a traditional natural fermentation indigo vat using the pigment that we helped to collect. But first, I think we will take a much-needed rest and enjoy the tranquil countryside of North-Eastern Thailand.

serg in field

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