Ann’s elder brother runs a café in Bangkok and has been coming by to drop off batches of old coffee beans for our use in natural dyeing. He is quite passionate about his work and makes sure to only use the very best beans within 6 weeks of their roasting date. Any older than that and the quality of the flavors begin to degrade, at which point they come to us. The taste may not be so great anymore but the pigment is still there.
To improve colour fastness on cellulose fabrics we first simmer the prepared cotton/linen in a tannin solution and leave it to soak overnight. The tannins (which we extract from simmering powdered Myrobalan nut) allow the mordant to “bite” into the fibre more effectively. On the second day the mordant (potassium aluminium sulphate or ferrous sulphate)is applied to the fabric either directly by brushing or by immersion in a pot and left overnight for better absorption. On the third day we extract the pigment by simmering ground coffee beans in a large pot and submerge the fabric, leaving it for yet another overnight soaking. It is a lengthy process but results in good colour. After dyeing in coffee if we want an overlaying pattern in another colour such as indigo on the same fabric we have to rework the fabric (take out previous stitching threads, wash, dry, plot new pattern, stitch and pull) and dye it again. While it takes time before we can see the final result it is also quite fun to experiment with new techniques and utilize an unexpected source of colour. Here are some of our latest coffee-dyeing experiments which will be patched together into an artwork for Hideaway café.