A simple resource efficient dyeing system
One of our interests in setting up Himalayan Weavers was to promote the use of natural dyes on wool. As Pat and I did not have any knowledge of or expertise in dyeing, we learnt the basics from the internet. The first lot we dyed was about 2 kilograms of hand spun wool we had bought from a Bhotia family in Dunda village near Uttarkashi. We dyed it red with madder which we bought from a seller of Auyrvedic material in Dehradun. The actual dyeing was done in our kitchen in Masrana. We took the dyed yarn to a weaver in a near by town, Dhanaulti, and got a few scarves hand-woven to Pat's designs. Encouraged by our success with madder, we tried other materials including tesu (flame of the forest) flowers, henna, pomegranate reed and catechu.
We began dyeing wool yarn in small pans, heating dye bath using a domestic gas burner. But we felt that heating a dye bath on an open gas flame resulted in considerable loss of heat and energy. As a more energy efficient alternative, we tried cold dyeing in which we left the wool to be dyed in a bucket at room temperature for a few days. Although successful for most dyes, this method was not practical for large scale dyeing. We would have needed hundreds of buckets and a lot of space to keep them. So, this also was not a good way to dye the large amount of wool, which we needed to do as a business.
Our next attempt was to build tanks with immersion heaters and thermostats. The tanks were insulated with high quality insulation sheets to conserve heat, and that reduced our consumption of electricity. But we faced another problem! The temperature of the dye bath was higher near the heater (bottom) and lower at the top. This caused some unevenness in dye absorption and colour shade. Although the results were acceptable on the whole, we were not very satisfied.
Then about four years ago we hit upon the idea of wrapping electric blankets around recycled 100 litre tanks and covering these with insulation sheets. These blankets keep the dye bath uniformly warm and produce dyed yarn of excellent quality. Also, as the blankets consume very little electricity, and there is no heat loss from the tank, the system is highly energy efficient. We have about 10 tanks, one for each dye and we use the same dye bath for many months. As we don't replace dye bath frequently, this saves a lot of water. On the whole we are very satisfied with our new system. It is simple, resource efficient and produces dyed yarn of excellent quality.