When I first heard that the Piramal art foundation was doing a dokra workshop I was intrigued. Dokra, is a technique of investment casting of brass also called the lost wax casting technique. I could not figure how they would do this casting, after all the brass would have to be melted and poured into the casts and that's fairly dangerous to do. I paid a fair amount for 2, 4 hour sessions and was quite disappointed by the content of the workshop. You see we were only going to be doing the wax sculpting. There would be no mold making and most definitely no molten brass. BUT; and this is a big but, I met Mandakini Mathur, a kind of beacon of hope for the dokra craftsmen of naxilite hit areas Gadchiroli and Bastar. She along with Suresh Pungati, a renowned dokra artist, has, since 2008, been trying to provide a safe space for advasi craftsmen to work, innovate and thrive in a 2 acre plot in Panchgani.
The is the basis behind the Devrai Art Village. The DAV, now employs about 35 crafts-persons. A few of the craftsmen have moved with their wives and children, who are also now, learning dokra work. I spoke to a few of the 1st generation artisans. Apparently in their villages, dokra when sold, is sold by weight. There is no marketing and there is no other job. One can farm or join the police or join the naxalites. These are the option, each option is no better than the other for these Adivasis. So for them, the DAV is the only hope of a safe life; and for the rest of india the DAV is the only hope to save a dying craft.
I immediately made plans with Mandakini to visit, learn and document what I had learnt. I wanted to see the process from end to end, I had a million questions, I needed to see how the clay was put on the wax sculpture, how did it take detail, how was it strong enough to withstand the heat of molten brass. Mandakini was kind enough to arrange a 4 day workshop for me. I would leave mumbai early monday morning and come back friday noon. The schedule she had worked out went roughly like this and obviously follows the process of dokra work
- Monday - Wax sculpting with the artisans
- Tuesday - First layer of fine clay
- Wednesday - Second layer of clay
- Thursday - Brass casting
- Friday - leave early morning with wonderful cast objects.
For those who have not been paying attention in schools when this was taught, here's a quick refresher.
Wax is sculpted into the shape of the final object, all the details and embellishments are made in the wax or put on the wax and then the entire wax sculpture is coated with clay. The clay is worked into all the nooks and crannies of the sculpture and then the entire thing is fired. The firing melts the wax and hardens the clay which is now a simple mold. Bras iss melted and poured into the mould and then when the metal has solidified and cooled the mold is broken. Polishing and buffing is done and the object is ready for display
The schedule was followed much as it was, we even got some siteseeing done in the time between clay layers drying up. Moreover, the DAV needed to make a kind of an installation for a hotel nearby and i got to work on mixing my woodworking with their dokra work to create some fascinating information signage.
What follows in this post is a documentation of recipes, techniques and insights that may be quite off target but are still important since they may be points that I couldn't get clarified from the artisans.
Day 1: Wax sculpting:
The wax is a mixture of paraffin wax, beeswax, dhoop ( sap of the saal tree) and bitumen. I was told that too much dhoop would added to harden the wax and that too much beeswax would make it too runny. Which meant that dhoop raises the softening point and lowers the workability of the wax, whereas beeswax lowered the melting point and made the mix pliable longer. I suspect that bitumen was added to replace beeswax as it is cheaper and does exactly the same thing, which is to lower the melting point and to keep the mixture pliable. Paraffin wax serves as a base adding body but is too crumbly.
The wax mixture is boiled for hours, (all approximations) and then poured on water to obtain sheets. Balls of it are also put in to "sali makers" to get long threads of various thicknesses. There is a fair bit of documentation of this on youtube so I'm not going to repeat it.
Like all casting techniques, one has to be aware of how the molten metal will flow into the mold and take care to build in channels to bridge difficult to get too place. This is a science in itself. Software does exist to do this, but it is expensive, so experience and trial and error must make do instead.
Day 2: First layer of clay
The first layer of clay is meant to take the details from the wax. The layer itself has very little strength and if the wax is not hard enough, the weight of the clay will actually deform the sculpture. Perhaps this first mud layer should always be put on, when the ambient temperature is low; early morning or late afternoon. Another thing is that the mud was actually very sandy as if clay was mixed with very fine sand. The clay is brought in by the truckload from Gadchiroli, since it harden very well and doesn't crumble when fired, which the good soil of the konkan region is wont to do.
The water content of the mix MUST be low. If too much then during drying, voids are created or worse cracks form. Cracks are obvious disasters, but the voids took me longer to understand. The craftsmen are just aware that too much water causes problems and will not say, or do not know that spaces created in between the particles of clay are filled by brass during the casting process, leading to wastage of brass as well as adding to the difficulty of cleaning up the piece later.
Day 3: Second layer of clay
The second layer is the strength layer. While the first layer has probably got fine sand mixed in, the second layer has a handful of rice husk mixed in. The rice husk holds the clay together and during firing will actually burn and help the clay heat up faster. Again here there is no specific amount of husk to be added. We can infer that too much would interfere with the bonding of the clay and too little will not provide the fuel for burning inside the walls of the second layer. Again here, the "packing" had to be done just right and one of the craftsmen helped us put on the second layer. We saw later that we had not packed it just right, we had somehow left a gap between the two layers and during pouring this gap was filled with molten brass, hence some of the pieces when the mold was broken, had a brass sheet which had itself to be broken to get to the inner layer of clay. Wastage again.
Day 4: The big day... Casting
The furnace is an old style, hole in the ground with thick clay walls providing insulation. A pipe driven into the base of the hole provides air/oxygen and all in all the whole affair is very villagey. The only "new", is the graphite crucible.
Second hand brass is bought from scrap dealers and everything is melted together regardless of the variant or grade of brass. I doubt it matters anyway. The process has to be seen to be believed, although it is most definitely not something scene out of hell.
When the brass is sort of half way melted and coming up to white hot, the molds are placed in a make shift furnace close by and fired. This is important. On probing we learnt that the molds MUST be at about the same temperature as the molten brass else the brass would begin to solidify before reaching the very ends of the mold. And now it becomes clear what the rice husk is for. During firing the rice husk burns and make the inside of walls of the mold hot, which in turns means that there is a nice even temperature between the inner wall and the outer wall of the mold. The brass flows freely and the mold is not shocked when the molten metal is poured in.
Things that need doing
1. Analyse the 2 layers of clay for exact components. (A simple clay separation test will suffice, like is done with testing of mortar on restoration sites)
2. Analyse the chemicals in the mud/sand itself. (This will probably require a lab)
3. Experiment with the effect of too much water in the mud layer. The brass actually creates some really unique effects.