The process of smelting has left us with very irregular shaped pieces of steel. Trapped with in this are multiple impurity’s, pieces of charcoal and air spaces. It is currently totally unusable. The past few days have been spent forging and fire welding together these chunks of bloom in to workable bars. This stage is really exciting for me as it marks a big step towards my end goal which is to use this hand made iron in my sculptures.
The first process is to get the bloom hot equally to the core. As it is not dense at this point it must be brought up to temperature slowly as it is easy to burn away the small outside pieces. We are forging using charcoal on a bottom blast forge. The Japanese style forge is lower than ground level, so you are working in a pit, and the anvil is set at height for the person working down there. This made striking quite an interesting experience for me to adapt to (especially as im quite tall) as it meant the anvil face is very low for anyone not working in the pit.
Our aim was to first tap in the extremities of the bloom slowly to make in more consolidated using a sledge hammer , very lightly at first! The next two photos show how it was when retrieved from the smelting furnace , and how it looks after a light forging.
We need to flatten the pieces and then stack them up and join them together by fire welding. The resulting piece ( made up of the two smaller bits) is then folded multiple times to draw out the impurity’s and make a more uniform material.
Other materials to prepare before the forging starts is the burning of rice straw to black ash pieces and the mixing up of a clay slip. These are kept near the forge and the bloom dipped in the ash first and then the slip just before fire welding. The ash acts as a natural flux and the clay slip protects the outside from loosing carbon.
The process is hot, hard work and also very time consuming. It made me really realise how much work is needed to make my own iron. It suddenly becomes a very expensive material!
The first few fire welds are more difficult as the bloom wants to break up. The clay and straw also help to hold it together in the fire whilst getting it up to temperature . We are looking for the surface to become glassy, a bright white colour and sparks seen in the flames.
Once it was holding together we could start using the power hammer and weld on a handle instead of handling it with tongs.
The power hammer was so useful and I am defiantly investing in one as soon As my workshop opens next year. Once the initial two pieces of bloom were fire welded together we used the power hammer to draw out the steel in to a bar shape. You can tell the weld has taken when the whole lump heats up together and there are no colour variations.
As there was slag trapped in the bloom and we are also dipping it in clay to fire weld, a lot of slag built up in the bottom of the forge . As it is a bottom blast forge this must be regularly cleaned or the air flow becomes blocked and the correct temperatures cannot be reached.
Once drawn out the bar was then cut almost in half at the middle point using a chisel, and then folded along this weak point.
Once it is folded in two it is dipped in ash and clay , fire welded together and then drawn out and split as just described . The whole process is repeated at least six times. This builds up the multiple layers in pattern welding, removes all the impurity’s and creates an nice forgeable bar!
It is an incredible amount of work to get to this point before anything creative can be done with it! I’m totally in love with the process though and can’t wait to develop work with the steel.