Menuki done with Uchi-Dachi

    Authentic Japanese menuki were made with a technique called Uchi-Dachi. This is a distinctly Japanese process that blurs the distinctions between what is commonly  known as Metal "sinking" and metal "raising".

A menuki is a hollow form made from a flat sheet of metal. Using dachi tagane, metal around the design is driven down and inward while sitting on a bed of warm  semi soft pitch. This creates a hollow form with slightly tapered walls and a domed top. If done properly the walls or "skirt" will "upset". In other words become thicker that the original sheet of metal you started with.

In antiques the bottom edge of the skirt can be very thick in some spots and thinner where the metal had to stretch more such as inside corners. The overall appearance is generally thick. This is not hard to do on larger object, but when you are doing something as small as menuki it can become more difficult.

A unique aspect of Uchi-dachi is that no metal tools ever touch the back of the work. It is completely formed from the top down while sitting in a soft Matsuyani (black pitch). This is evidenced by the unique surface found inside menuki and the complete lack of tool marks. Even signatures when present are normally engraved on a separate tiny plaque which is installed in the back the menuki. On larger objects sometimes a wooden punch is used on the back to start the doming process off. For tiny items at least in my experience the doming occurs naturally.

For me the challenge in this technique is not one of making functional menuki. They are not demanding structurally. They can be carved out of a solid and work just fine. The skirt can be razor thin its not really a problem. However for a completely authentic appearance this hollowed upsetting needs to be present. The problem or challenge is to keep the metal from stretching downward as you try to upset it. At first my attempts left me with more stretching and the metal would end up thinner than it started. With practice I have managed to find the middle ground where the stretching and upsetting cancel each other out. I am not losing thickness, but I am not gaining much either.

The Complete lack of tool marks on the interior surface and the pronounced upsetting in the wall thickness are indicators of skilled craftsmanship. At the same time the respect given the unseen shows a great pride behind the curtain as well as infront of it.

The bottom gets filed to the right height. This reveals the final wall thickness of the skirt.


1mm thick Shakudo sheet is cut out and set in the Pitch bowl. Some of the Dachi tagane are layed out next to the bowl.

The slide show below shows the progress after each annealing cycle.

 

 

 

Here is the menuki after trimming the excess material. All of the shapeing has been chased in and its ready to move on to the refinement stage were I will pull out the chisel and scrapers and bring the details into focus.


After chaseing to completion the menuki Selectivly gilded and polished to prepare for Niage.
After Niage the Shakudo turns a deep blue black. The gold is not affected by the niage.
The finished menuki...