Copper tubs made in Santa Clara del Cobre are entirely handmade. Skillful craftsman use basic tools, often made by themselves or inherited from the previous generation. In general the production of the copper tub involves a lot of hammering, it is pretty nosy job. More less after a week of hammering copper and welding into the tub shape, a custom copper bathtub is ready for finishing touches.
In Mexico for coloring copper no chemical are used what is the norm in India, Pakistan and China. Those substances are corrosive and dangerous. They look very pretty but they are not healthy. What Mexican do it is heating copper what accelerate the natural patina creation. More heat the color becomes darker. Once the patina gained adequate tones and to prevent further oxidation, they varnish the copper while is still hot so the finishing material perpetrates copper deep making the patina color permanent.