Under the normal working conditions, the easiest way to blacken the surface of the electric heating tube is as follows:
1. Clean the surface of the metal tube and keep it clean.
2. The surface is degrease. This process allows the metal tube to be completely placed in the degrease solution. The pH of the degrease solution is preferably around 13, and the time is not less than half an hour. Wash off with water after degrease
3, can be pickled, pickling solution PH value of about 3, the treatment time is not longer than 10 minutes, after pickling, rinse with water.
4, blackening treatment: pool liquid concentration PH value 2-4, processing time 10 minutes up and down, after the black is incomparably clean.
5. Dry and oil.