The Bombarding Process Explained

The Bombarding is the process in which the neon unit is heated up and at the same time the vacuum pump extracts all the air out of the unit.
The parts of the bombarding equipment are ;

The high voltage transformer
The vacuum Pump
The Manifold System

At a certain vacuum the air inside the glass will conduct electricity , electricity that is produced by the high voltage transformer, and will at the same time due to the high voltage and amperage used will heat up the glass , heat that is needed to purify the inner walls of the glass in the neon sign . At the same time the vacuum pump will extract the burned impurities that have been burned by the heat produced. After there is no indication in the gauge that is monitoring the pressure that there is no more increase in pressure caused by the burning of the impurities and the electrodes have reached a orange red hot glow , then the electricity is turned off and the main valve is opened to let impurities and air out by means of the vacuum pump, and at the same time the unit is left to cool down . When the unit is cooled to room temperature and a vacuum of at least 2 microns is reached then the vacuum pump valve is closed and the gas valve is opened (either neon gas or argon gas) to injected the gas into the neon unit. Then the unit is sealed by means of a hand torch and if it’s a mercury unit the mercury is transferred from the temporary bubble deposit into the neon unit then the excess tubulation with the bubble is separated from the neon unit and discarded.
Mercury is only used when using argon gas, when using neon gas you don’t need mercury.