The "SUCCESSFUL" hard industrial chroming of any type of brass alloy only requires a general physical cleaning & then a chemical cleaning in a strong alkaline solution. However, the "SUCCESSFUL" hard industrial chroming of aluminum is a very different situation! Aluminum alloys must be carefully cleaned physically with Dawn, a rotating brush & hot water. The cylinder is then "immediately" placed in three different chemical baths, for a specific measured amount of time for each bath. In between each bath, the cylinder is washed in hot running water. After the final immersion in the last bath, the cylinder is washed in hot running water & then it is "immediately" placed in it's chroming fixture. MISS ANY STEP IN THIS PROCEDURE & YOU WILL HAVE A PITTED, FLAKING OFF, NOT HARD, CHROME PLATE!
The typical basic Chromium Trioxide bath should be operating at 125 to 130* F. The bath's temperature & current density will affect the hardness of the chrome plate. A typical .45 size liner will run at 13.5 amps for 58 minutes providing the electrical contacts between the cylinder, the anode, the cathode & the power supply are "absolutely sound". This current & time will put on approximately .0015" of chrome per side. Any bad connection anywhere will generate unwanted heat & raise the necessary current density amount! The power supply should be as ripple free as possible. The power supply should have an adjustable current & voltage output. There should be a precision amp meter & volt meter between the power supply & the chrome bath. A typical basic chromium bath will plate approximately 200 cylinders.
As previously stated the necessary chemicals used for aluminum alloys are very corrosive & dangerous! The chrome tank emits very heavy fumes when in operation & it should be operated in a controlled environment. No decision has been made concerning the release of information about the chemicals being used.