Etching galvanised steel is more difficult than etching stainless steel even with the introduction of low-voltage current because the process of galvanising protects the metal, making it resistant to chemical interaction. To achieve an artistic acid metal etch with galvanised steel it's necessary to remove as much of the surface protectant as possible. This is done with a mild abrasive pad or fine sandpaper. Once all protective coating is removed, the acid etch reaches the steel and etches the desired artistic design into the metal just as with stainless steel.
Choose a design for the artwork to be etched and use waterproof ink to draw it on the galvanised steel, or print a black-and-white picture onto a glossy ink jet paper with a laser printer set on its darkest, best quality setting.
Buff the galvanised steel with an abrasive pad or fine sandpaper to remove the galvanised coating, and draw the design onto the metal. Or, if using a printed photo or picture, position the picture ink side down on the metal and press and hold an iron on its hottest setting for approximately 5 minutes to the back of the picture to melt the ink of the picture onto the steel, then let it cool for about 30 minutes.
Fill a plastic dish tub with hot water and submerge the steel in the water to soften the ink jet paper, then peel it off--it comes off in strips and layers--until there is only a thin layer left on the metal, then remove the last of the paper residue by rubbing the face of the metal lightly with the fingers. Rub carefully so the ink is not smudged. Set the steel on a paper towel until it's dry, and empty and dry the plastic tub.
Put on a pair of protective gloves and a pair of protective goggles or glasses to protect the eyes.
Mix the ferrous sulphate according to the manufacturer's instructions in the plastic tub. Mix and fill the tub with enough to cover the steel.
Bend each of the braising rods into a "U" and turn the pieces so that the sides of the "U" shapes are in the acid bath and the bottom of each "U" is sticking out of the acid bath. Make sure the two brazing rods are placed one on either side of the inside of the acid bath's plastic tub.
Use a sharp knife to gently cut and strip an inch of the plastic casing off the power cord at one end, leaving the two interior wires intact. Connect both of these wires to the positive battery terminal. Use the knife to cut and strip the plastic casing off of the other end of the power cord and attach one wire to each brazing rod.
Use the tongs to lower the steel into the acid bath and agitate the acid bath every few minutes. Use the tongs to remove the steel after 30 minutes.
Hold the metal under clear running water to rinse off the acid, then rub gently with a soft cloth to remove any discolouration produced by the chemicals in the acid.