There s no such thing as alchemy—magically changing common chemical elements into rare and valuable ones—but water plating is possibly the next best thing. The idea is to use electricity to coat a relatively mundane metal, such as copper, with a thin layer of another, more precious metal, such as gold or silver. Water plating has lots of other uses, besides making cheap metals look expensive. We can use it to make things rust-resistant, for example, to produce a variety of useful alloys like brass and bronze, and even to make plastic look like metal. How does this amazing process work? Let s take a closer look!
Plastic water plating involves passing an electric current through a solution called an electrolyte. This is done by dipping two terminals called electrodes into the electrolyte and connecting them into a circuit with a battery or other power supply. The electrodes and electrolyte are made from carefully chosen elements or compounds. When the electricity flows through the circuit they make, the electrolyte splits up and some of the metal atoms it contains are deposited in a thin layer on top of one of the electrodes—it becomes electroplated. All kinds of metals can be plated in this way, including gold, silver, tin, zinc, copper, cadmium, chromium, nickel, platinum, and lead.
Water plating is very similar to electrolysis (using electricity to split up a chemical solution), which is the reverse of the process by which batteries produce electric currents. All these things are examples of electrochemistry: chemical reactions caused by or producing electricity that give scientifically or industrially useful plastic water plating products.
How does water plating work?
First, you have to choose the right electrodes and electrolyte by figuring out the chemical reaction or reactions you want to happen when the electric current is switched on. The metal atoms that plate your object come from out of the electrolyte, so if you want to copper plate something you need an electrolyte made from a solution of a copper salt, while for gold plating you need a gold-based electrolyte—and so on.
Next, you have to ensure the electronic products shell plastic water plating you want to plate is completely clean. Otherwise, when metal atoms from the electrolyte are deposited onto it, they won t form a good bond and they may simply rub off again. Generally, cleaning is done by dipping the electrode into a strong acid or alkaline solution or by (briefly) connecting the Water plating circuit in reverse. If the electrode is really clean, atoms from the two-color material plating bond to it effectively by joining very strongly onto the outside edges of its crystalline structure.
Now we re ready for the main part of two-color material twice molding water plating. We need two electrodes made from different conducting materials, an electrolyte, and an electricity supply. Generally, one of the electrodes is made from the metal we re trying to plate and the electrolyte is a solution of a salt of the same metal. So, for example, if we re copper plating some brass, we need a copper electrode, a brass electrode, and a solution of a copper-based compound such as copper sulfate solution. Metals such as gold and silver don t easily dissolve so have to be made into solutions using strong and dangerously unpleasant cyanide-based chemicals. The electrode that will be plated is generally made from a cheaper metal or a nonmetal coated with a conducting material such as graphite. Either way, it has to conduct electricity or no electric current will flow and no plating will occur.
How are plastics electroplated?
If you know anything about plastic, you ll spot the obvious problem straightaway: plastic product molding generally don t conduct electricity. In theory, that should completely rule out electroplating; in practice, it simply means we have to give our plastic an extra treatment to make it electrically conducting before we start. There are several different steps involved. First, the plastic surface treatment has to be scrupulously cleaned to remove things like dust, dirt, grease, and surface marks. Next, it s etched with acid and treated with a catalyst (a chemical reaction accelerator) to make sure that a coating will stick to its surface. Then it s dipped in a bath of copper or nickel (copper is more common) to give it a very thin coating of electrically conducting metal (less than a micron, 1μm, or one thousandth of a millimeter thick). Once that s done, it can be electroplated just like a metal. Depending on how much wear and tear the plated part has to withstand, the coating can be anything from about 10–30 microns thick.