There are several different types of metal polish in the huge world of automotive detailing. Apart from the polish for paintwork there is also polish specifically for metal. These are mostly used for chrome bumpers, chrome trims, metal hubcaps, untreated metal wheels, exhausts and even engine parts.
The different types of polishes
The biggest difference between the polishes are:
Both of these can be done mechanically, but only chemical polishing can be done passively. While polishing metals the aim is to remove oxidation and sometimes to correct certain surface imperfections. Oxidized metal looks very dull, grey, very bad reflection and stains easily. A metal polish is a specific product aimed at restoring gloss, reflection, shine and a smoother microscopic surface. After polishing the metal can be treated with a protective product, maintaining the “like new” look longer.
Chemical polishes are products that have an effect on the evenness of the surface via a chemical process. These are often a bit easier to use, but provide less correction. Good for adding gloss and mirror-like finish, but less effective on corrosion or surface imperfections such as scratches.
This can be combined with mechanical polishing (i.e. movement), but in some cases can also be done by submersing the object in a series of bath with different chemicals. This process however is usually only done by specialist chemist, and rarely by a detailer himself.
A slightly more traditional type of polish, which uses very small parts that actually remove a very microscopic layer of surface to achieve correction. While removing a very fine layer of the surface, you also remove any surface oxidation. This type of polish is very effective on correcting any surface imperfections, but also requires much more mechanical cleaning. The polishing can be done by hand, by machine (like a rotary or ), but can also be done by immersing the object in a vibrating bath or polishing cones. Although this last type of polishing is less likely to be done by a detailer.
The reason to polish metal
Apart from getting dirty, metal is very sensitive to oxidation. Metal reacts with oxygen (like aluminium reacts to create a very thin layer of alumium oxide on the surface) and water (most famous example is iron that forms iron oxide (rust)). One of the reasons why cars got painted, was to protect the metal used to form the body and it’s components. Metal can obviously also get damaged by hitting it with an object. Apart from the risk of creating a dent, it might scratch the surface.
A metal polish will help to remove the layer of oxidation and to bring back the shine.
Difference in results
Metal polish can be used on many different types of metal, but it might give slightly different results depending on the material. Softer metals might be easier to correct, while harder metals can be easier to get maximum shine from.
The way of polishing can also make a difference, which can be read in the: how to polish metal. Different metals might also require different products. Some manufacturers make polishes that can be used on all kinds of metals, others try to perfect their product for a certain metal.