How to: Polish alloy to a mirror shine

30 October, 200718 yr

How to: Polish alloy to a mirror shine

So you want some bling in your life. Well you have two choices. Either get someone to do it for you or do it yourself. I've used both methods. Generally speaking, I won't polish large items myself... mainly because whilst I can polish, I don't have large/good enough tools to do large items. In this FAQ I'll run you through the basics of polishing alloy, starting with a fine casting and ending up with a mirror shine.

First off, you'll need the following kit:

· Work bench & vice (or something to hold either a drill or the piece you are working on)

· A drill (mains powered)

· A dremel tool (15k rpm)

· Polishing wheels, abrasive material & polishing compounds

· Arbors

· Various grades of Aluminium Oxide and Silicon Carbide paper (Wet & Dry)

· Cleaning fluids

· Patience

The fine details of the kit list, I'll leave up to you, however to do a throttle body cost about £2 in materials. For a polishing kit, I would recommend Frost's Polishing and Abrasive kit.

My item before

Cleaning

Before starting on your piece, you'll need to get rid of any oil or crappy mess. Strip the object down as much as possible. Rocker covers, inlet manifold etc should present no problems. In my case, the throttle body could only be stripped so far.

To remove the oil and general road gunk, I used a combination of watered down Viro-Sol (5:1) in a garden spray and budget White Spirit with a tooth brush. Use the tooth brush and White Spirit to loosen the dirt and wash away with the Viro-Sol. Wash the object in warm water once you are happy with it.

After cleaning

Note the shape of the throttle body before working on it

Abrasive stage

With any metallic object when polishing, the first step always involves removing the casting marks. Depending on what you are actually polishing, you may find finer casting marks or in the case of wheels, no casting marks at all. A good starting point is 80 grade Aluminum Oxide. I cut circular disks of about 1.5" diametre to use on a dremel and also using abrasive wheels on a drill at this point. Keep cutting the alloy with various grades getting finer with each step and alternating direction. You will know when you've finished with a given step as you shouldn't be able to see the 'cut' from the previous step. I normally go as far as 400 grade Silicon Carbide before embarking on polishing.

Reshaped internals

Throttle body after 400 grade paper

Polishing stage

This is usually quite easy. With the right kit, all you need to do is add the polishing compound to your polishing wheels on a drill and run them against the alloy piece. The initial polish will look dull. Remove the excess compound with Vienna lime and a cloth before starting with the next wheel. Dremel polishing kits are useful for small items or awkward areas.

With the final polishing stage complete, wipe the item over with Vienna lime and then apply a polishing liquid. My favourite is AluMagic as this not only gives a great shine, but contains a wax for protection. Your finished piece should look something like this:

Mirror finish