Bring the aluminum back to a mirror

Why does aluminum go dull and chalky?

Bare aluminum oxidises the moment it meets air — it forms a layer of aluminium oxide on the surface, and that layer is the dull chalky white-grey film you see. Unlike paint there is no clear coat over it, so nothing stands between the metal and the weather.

This is why a trailer that looked like a mirror when it left the dealer looks like a milk jug five years later. The metal is not damaged and it is not dirty. There is simply a layer of oxide on top of it, and the only way back is to cut that layer off and reveal the bright metal underneath.

Sun and salt air both speed it up, which is why Southern California coastal trailers oxidise faster than inland ones. Rain running off a roof edge will also leave vertical streaks of heavier oxidation down the sides.

Can pitted or rusted chrome be polished back?

Surface rust and oxidation on chrome polishes off and the chrome comes back bright, but pitting cannot be polished out — pits are holes where the plating has already failed, and no amount of compound puts plating back.

Chrome is a thin plated layer over steel, not solid metal. Once moisture gets through it and starts on the steel beneath, the plating lifts and pits. Polishing a pitted piece makes the flat areas shine and leaves the pits exactly as they were, which can actually make them more obvious.

The honest answer on badly pitted chrome is replating or replacement. We will tell you which pieces are worth polishing and which are not when we look at the vehicle, rather than polishing everything and handing you a bill.

How much does metal polishing cost in San Diego?

Aluminum, chrome and stainless polishing is priced by the square foot of metal being polished — $2.10 per square foot for a single-stage polish and $5.20 per square foot for heavy multi-stage work on badly oxidised metal. Cash or check prices are $2 and $5.

Square footage means the metal we actually polish, not the size of the trailer. Measure the height of the polished band and multiply by its length, then double it for both sides. A 24 ft trailer with a 2 ft polished lower skirt down both sides and a diamond-plate front comes to roughly 110 sq ft, so about $231 for a single-stage polish.

On cars and trucks, chrome and stainless polishing is included at no extra charge in both flagship packages — Stealth Diamond Borograph and Liquid PPF. As a standalone job on a vehicle it is quoted on what is actually there.

Heavily oxidised aluminum is what decides between the two rates. A trailer that has been polished before and kept up is single-stage work. One that has sat outside untouched for eight years needs the multi-stage rate, even though it is the same size.

How long does polished metal stay bright?

Bare polished metal starts oxidising again immediately, because polishing removes the oxide layer but leaves the metal exposed — so unprotected aluminum begins to dull within weeks and needs doing again, while coated metal holds the finish far longer.

This is the part worth understanding before you spend money on polishing. The shine is not a product sitting on the surface, it is the metal itself. Expose that metal to San Diego sun and coastal air and the clock starts over.

Sealing the polished metal is what changes the economics. We coat polished aluminum and stainless with Stealth Diamond Borograph, which puts a permanent barrier over the bare metal so it is not oxidising while it sits. Polishing without coating means paying for the same job again.

If you polish a trailer every season, coating it once will cost you less over three years than polishing it three more times.

Can you polish anodized or clear-coated aluminum?

No — anodized aluminum and clear-coated aluminum wheels must not be machine polished, because polishing cuts straight through the anodising or the clear and permanently ruins the finish.

This matters more than people expect, because a lot of trailer trim, RV window frames and factory alloy wheels are anodized or clear-coated and look like bare metal to the eye. Polishing them is not a mistake you can undo — once the anodising is cut through, the only fix is stripping and re-anodising the piece.

We identify what each surface actually is before anything touches it. On a clear-coated wheel the right treatment is paint correction and a coating, not metal polish. Getting this wrong is one of the most common ways a cheap mobile polish job costs someone a set of wheels.

Do you polish trailers on site?

Yes. Metal polishing is done at your home, barn, ranch or storage yard anywhere from San Diego County up to Temecula — the trailer does not need to be towed anywhere.

Horse trailers are the clearest case for mobile work. They are usually parked where the horses are rather than where the owner lives, they are awkward to tow for a cosmetic job, and the whole thing is done in an enclosed bay set up on site.

Plan on a full day or more for a heavily oxidised trailer. Metal polishing is multi-stage — a cutting compound first, then progressively finer compounds, then a final finishing pass — and every stage covers the whole surface. It is slow work and there is no shortcut that holds up.