Dr. Wack "P21S" P21S "Metall-/ Alu-Polish" Metal Polish 100ml

P21S "Metall-/ Alu-Polish" takes the oxide off and leaves the metal standing

What is the P21S "Metall-/ Alu-Polish"? A white, paste-style metal polish from Dr. Wack that mechanically takes the dull oxide layer off aluminium, chrome, stainless steel, silver, brass and copper and leaves a protective film behind. Not for anodised surfaces and not for chromed plastic.

P21S "Metall-/ Alu-Polish" is a metal polish from Dr. Wack that uncovers bare surfaces again instead of coating them. Aluminium, chrome and stainless steel react with the oxygen in the air and pull on a wafer-thin oxide layer that scatters light instead of mirroring it. You know it from the silver cutlery in the drawer: it does not get dirty, it tarnishes. For you that means no cleaner shifts that dull grey, it has to be taken off.

The data sheet does not list a pH value for this product at all, it simply says “not applicable”. The paste is not water-based, so there is neither acid nor alkali that could work on the metal. What comes off comes off by pure abrasion, steered by pressure and by the lines you work in. In practice: leaving it on too long does the metal no harm, it only makes wiping it off more of a chore. What you dose here is pressure.

The paste is mixed in Baar-Ebenhausen, and its density of 1.22 grams per cubic centimetre at 20 °C gives away what is in the tube. Although almost half the formula is volatile, it weighs a good deal more than water. That weight comes from the solid abrasive bodies, which is why 100 ml of contents put 122 grams on the scales.

Then there is the consistency. The data sheet quotes a viscosity between 2,000 and 6,000 millipascal seconds, which is thick honey territory. Day-to-day you notice it because the paste stays put on a vertical tailpipe instead of running off before you have worked it in.

• Six materials out of one 100-millilitre tube. Aluminium, chrome, stainless steel, silver, brass and copper are all on the approval list, painted or bare. For the chrome strip, the stainless tailpipe and the brass fitting on a classic you do not need three products, you need one tube and three clean wads of polishing wadding.
• 129 out of 155 points in the chrome polish test. AUTO BILD ran nine chrome polishes against each other on 4 May 2026, and the Metall-/ Alu-Polish came out on top with the verdict “highly recommended”. 100 of the 155 points hung on the finish pattern and the surface gloss alone, so on the question of how clean the cut looks once you are done.
• The flash-off phase is evaporation, not waiting. Around 48 per cent of the formula is volatile. In the short pause between working it in and wiping it off, that carrier goes into the air and leaves the protective film behind on the exposed metal. You notice it like this: on a warm day the film goes matt and ready to wipe faster than it does somewhere cool and shaded.

Detailing1's tip from the shop: We see the most expensive mistake regularly before the tube is even open — anodised and clear-coated aluminium looks like bare metal but carries a protective layer that this polish takes off with everything else. So run the white cloth test: a pea-sized blob on a white cotton cloth, rubbed on a hidden patch for twenty seconds. If the mark goes grey to black, you have bare metal in front of you, because that residue is the oxide layer. If the cloth stays white, there is anodising or clear coat on top, and that is where the polish stops.

You polish the whole strip, never just the dull patch.

The paste goes onto polishing wadding and not straight onto the metal, gets worked in with pressure, flashes off briefly and is then wiped away with a clean microfibre cloth.

Wash first, dry second, polish third. On a dirty surface you grind loose grit along under the wadding, and the fine lines that leaves show up more clearly on polished metal than on paint. A surface that mirrors shows every mistake twice over.

The reason for the wadding is dosing. Put the paste straight onto the surface and it sits too thick in one spot and spreads unevenly on the first pass. On the wadding the same amount spreads across the whole contact face, and the pressure from your hand arrives evenly at the metal. That is exactly what sits behind the AUTO BILD sub-score for spreadability.

The second rule is in small print on the tube and gets skipped over constantly: for an even result you always work the whole surface. Go at the dull patch on the tailpipe on its own and you end up with two states side by side and a visible line between them. A chrome strip gets done edge to edge, a tailpipe all the way round, a wheel as a whole.

On painted surfaces, painted alloy wheels for instance, the manufacturer explicitly calls for minimal effort. There is no oxide there, there is paint, and paint will not take the pressure bare metal needs. If you are doing several metal parts in one go, the metal polishes from Dr. Wack also run to the motorcycle version, built around the same way of working.

Brown speckles on stainless tailpipes are usually fallout, foreign iron particles that have taken hold. The polish takes those off mechanically. A chemical decon step does dissolve them more gently, but it does not bring back the shine the surface needs afterwards.

Anodised alu does not get polished, it gets taken off.

Anodising is not paint and not colour, it is an oxide layer grown on the aluminium in a bath, so exactly the material this polish is built to take off.

The paste plays to its strength wherever bare metal is out in the air: stainless tailpipes, chrome trim on a modern classic, unpainted forged wheels, motorcycle parts, brass and copper fittings. There is a genuine oxide layer there, and the dark streak you see on the cloth afterwards is the proof that it is off.

The manufacturer draws two hard limits. Anodised aluminium stays off limits, because the anodised layer is itself the protection and the abrasion simply takes it with it. What appears underneath is unprotected raw material. And on chromed plastic parts the paste has no business: the chrome sits there as a wafer-thin metal film on the plastic and you have polished through it before you notice.

What the paste also does not do: deep scoring, pitting and corrosion that has already eaten into the material. It works at the surface, not down in it. If you are bringing a chrome strip or a tailpipe up to a mirror shine by hand, this is the right tool. If a large dull alu panel has to be cut back by machine first, you reach for the metal polish with a medium cut and come back to this paste for the finish.

The shine is a state with a shelf life, not a result.

Bare metal starts reacting with the oxygen in the air again from the first moment, which is why metal polish is a rhythm and not a one-off appointment.

That is exactly what the protective film left by the paste works against. It slows the tarnishing, it does not stop it. How long it lasts is something Dr. Wack deliberately does not state for this product, and that is fair enough: a tailpipe in winter use stands in a different place from a trim strip on a car kept under cover. On wheels you put a wheel sealant from the same line over the top and stretch the interval noticeably.

The tube makes sense for anyone living with unpainted metal on the car: modern-classic and classic drivers with chrome, riders with polished parts on the bike, detailers who do the stainless tailpipes as the last job before handover. It makes no sense for someone after a permanent fix. If you never want to polish again, have the surface clear-coated and look after the paint from then on, not the metal.

Commercially that makes the 100-millilitre tube not a small size but the right one. A pea-sized blob goes onto the wadding per pass, and anyone who keeps to the rhythm gets through less of it than someone working against a full year of oxide once a year. Store it frost-free, tightly closed and away from food.

The trick no tube prints on the label: do not reach for the polish once the surface has gone dull, reach for it while it still shines. On freshly tarnished metal a light pass is enough and barely anything stays on the cloth. On two years of oxide the same shine costs you real material, and what once sticks to the cloth does not come back. Aluminium does not grow back.

How to use the P21S "Metall-/ Alu-Polish"

From the wadding onto the metal, not the other way round

The surface has to be clean and dry before the first pass. Loose grit under the wadding drags lines in, and those stand out more on mirrored metal than on paint. So wash first, dry it off, let it cool, then shake the tube.

Put a pea-sized blob onto a wad of polishing wadding, not straight onto the part. Work it in with pressure, in straight lines along the edge of the part. On anodised or clear-coated aluminium you do not polish at all, or you take the protective layer off. Painted surfaces such as painted alloy wheels explicitly get minimal effort only.

Then let it flash off briefly. The film goes matt as soon as the volatile part has evaporated, and that is exactly when you take it off with a clean, dry microfibre cloth. A cloth kept only for this job suits it, the premium microfibre cloth from the A1 line for instance.

The dark residue on the cloth is the oxide layer you have taken off, not dirt. It tells you whether you are working on bare metal at all. If one pass is not enough, repeat it with fresh wadding. What stays important: always work the whole surface, or you see the border between done and not done afterwards.

Notes: Do not use it on anodised surfaces and not on chromed plastic parts — both carry a thin protective or metal layer that comes off with the polishing. Deep scoring, pitting and corrosion that has eaten in are beyond the paste, it works at the surface. If you are unsure about the state of the surface, the white cloth test on a hidden patch helps: dark residue means bare metal, a cloth that stays white means anodising or clear coat. The tube belongs stored tightly closed, frost-free and away from food.