Cleaning and maintaining metal finishes

At a glance

Sources: Euro Inox Vols. 15 and 16; BSSA 7.20; CCI 9/3; a US maker's care sheet; AAMA 609 and 610. A finisher's own care sheet overrules this table. Test every product on a hidden spot first.

Three rules that cover most of it

• Clean for the finish, not the metal. A brass-coloured handle may be solid brass, brass plate, lacquered brass or PVD, and each wants a different method. Find out which before choosing a product. Our ironmongery finish codes sheet shows how to read that from a schedule.
• Mildest first, and test. Soap or detergent in water, a soft cloth, a clear rinse and a dry wipe. Every source we read asks you to try any stronger product on a small hidden area first, and to rinse and dry afterwards. Never mix cleaners: AAMA warns that bleach and ammonia together give off poison gas.
• Keep tools and chemistry apart. Use cloths and pads kept for stainless steel only: iron left by steel wool or a wire brush rusts on the surface (Euro Inox). Check what a cleaner does to its neighbours as well: acidic stainless cleaners can damage aluminium, galvanised steel and stone (Euro Inox).

How often is a question of use and place. The British Stainless Steel Association's rule of thumb is to clean the metal when it is dirty, which it puts at one to four times a year outside and daily in hygienic uses, and more often in a swimming pool building, where heat and humidity discolour stainless. AAMA asks owners to take the cleaning schedule from the finish supplier, and notes that sheltered, recessed areas soil more because rain does not wash them.

Which cleaner can each finish take?

The chart rates eight kinds of cleaner against six finish groups. Each caveat names its source. Where no source we read covers a cell, it says Ask: that means “ask the finisher”, not “safe”.

Key. OK: usually fine. Care: only as the caveat says, and tested first. No: avoid. Ask: not covered by a source we read, so get the finisher's written advice. Where a cell rests on our reading rather than a named source, the caveat says so.

Notes by finish family

Stainless steel, PVD and coloured stainless

Stainless steel does not need a coating to resist corrosion, but dirt that holds chlorides or iron can break down its protective film, so cleaning protects the metal as well as the look (Euro Inox). Points that matter at handover and after:

• Protective film. Take it off once it is no longer needed. Sunlight can make some films hard to remove and leave adhesive on the steel.
• First clean. Rinse, wash in warm water with soap, detergent or 5 per cent ammonia, rinse, then wipe dry in overlapping strokes from top to bottom, along the grain on brushed finishes.
• Site iron. Grinding or cutting carbon steel nearby, tools and scaffold leave iron on stainless. It rusts, and can start pitting. Order the work so that tiling and mortar cleaning are finished before stainless skirtings or kick plates go in.
• Mortar and cement splashes. A warm 10 to 15 per cent phosphoric acid solution, neutralised with dilute ammonia and rinsed. Mortar removers based on hydrochloric acid must not touch stainless.
• Fingerprints. Soapy water or mild detergent is usually safe. Brushed finishes can show fingermarks just after installation, and Euro Inox says the marking becomes less evident after the first few cleans. Polished and mirror finishes show marks first.
• Coloured and PVD. The colour depends on a thin film that is more delicate than the steel, so abrasive techniques are unsuitable and repair is by replacing the panel (Euro Inox). Some hardware makers write that PVD is almost unaffected by cleaning agents. Euro Inox asks for great care, so follow the coating house's written care sheet.
• Tea staining and rust marks. Brown staining under dirt is the start of corrosion. Euro Inox calls the acidic treatment that removes it remedial cleaning and leaves it to experienced specialists.

The BSSA information sheet (2001) gives cleaning intervals for stainless in architectural use. They are older than the Euro Inox text, so treat them as a guide:

Brass, bronze and copper

The first decision is whether the metal is lacquered or left to age. A lacquered surface is cleaned gently: soft cloth, mild soap and water, and no brass polish unless the aim is to strip the lacquer and refinish. An unlacquered, living surface will darken and vary with use whatever is done. The sheet on lacquered and unlacquered brass and copper sets out that choice, and our journal on patination shows how the metals age.

• Polishing removes metal. The Canadian Conservation Institute notes that polishing is abrasive: it removes tarnish and some of the surface, so repeated polishing loses detail. Use the mildest method that works.
• Skin. Clean cotton gloves avoid putting moisture, salts and oils from fingers back on freshly cleaned metal. In a hotel that is not practical, so the answer is a regular wipe.
• Polishes. Many contain ammonia, which can dissolve copper in some conditions. Car and stainless polishes can contain hard particles that scratch soft copper alloys, and some leave a film that makes later work hard.
• Wax. A microcrystalline wax with no synthetic components, applied thinly and buffed, reduces how often the metal needs cleaning and polishing (CCI). One hardware maker uses a paste furniture wax on oxidised, oiled bronze, buffed lightly so as not to remove the dark layer.
• Lacquer. CCI warns that lacquer always changes the appearance, is hard to apply thinly and hard to remove, and calls for a specialist company. Treat re-lacquering as a workshop job, not a cleaning step.

The CCI note is written for museum objects, where handling is gentler than in a hotel. Use it for what damages the metal, not for how often to clean.

Powder coat and anodised aluminium

AAMA 609 and 610 covers both. Its core advice: flush with water, then use a mild detergent with a soft brush or sponge, rinse well and dry; clean in the shade and never on hot surfaces; work from top to bottom. Do not use aggressive alkaline or acid cleaners. On anodised surfaces it names trisodium phosphate and phosphoric, hydrochloric and hydrofluoric acids and fluorides, and notes that mortar, cement and other alkaline materials corrode anodic coatings if they dry on them. For painted and powder-coated surfaces it allows a mild solvent such as mineral spirits for grease, warns that stronger solvents soften paint, and says not to rub hard because that can change the texture or add shine. It is a US guide dated 2009, and the finish supplier should give the schedule.

The handover pack

Our aftercare page says a care and maintenance guide is produced for each commission. This table is the metal part of it. Write one row for every visible metal finish, with the product named, and ask the finisher to read it before handover.

• Add the paperwork. The finisher's written care instructions, the approved reference sample kept with the owner, and any warranty conditions about cleaning products.
• Say what is living. Where the client has accepted a finish that will change, such as unlacquered brass, record it, with the date.
• Stop and ask. Rust or tea staining on stainless, heat tint, graffiti on coloured or coated metal, failed lacquer, and any damage to PVD or anodising are specialist jobs. Euro Inox leaves remedial cleaning of stainless to experienced specialist companies and graffiti on coloured stainless to specialist cleaners.

The operation and maintenance manual is to list, for every visible metal finish: the finish in words and code; the routine cleaning method and named product; products and tools not to be used; the cleaning frequency [ ]; how the finish is restored and by whom; and the finisher's written care instructions [attached]. The finisher is to review the entries before handover.

Remove protective film within [ ] weeks of fixing, or the film maker's stated maximum. Before handover: rinse; wash in warm water with [soap or neutral detergent]; rinse; wipe dry along the grain. No chloride products, steel wool or non-stainless pads. Remove site iron contamination. No hydrochloric acid products where they can reach stainless steel.

[Unlacquered brass] on [door pulls, bar rail] is accepted by the client as a living finish [sign-off date]. It will darken and vary with use. Routine cleaning: [soft cloth, mild detergent, water, dry]. Polishing only on instruction from [ ]. No ammonia-based or abrasive polishes.

Powder-coated and anodised aluminium: clean with [mild detergent and water], rinse and dry, in shade. No abrasive pads, strong solvents, or strong acid or alkaline cleaners. Test any other product on a hidden area first. The finisher's care instructions [attached] govern.

Standards and sources

• Euro Inox, Building Series Vol. 15, Cleaning Architectural Stainless Steel (2011)
• Euro Inox, Building Series Vol. 16, Colouring Stainless Steel (2011)
• BSSA SSAS 7.20, Care and Maintenance of Stainless Steel (issue 02, 2001)
• CCI Notes 9/3, Brass and Copper: Cleaning, Polishing, Waxing (2007): museum objects.
• AAMA 609 & 610-09, Cleaning and Maintenance of Finished Aluminum: US guide, revised 2009.
• A US hardware maker's finish care sheet: read 5 Nov 2026.

Questions we are asked

Can I use bleach on stainless steel?

No. Chlorine bleach and hydrochloric acid products cause staining and pitting, and the British Stainless Steel Association names splashes of undiluted bleach and mortar cleaners as a frequent cause. If any is spilt, Euro Inox says to rinse it off at once with plenty of fresh water.

How do I clean brass door handles in a hotel?

Find out first whether they are lacquered. Lacquered brass: soft cloth, mild soap and water, dry, and no brass polish unless you mean to strip the lacquer. Unlacquered brass: dust, mild detergent and water, dry, and accept that it will darken. Avoid ammonia polishes. A thin microcrystalline wax cuts how often it needs cleaning.

How do I clean PVD-coated handles?

Treat the coating as more delicate than the steel. Euro Inox advises low-pressure hosing with water and detergent, or a soft cloth or soft plastic brush, with no abrasive pads or compounds and no high-pressure jets. A damaged area cannot be repaired on site, so ask the coating house for its care sheet.

What damages powder-coated metal when it is cleaned?

Abrasive rubbing, which can change the texture or add shine, and strong solvents or cleaners, which can soften or mark the paint. AAMA recommends mild soap or detergent, rinsing and drying, and a test on a hidden area first.

What should cleaners avoid on anodised aluminium?

AAMA names trisodium phosphate and phosphoric, hydrochloric and hydrofluoric acids and fluorides, and warns that dried mortar and cement will corrode the coating. Use water and mild detergent, with a nylon pad along the grain for heavier soil.

How often should metal finishes be cleaned?

There is no single figure. The BSSA's rule is to clean when dirty, one to four times a year outside and daily in hygienic uses, with more attention in pool halls and by the coast. AAMA asks owners to take the schedule from the finish supplier. Put the frequency in the handover pack.

Can scratched stainless steel be repaired?

Light marks come out with a non-scratching cream, or a nylon pad worked along the grain on brushed finishes. For more, the BSSA notes that specialists can mechanically polish or electropolish stainless on site. Coloured and PVD stainless cannot be repaired on site: the panel is replaced.