Few topics ignite more passionate debate on a collectors' forum than brass cleaning. Post a photograph of a freshly polished 18-pounder shell case and watch the comments divide: half the room will admire the gleaming finish, the other half will mourn the century of honest patina that was scrubbed away in an afternoon. Both sides have a point — and that tension sits at the heart of everything we'll cover in this guide.
Whether you've just pulled a First World War cartridge case out of a Flanders field, picked up a set of Victorian tunic buttons at a militaria fair, or inherited a shelf of trench art from a grandparent, you're dealing with brass that has its own story written across its surface. Shell cases, cap badges, fuse bodies, shoulder titles, and trench art each present unique cleaning challenges — different alloys, different surface conditions, and different expectations from the collecting community about what "clean" should mean.
This guide is written by collectors, for collectors, drawing on decades of combined hands-on experience from the British Ordnance Collectors Network community. We cover both cosmetic cleaning — making items look presentable for display or sale — and conservation cleaning — stabilising items for long-term preservation. Crucially, we explain when each approach is appropriate, because choosing the wrong one can do lasting damage to an item's value and historical integrity.
Quick Reference: Cleaning Methods — Gentlest to Most Aggressive
1. Warm soapy water (safe first step for everything)
2. Lemon juice and bicarbonate of soda (light tarnish)
3. Vinegar and salt (moderate tarnish — monitor closely)
4. Commercial brass polishes — Brasso, Autosol, Peek (cosmetic polishing)
5. Citric acid solution (heavy tarnish, dug items)
6. Bar Keepers Friend (stubborn discolouration)
7. Mechanical cleaning — wire brushes, rotary tools, tumbling (most aggressive)
Always start at the top and work down. You can always escalate; you can never undo over-cleaning.
Before You Clean: The Golden Rules
Before you open a bottle of Brasso or reach for a wire brush, take a breath and consider these principles. Every experienced collector we know wishes they had understood these before they started.
"First, Do No Harm"
This is the single most important rule in the entire guide. Borrowed from the world of conservation, it means exactly what it says: you can always clean a little more next week, but you can never put back what you've removed. Approach every item with the assumption that less is more, and stop the moment you're satisfied — or slightly before.
Know What You Have
Military "brass" is not always straightforward 70/30 cartridge brass (70% copper, 30% zinc). Depending on the nation, era, and application, you may be handling gilding metal (a higher-copper alloy used for bullet jackets and some badges), phosphor bronze (common in fuse components), nickel-plated brass, or items with a factory-applied lacquer finish. German Second World War cartridge cases were often made from lacquered steel, not brass at all. Each material responds differently to cleaning methods, so take a moment to identify what you're actually working with before you begin.
The Patina Debate
We'll be upfront: the BOCN community holds a range of views on this. Some collectors — and many dealers — prefer bright, polished brass for display. There is nothing inherently wrong with this for common items.
However, most serious collectors and virtually all museums value honest age patina. That warm, dark golden tone on a First World War shell case isn't dirt — it's a stable oxide layer that took a century to develop. It tells a story. Removing patina can significantly reduce both the monetary value and the historical integrity of an item, particularly for scarce or unusual pieces. A rare Boer War headstamp that's been buffed to a mirror finish on a polishing wheel has lost something that cannot be restored.
Our advice: if you're unsure, leave the patina alone. You can always clean later. You cannot un-clean.
When NOT to Clean
Some items should not be cleaned at all, or should only be treated by a professional conservator:
- Items with original lacquer, paint, or factory-applied finishes — cleaning will destroy these.
- Items showing powdery, bright green spots that may indicate active bronze disease (chloride-driven corrosion) rather than stable patina — aggressive cleaning can spread the problem.
- Rare, high-value, or museum-quality items — the risk outweighs the reward. Consult a conservator.
- Items with original markings, labels, or unit stamps that could be worn away.
Document Before You Start
Before you touch a single cleaning product, photograph the item from multiple angles in good light. Record any markings, stamps, or features of interest. If something goes wrong — or if you later wish you'd stopped sooner — you'll have a permanent record of the item's pre-cleaning condition. This takes two minutes and can save real regret.
Understanding What's on Your Brass
Correctly diagnosing what's on the surface is half the battle. Here's what you're likely to encounter:
Tarnish is the dark brown or blackish discolouration that develops naturally as copper in the alloy reacts with oxygen and sulphur compounds in the air. It is stable, protective, and often considered desirable. Many collectors deliberately leave tarnish in place — it is not damage, it is age.
Verdigris is the green or blue-green deposit formed from copper carbonates or copper chlorides. Stable verdigris can be attractive and harmless. However, if the green deposits are powdery, bright, and seem to be growing or flaking, this may indicate bronze disease — an active, chloride-driven corrosion process that will continue to eat into the metal if left untreated. Bronze disease requires specialist intervention, not just a polish.
Dirt, mud, and soil deposits are extremely common on battlefield-recovered (dug) items. These are usually straightforward to remove but may be concealing damage or markings beneath.
Cosmoline, grease, and oil residues appear frequently on surplus military items that were stored in arsenals. These can be sticky and unpleasant but are generally simple to dissolve.
Lacquer is a clear or slightly tinted coating applied at the factory or by a previous owner. It was designed to protect the brass, and removing it is a deliberate decision — not something that should happen accidentally because you didn't realise it was there.
Paint and markings may be original and historically significant. Coloured bands, unit markings, and date stamps on shell cases can be far more valuable than a clean surface.
Corrosion and pitting represent actual metal loss beneath the surface. No amount of cleaning will repair pitting — you can only clean around it. Heavy cleaning of pitted brass often makes the damage look worse, not better.
Cleaning Methods — From Gentlest to Most Aggressive
Always begin with the gentlest method and escalate only if needed. We cannot stress this enough.
Warm Soapy Water
This is where every cleaning project should start — no exceptions. A basin of warm water with a small squirt of ordinary washing-up liquid (dish soap) and a soft-bristled brush (an old toothbrush works perfectly for smaller items) will remove surface dirt, grease, and loose deposits without any risk to the underlying brass.
For larger items like shell cases, a washing-up bowl or even the kitchen sink will do. Work the soapy water into recesses and around headstamps gently.
The critical step is drying. Brass that is left wet will develop new tarnish and water spots within hours. Rinse with clean water, then dry immediately and thoroughly with a soft cloth. A hairdryer on a low heat setting is ideal for driving moisture out of recesses, threads, and stamped markings.
Lemon Juice and Bicarbonate of Soda
This gentle, readily available home method works well for light tarnish. Mix the juice of half a lemon with a tablespoon of bicarbonate of soda (baking soda) to form a paste. Apply with a soft cloth, working in small circular motions. The mild citric acid dissolves light oxide layers while the bicarbonate provides a very gentle abrasive action.
Rinse thoroughly with clean water and dry immediately. This method is not aggressive enough for heavy tarnish or corrosion, but it's an excellent second step after washing if a bit more cleaning is needed.
Vinegar and Salt
White vinegar (acetic acid) combined with a teaspoon of table salt per cup of vinegar provides a more aggressive acid clean. You can soak small items for 10–15 minutes or apply the solution with a cloth for spot treatment.
Monitor closely. This combination works quickly and can over-strip brass if left too long, leaving the surface looking unnaturally pink or dull. Check the item every few minutes during a soak. Rinse thoroughly and dry immediately once you've reached the desired result. We'd recommend this for common items only — not for anything scarce or valuable.
Commercial Brass Polishes
This is where most collectors end up for cosmetic cleaning, and there are several reliable products worth knowing about.
Brasso is the classic household brass polish and the name most people think of first. It works well for achieving a bright finish, but it's important to understand that Brasso is mildly abrasive — each application removes a microscopic layer of brass along with the tarnish. For a common shell case destined for the mantlepiece, this is perfectly acceptable. It is not suitable for items where you want to preserve patina, fine detail, or original surface finish. Apply with a soft cloth, work in sections, and buff off before it dries hard.
Brasso Metal Polish — UK: https://amzn.to/4cOsQPT | US: https://amzn.to/3MPEfED
Autosol Metal Polish is widely used by collectors who want a finer, less aggressive finish than Brasso provides. Originally designed for chrome and aluminium, it works beautifully on brass and leaves an excellent shine with less abrasive action. A little goes a long way.
Autosol Metal Polish — UK: https://amzn.to/4qRUmiR | US: https://amzn.to/4kY8GVV
Peek Polish is a wadding-based polish — you tear off a small piece of impregnated cotton wadding and rub it directly onto the brass. It's convenient, effective, and well-regarded among collectors for smaller items like badges and buttons. The wadding format makes it easy to work into fine details.
Peek Polish — UK: https://amzn.to/4qZ34fn | US: https://amzn.to/46Ue728
Bar Keepers Friend is an oxalic acid-based powder cleanser that's effective for tougher cleaning jobs where standard polishes aren't cutting through. Make a paste with a little water and apply with a soft cloth. It's more aggressive than Brasso, so use it with care and don't leave it on the surface for extended periods.
Bar Keepers Friend — UK: https://amzn.to/4kUrl4T | US: https://amzn.to/4rFKTMX
A note on Renaissance Micro-Crystalline Wax Polish: this appears in many cleaning discussions, but it's important to clarify that Renaissance Wax is not a cleaner — it's a protective sealant. Developed from a formula created by the British Museum, it is considered the gold standard for post-cleaning protection by museums and conservators worldwide. We'll cover its use in the protection section below.
Renaissance Micro-Crystalline Wax Polish — UK: https://amzn.to/4b5XoeJ | US: https://amzn.to/40wh31e
Citric Acid Solution
This is a favourite among experienced military collectors, particularly for cleaning heavily tarnished or dug shell cases and cartridge cases. Food-grade citric acid powder is inexpensive, widely available, and highly effective.
Citric Acid Powder (Food Grade) — UK: https://amzn.to/4svHa4H | US: https://amzn.to/46UesBW
To prepare a solution, dissolve approximately 2–3 tablespoons of citric acid powder per litre of warm (not boiling) water. For a large shell case, you may need a bucket or length of plastic drainpipe sealed at the bottom. Submerge the item and check progress every 15–30 minutes. Light tarnish may clear in under an hour; heavily encrusted dug items may need several hours or an overnight soak.
The acid works by dissolving the copper oxide and carbonate layers. Once you're satisfied, remove the item, rinse thoroughly under clean running water, and dry immediately — again, a hairdryer is your friend here.
Cautions: Citric acid will attack soft solder, so avoid prolonged soaking of items with soldered joints (some badge fittings, composite fuse assemblies). It can also slightly etch the surface if the solution is too concentrated or the soak too long, so check regularly rather than walking away and forgetting about it.
Electrolysis
We include this method because collectors frequently ask about it, having seen impressive results on iron and steel items. Electrolytic cleaning uses a low-voltage DC power supply, a solution of washing soda (sodium carbonate) in water, and a sacrificial anode (typically a piece of mild steel) to drive corrosion products off the item being cleaned.
However, electrolysis is primarily designed for ferrous metals and is not generally recommended for brass. On copper alloys, it can strip the surface colour unevenly, deposit copper or other metals from the solution in unwanted places, and leave a dull, unnatural appearance. If you're cleaning a steel helmet or an iron cannonball, electrolysis can be excellent. For brass, stick to the chemical and mechanical methods described elsewhere in this guide.
Mechanical Cleaning
When chemical methods alone aren't sufficient, mechanical cleaning provides more aggressive options — but these carry the greatest risk of damage if used carelessly.
Brass wire brushes are useful for scrubbing stubborn deposits off robust items like shell cases. Always use a brush with brass bristles (not steel), as steel will scratch and contaminate the brass surface. Work with the grain of any machining marks where possible.
Brass Wire Brush Set — UK: https://amzn.to/3OzC6O0 | US: https://amzn.to/4l0McUg
Steel wool should only ever be used in the finest grade — 0000 (four-zero). Anything coarser will leave visible scratches. Even 0000 grade removes material, so use it sparingly and with a light touch.
0000 Steel Wool — UK: https://amzn.to/4qVk3iq | US: https://amzn.to/3MuZDit
Rotary tools such as a Dremel fitted with brass wire wheels or cotton polishing mops can produce excellent results on trench art and shell cases, but they require practice. It's very easy to create uneven patches, remove fine detail, or generate excessive heat in one spot. If you've never used a rotary tool on brass before, practise on a worthless item first.
Tumbling is popular among cartridge collectors and reloaders for cleaning large batches of small arms cartridge cases. A vibratory tumbler loaded with stainless steel tumbling pins and a small amount of water and washing-up liquid will clean cases to a bright finish in 1–3 hours. Ceramic or walnut-shell media are also used.
Vibratory Tumbler — UK: https://amzn.to/4rvHCzy | US: https://amzn.to/3OzCMmw
Stainless Steel Tumbling Pins — UK: https://amzn.to/40wifSg | US: https://amzn.to/4r7atte
A word of caution on tumbling: the pins and media work by physically abrading the surface, and prolonged tumbling will round off sharp edges, soften headstamp impressions, and wear down fine markings. For common, fired cartridge cases destined for a display board, this is a non-issue. For anything scarce, unusual, or where the headstamp detail matters, tumbling is not appropriate. Check cases frequently and remove them as soon as they're clean enough.
Specific Guidance by Item Type
Artillery Shell Cases and Cartridge Cases
These large, robust items are the most forgiving to clean and the most common brass militaria in collections. For lightly tarnished examples, warm soapy water followed by Autosol or Brasso will produce a fine display piece. For heavily tarnished or dug items, a citric acid soak is usually the most effective approach.
Should you clean the inside? For display purposes, it's usually unnecessary — nobody sees the interior. However, if the case is damp or has soil packed inside, you should clean it out to prevent ongoing corrosion. Rinse thoroughly and ensure the interior is completely dry before storage.
For very large items (e.g., 4.5-inch, 25-pounder, or larger cases), a length of plastic waste pipe sealed at one end with a rubber cap makes a practical soaking vessel for citric acid treatment.
Small Arms Cartridge Cases
Headstamp preservation is paramount. The headstamp — the markings on the base of the case showing manufacturer, date, and calibre — is the single most important feature for collectors. Any cleaning method that risks wearing down these impressions should be avoided on uncommon examples.
Warm soapy water and a gentle hand-polish with Autosol or Peek is usually sufficient. Tumbling is fine for common cases but should be limited to short runs with frequent checking. Never tumble scarce headstamps.
Cap Badges, Buttons, and Shoulder Titles
These items are often delicate, with fine cast or stamped detail that aggressive cleaning will destroy. Many have backing plates, slider fittings, or lug attachments made from a different metal (often a softer alloy or tin) and secured with soft solder that acid solutions and prolonged soaking can weaken or dissolve.
Our recommendation for badges and buttons: warm soapy water to remove dirt, followed by careful spot-treatment with Peek wadding polish. Work the polish gently into recesses with a soft cloth or cotton bud. Avoid soaking, avoid abrasive brushes, and avoid anything that might stress solder joints.
Trench Art
Trench art is enormously varied — from simple engraved shell cases to elaborate pieces with applied brass, copper, aluminium, and even beadwork or painted decoration. There is no single cleaning method that suits all trench art.
The guiding principle is to identify all the materials present before cleaning anything. A shell case with a painted regimental badge and applied copper oak leaves contains at least three materials that will respond differently to any cleaning agent. When in doubt, stick to warm soapy water and a very gentle hand polish on the brass areas only.
Fuse and Projectile Components
These items frequently combine brass with other metals — steel, aluminium, zinc, copper — within a single assembly. Where dissimilar metals are in contact, galvanic corrosion may be at work, and aggressive chemical cleaning can accelerate this process. Disassemble components where possible before cleaning, and treat each material appropriately.
Ordnance safety applies especially here — see the Safety section below.
After Cleaning: Protection and Storage
Cleaning is only half the job. Unprotected brass will begin to tarnish again within days, particularly in humid environments. Proper post-cleaning protection is essential.
Drying
We've said it throughout this guide, but it bears repeating: dry your items immediately and thoroughly after any wet cleaning process. A soft cotton cloth followed by a hairdryer on low heat is the standard approach. Pay particular attention to recesses, threads, and stamped markings where water can pool. Some collectors place freshly cleaned items in a warm airing cupboard for an hour to drive off residual moisture.
Waxing
Renaissance Micro-Crystalline Wax Polish is the product of choice for long-term protection. Developed from a formulation by the British Museum's conservation department, it provides a stable, non-yellowing, breathable protective layer that is trusted by museums worldwide.
Apply a very thin layer with a soft cloth or brush, allow it to haze for a few minutes, then buff gently to a soft sheen. Thin coats are better than thick — a heavy application will look cloudy and attract dust. One coat is usually sufficient for display items; two coats provide additional protection for items in less controlled environments.
Renaissance Micro-Crystalline Wax Polish — UK: https://amzn.to/4b5XoeJ | US: https://amzn.to/40wh31e
Lacquering
Some collectors apply a clear lacquer spray to maintain a bright finish without ongoing polishing. Modern brass lacquers work reasonably well in the short term, but they have drawbacks: they tend to yellow with age, they can peel or crack, and they are difficult to remove cleanly once they've degraded. For these reasons, most experienced collectors in the BOCN community prefer wax over lacquer.
Storage
How you store your collection matters as much as how you clean it. Avoid sealed plastic bags, which trap moisture and create a microclimate that accelerates tarnishing. Instead, wrap items in acid-free tissue paper and store in a dry, stable environment.
Acid-Free Tissue Paper — UK: https://amzn.to/4c8G0XM | US: https://amzn.to/3P0zDvU
Silica gel sachets placed in display cabinets and storage boxes help control humidity. Replace or regenerate them periodically — most can be dried out in a warm oven and reused.
Silica Gel Sachets — UK: https://amzn.to/40v8pjC | US: https://amzn.to/4b8Kz3c
Handle waxed items with clean, dry hands — or better yet, wear cotton gloves for display pieces. Fingerprint oils are acidic and will etch through wax over time, leaving permanent marks.
Safety
Brass cleaning involves chemicals, sharp tools, and — in our particular hobby — items with a military history that demands extra caution.
Ventilation. Always work in a well-ventilated area when using polishes, acid solutions, or solvents. Brasso and similar products produce fumes that should not be inhaled in quantity. If working indoors, open a window or use an extractor fan.
Gloves. Wear nitrile gloves when working with chemicals to protect your skin, and when handling freshly cleaned brass to prevent fingerprint oils from marking the surface.
Nitrile Gloves — UK: https://amzn.to/4qXfSCO | US: https://amzn.to/3OI9X7d
Eye protection. Wear safety glasses when using rotary tools (wire wheels can throw fragments) and when working with acid solutions, which can splash.
Safety Glasses — UK: https://amzn.to/46Uipqg | US: https://amzn.to/4rHv2NO
[H3]Ordnance Safety — Please Read This Carefully[/H3]
This section applies specifically to our community of military collectors, and it is not optional.
Some items in collections may still contain live propellant, explosive residue, detonators, or primers. This is particularly true of battlefield-recovered items, undeactivated ammunition components, and fuse assemblies. Never attempt to clean the interior of any item you are not 100% certain has been properly and professionally deactivated.
If you acquire an item and have any doubt about whether it is inert, do not attempt to disassemble, heat, soak, or mechanically clean it. Contact your local police or military Explosive Ordnance Disposal (EOD) unit for advice. This is not an overreaction — it is standard practice among responsible collectors, and the relevant authorities are accustomed to receiving such enquiries.
Toxic residues are also a concern. Military items — particularly small arms cartridge cases, primers, and anything associated with propellants or detonators — may carry residues of lead styphnate, mercury fulminate, lead azide, or other hazardous compounds. Always wash your hands thoroughly with soap and water after handling military items, and avoid eating, drinking, or touching your face during cleaning sessions.
Frequently Asked Questions
Can I use Coca-Cola to clean brass?
Yes, it does work — the phosphoric acid in Coca-Cola will dissolve light tarnish. However, the sugar content leaves a sticky residue that requires thorough washing afterwards, and the acid concentration is quite low, making it slow and inefficient compared to purpose-made solutions. Citric acid does the same job faster, more cleanly, and far more cheaply. We'd keep the Coke for drinking.
Should I clean dug items or leave them as-found?
This depends entirely on your intent. If you want to display the item and appreciate its appearance, cleaning is perfectly reasonable for common items. If you're a detectorist recording a battlefield find, or if the item is unusual and may benefit from professional examination, leaving it as-found (after gentle washing to remove soil) is the safer choice. Soil deposits can contain chlorides that drive ongoing corrosion, so at minimum, a wash in distilled water is advisable for long-term storage.
My brass has turned pink or salmon-coloured after cleaning — what happened?
This is dezincification — a common issue that occurs when an acidic cleaning solution (vinegar, citric acid, or even lemon juice) selectively dissolves the zinc from the brass alloy, leaving behind a layer of porous, copper-rich metal with a characteristic pinkish or salmon hue. It's caused by using a solution that's too strong, soaking for too long, or both. To avoid it, use weaker solutions, check items frequently during soaking, and rinse promptly. Once dezincification has occurred, it cannot be reversed — the zinc is gone — but a gentle polish with Autosol can improve the appearance somewhat.
Is it safe to use brass cleaner on items with stamps or markings?
Liquid and paste polishes applied with a soft cloth are generally safe for stamped or roll-engraved markings (headstamps, broad arrows, manufacturer marks), as the polish works primarily on the raised surface and tends not to reach into the recesses of the impressions — in fact, leaving polish residue in the recesses can actually enhance legibility by providing contrast. The methods to avoid are mechanical ones — tumbling, rotary tools, and abrasive pads — which physically wear down the edges of stamped markings over time.
How do I remove green corrosion without damaging the brass?
First, determine whether you're looking at stable verdigris (a copper carbonate patina that is dry, hard, and not actively growing) or active bronze disease (powdery, bright green copper chlorides that are spreading). Stable verdigris can be left in place — many collectors consider it attractive — or gently reduced with a citric acid solution if you prefer a cleaner look. Active bronze disease requires treatment with a solution of benzotriazole (BTA) to stabilise the chlorides, followed by thorough rinsing and waxing. If you suspect bronze disease, seek advice from a conservator or post photographs on the BOCN forum — the community has considerable experience identifying and treating this condition.
Conclusion
If there's one message we hope you take away from this guide, it's this: less is more. The best cleaning job is one where you've removed just enough to stabilise and present the item, while preserving as much of its original character as possible. A shell case with a warm, even patina and clearly legible markings will always be more impressive in a serious collection than one that's been buffed to a featureless mirror shine.
Every item is different, and there's no shame in asking for advice before you start. The BOCN forum exists precisely for this purpose — post photographs, describe what you have, and the community will help you decide on the best approach. Between us, we've cleaned (and occasionally over-cleaned) just about everything, and we're always happy to share what we've learned.
If you're not already a member, we'd encourage you to join the British Ordnance Collectors Network at www.bocn.co.uk — it costs nothing, and you'll find a community of knowledgeable, welcoming collectors who share your passion for preserving military history.
Good luck with your cleaning — and remember: when in doubt, stop.
This article reflects the collective experience of the BOCN community and is provided for informational purposes. Always exercise caution and personal judgement when cleaning collectible items. Neither BOCN nor the author accepts liability for damage to items resulting from cleaning. This article contains Amazon affiliate links — purchases made through these links help support the BOCN website at no additional cost to you.
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