Gun-color — the dark, faintly blue-black tone the trade also calls black pearl — is one of the few decorative finishes that still looks intentional after a few years of handling. It is produced here by a tin-nickel alloy layer deposited directly onto bright nickel plating, so the colour is part of the coating itself rather than a dye, a lacquer or a post-dip that can rub away at the edges.
Because the layer is an alloy and not a thin film, appearance arrives together with hardness. Buckles, clasps, bezels and trim rings that knock against other components in service keep their tone instead of polishing back to the metal underneath, and parts that are merely looked at hold a deep, even colour without the iridescent patchiness that dyed finishes develop.
The bath is a potassium pyrophosphate system run at pH 8.5–9.5 and 40–45 °C with graphite anodes, and it holds its colour well enough to be practical on both rack and barrel lines from the same chemistry. We supply the complete set — Powder A, Agent B and stabilizer — together with the make-up order and the chromic acid passivation that follows plating, so a shop adding gun-color to its nickel plating services starts with a full recipe instead of a single bottle of additive and a guess.
| Product type | Tin-nickel (Sn-Ni) alloy plating chemical |
| Brand | Fengfan |
| Potassium pyrophosphate (K4P2O7) | 200~250g/L |
| "Gun-color" Powder A | 25–30 g/L |
| "Gun-color" Agent B | 35–40 g/L |
| "Gun-color" Stabilizer | 1–2 g/L |
| pH | 8.5~9.5 |
| Temperature | 40–45 °C |
| Anode | Graphite |
| Cathode current density (Dk) | 0.1–2 A/dm² |
| Cathode replacement | Required |
| Passivation after plating | Chromic acid 50 g/L, room temperature, 20–30 s |
This is one of our coating production chemicals, built to sit inside a decorative line rather than beside it. The electrolyte is potassium pyrophosphate at 200–250 g/L, a chemistry many shops already handle for tin and tin alloy work, and the additive package is dosed in three separate parts so each one can be corrected on its own: Powder A at 25–30 g/L as the main component, Agent B at 35–40 g/L, and the stabilizer at 1–2 g/L.
None of that calls for a dedicated line. Where a tank already lays down a bright nickel underlayer, the black nickel plating step goes on after it and before passivation — graphite anodes replace soluble metal anodes, the tank is heated to 40–45 °C, and pH is checked in the 8.5–9.5 band. Existing racking, barrels, rectifiers and rinse trains carry over.
The recipe also scales without conversion. Because every concentration is expressed per litre, a small trial tank and a full production tank are made up to the same figures, and the same dosing discipline carries from one to the other. For an industrial metal plating operation introducing a gun-color finish, that is what keeps the first production batch comparable with the sample that was signed off.
Decorative parts are almost always rejected on appearance before they are rejected on anything mechanical, and appearance is the first thing a drifting bath changes. Holding temperature, pH and the additive balance inside the stated window is therefore the biggest single lever a shop has on yield, and it costs nothing except attention.
The practical benefit is fewer strip-and-replate cycles. A part that has to be stripped and run again consumes plating time twice and loads the bath with the extra work; a bath that repeats its colour removes most of that traffic, and the line supervisor stops re-checking colour every hour.
The three-part dosing helps when the tone does move, because you correct one component instead of guessing at a blended brightener. Graphite anodes take anode corrosion out of the maintenance routine, and the additive concentrations are given per litre, so a correction can be calculated rather than estimated.
Across an industrial metal plating line the savings rarely show up in one dramatic place. They accumulate in fewer rejects, less rework, steadier throughput and a finish that can be quoted with confidence. For a metal plating service taking repeat orders on the same hardware, colour consistency is the difference between a reorder and a complaint, and that is the result this chemistry is designed to produce. Our technical team can review your bath data and suggest where to look first if the colour does drift.
Ornamental work is judged harshly, because the part is small and the eye is close to it. A watch case shows its colour on a narrow bezel, a lamp trim sits against a plain shade, a buckle rests in the hand. A gun-color that goes patchy, or shifts toward brown across a curve, is obvious immediately — which is why the alloy layer rather than a dyed film is the sensible choice for these parts.
Working over bright nickel plating also gives a designer a way to combine finishes on a single product: polished nickel on one surface, black pearl on another, both produced on the same line with the same racking. Leather decorations use the same idea, where a bright frame plus black nickel plating on the hardware reads as a considered design rather than a mixed finish.
And because the colour repeats from batch to batch, a brand can carry one tone across a whole collection instead of one season of it. That is the quiet commercial argument for a stable bath: the finish becomes something a customer can reorder by name, not something that has to be re-approved every time.
This bath suits shops that do not run one product all week. Decorative work arrives in batches — a rack of watch cases, a barrel of fittings, a mixed order of hardware — and a process that holds its colour across those swings spares the operator from re-tuning between jobs.
Because rack and barrel plating share the same chemistry, changing line type is a loading decision rather than a bath change. A shop that normally barrel-plates small parts can hang a rack of larger components in the same tank, run them, and return to the barrel without a make-up or a dump.
The same flexibility extends to how work is booked. Semi-continuous decorative runs, short trial batches and repeat orders can all be planned against one operating window, because the constraint is temperature and pH discipline rather than batch size. For a shop serving several clients from a single tank, that is what lets black nickel plating be offered as a standard finish instead of a special.
We supply the components as coating production chemicals to a consistent specification, so a bath made up later in the year is made up to the same figures as the first one — which is what makes a repeat order a routine job rather than a re-development project.
| Payment | 100% T/T in advance |
| Minimum order quantity | Varies by chemical; confirmed with our sales team per order |
| Lead time | 2 weeks |
| Packing | 10 kg/box; 25 kg or 50 kg/bag; 20 kg/25 kg/30 kg/200 kg/drum; 1000 kg/IBC drum |
| Shipping | Per the terms agreed in the current contract |
| Warranty | Inspection certificate issued after delivery stating the batch number and warranty period |
Choosing the right match is where most sourcing decisions stall. As a trading supplier, we keep one point of contact from first enquiry to after-sales: tell us what you are making and the conditions you work under, and we shortlist the closest matches from our supplier network, compare specifications and arrange samples before you commit to a bulk order. If something does not behave as expected, we work with the supplying partner on the cause and a practical fix, and stay with the case until it is settled. Email, WeChat or WhatsApp enquiries get a reply within 24 hours.
A dark gun-color that the trade also calls black pearl — faintly blue-black, even in tone, and noticeably harder than a dyed or lacquered surface. The colour is created by the tin-nickel alloy layer itself, sitting directly on the bright nickel, so it does not wear out of the surface the way a coating can. It is normally the last decorative layer before passivation.
Potassium pyrophosphate 200–250 g/L, "Gun-color" Powder A 25–30 g/L, "Gun-color" Agent B 35–40 g/L and stabilizer 1–2 g/L, at pH 8.5–9.5 and 40–45 °C, with graphite anodes and a cathode current density of 0.1–2 A/dm². Keep temperature and pH inside those windows and the colour stays consistent; drift outside them and the tone is usually the first thing in the metal plating process to show it.
Yes. The same bath serves rack plating and barrel plating, so a shop that plates watch cases individually and small fittings in bulk does not need two solutions. Rack work lets you control which face is presented to the anode; barrel work gives you volume. The working window is 0.1–2 A/dm², so how you space the rack or load the barrel has more influence on the result than raising the current.
Yes, and small runs are where the finish usually proves itself. Watches, lamp fittings and leather hardware are plated in modest volumes, and the bath works at trial scale as well as production scale because every concentration is given per litre — a small tank takes the same figures as a full one. For a first run, plate a few panels or a single rack and check the black nickel tone against your approved sample before committing a batch.
If your line already lays down a bright nickel underlayer, this alloy goes on top of it without new equipment: a pyrophosphate tank, graphite anodes, heating to 40–45 °C and pH control between 8.5 and 9.5. What changes is the dosing — Powder A, Agent B and the stabilizer are added separately, so the bath is managed through the additive balance rather than through a dissolving anode. Whether you run a job shop offering nickel plating services or an in-house line, the practical check is a trial rack before a full tank is converted.
Hold the three variables that move first: temperature, pH and the additive balance. Replenish Agent B and the stabilizer as the bath is worked, keep the graphite anodes clean and correctly spaced, and set the current density against the 0.1–2 A/dm² window for the actual load. When colour moves, it is nearly always a bath condition moving rather than the salt failing.
The process data includes a passivation step straight after black nickel plating — chromic acid at 50 g/L, room temperature, 20–30 seconds. Whether anything further is required depends on the specification your customer is working to, so tell us the end use and we will confirm how the finishing sequence should look for that part.
Yes. This is a tin-nickel alloy process, so the deposit contains nickel, and that matters if the part is worn against skin or falls under a restricted-materials specification in your market. Raise it at enquiry and we will tell you honestly whether this finish suits the application or whether a different decorative process is the better route for that product.
The condition of the nickel underlayer on your sample parts, the tank volume and its heating capacity to reach 40–45 °C, a graphite anode supply, means to measure Powder A, Agent B and the stabilizer accurately, and a reference sample of the tone you want. Send us those details with your trial result and we can tell you which bath variable to adjust first. Trial availability and current lead time are confirmed by your sales contact.
