This bath deposits a tin plating alloy with cobalt and zinc on small parts that run loose in a barrel. The coating comes out bright and smooth, and on decorative work it is read as chromium, which is why it is normally chosen as a substitute for a chromium layer rather than as a wear coating.
It is bought mostly by shops running industrial metal plating lines that need chromium out of the building, either because a customer will no longer accept a chromium layer or because keeping a chromium tank for appearance-only parts no longer pays.
The plating chemicals are straightforward to handle, and the make-up follows the familiar order of metal plating techniques. Potassium pyrophosphate carries the bath, stannous chloride supplies the tin, cobalt chloride and zinc chloride set the alloy, and the additive and stabilizer finish the make-up. Nothing in that sequence needs equipment beyond a heated tank, agitation and a barrel line.
A chromium tank holds a hot bath and keeps it there all shift. This bath works at a lower temperature and needs only a modest current density for barrel work, so the power drawn per load sits well below a chromium plating process doing the same job. The saving usually shows on the energy bill before it shows anywhere else.
Stability matters more than the peak numbers. The bath is designed to hold its composition through a shift, so colour and coverage do not drift from barrel to barrel and a line can run long campaigns by topping up rather than remaking the tank. Compared with older metal plating techniques, that repeatability is what makes the process usable in continuous production, where an interruption costs more than the chemicals.
| Parameter | Value |
|---|---|
| Stannous chloride (SnCl2·H2O) | 20–30 g/L |
| Cobalt chloride (CoCl2) | 8–12 g/L |
| Zinc chloride (ZnCl2) | 5–10 g/L |
| Potassium pyrophosphate (K4P2O7) | 220–280 g/L |
| RC-90 additive | 20–30 mL/L |
| RC-90 stabilizer | 4–8 g/L |
| pH | 8.5–9.5 |
| Temperature | 20–45 °C |
| Cathode current density (Dk) | 0.1–2 A/dm² |
| Anode | Pure tin plate |
| Coating | Tin-cobalt-zinc alloy, chromium-like appearance |
| Line type | Barrel plating for small parts |
| Document | What it covers |
| Technical data sheet | Bath composition, operating window and the make-up sequence in one document |
| Safety data sheet (SDS) | Handling, storage and first-aid information for the neat chemicals; ask your sales contact for the current version |
| Composition statement | Confirms the coating is a tin plating alloy containing cobalt and zinc, with no chromium layer, and that the make-up contains no cyanide salt |
| Market documentation | Tell us the destination market and the declaration your customer asks for, and we confirm what can be issued for this product |
| Batch inspection certificate | Issued after delivery with the batch number and the warranty period of that lot |
| Traceability | The batch number on the certificate ties each drum or box back to the lot it was filled from |
One of the notable features of this additive is its lower energy consumption compared to chromium plating, which makes it efficient for large-scale application. The electrolyte is suited to barrel plating processes for small parts, improving production efficiency in mass manufacturing with fewer interruptions. Its reliable formulation allows repeatable results, creating a dependable foundation for operators handling plating chemicals in continuous production. It also integrates into finishing environments where electro nickel plating methods are applied, keeping lines stable while maintaining production quality.
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.
It does the finishing work rather than the plating itself. The salts supply the tin, cobalt and zinc; the additive controls how bright the deposit comes out and how evenly it covers the load, and the stabilizer keeps the solution from drifting. Take the additive out and the deposit goes dull and coverage in recesses drops.
Yes. Energy consumption is lower than a chromium plating process, mainly because the tank does not have to be held at chromium-plating temperature and the current density needed for barrel work is modest. The difference is small per part and adds up across a month of barrel work.
Yes. The bath is built for general barrel plating of small parts and runs as a separate line, so it can sit alongside zinc-nickel work without touching that chemistry. Load size and barrel rotation are set the way you already run them.
It is not plumbed into a nickel line and shares no chemistry with one. It has its own plating solution, its own tank and a tin anode, so in practice it goes into the same finishing area as a separate station.
Each one has a job. Potassium pyrophosphate carries the metal ions in solution, stannous chloride is the tin source, cobalt chloride and zinc chloride set the alloy ratio, and the additive and stabilizer control brightness, coverage and bath stability. Change one and the deposit changes with it.
Pure tin plate is the anode this bath is built around. In a tin-cobalt-zinc system the anode replaces only the tin that leaves the solution onto the work; cobalt and zinc are held through the make-up salts and routine additions, not through the anode. That makes the anode the control point for the tin side of the alloy. Substituting another material is not a neutral change: a tin-lead, zinc or inert anode shifts the deposit composition, the finish drifts toward duller or greyer tones, and corrosion behaviour moves with it.
Anode quality matters as much as anode type. Impurities such as lead, copper or iron dissolve into the bath and show up as roughness, dullness or poor coverage that no additive can correct, so ask us to confirm the anode specification that suits RC-90 before you load a new batch. In barrel work, arrange enough anode area around the barrel to carry the current without forcing the voltage up, and bag the anodes so sludge stays out of the plating solution. Check and clean the bags on a routine, keep the anodes immersed and active rather than letting them passivate, and top up tin salts when bath analysis calls for it instead of relying on anode area alone. If you are changing anode form — plate, bar or ball — for a different barrel, ask us to review the layout with you first.
Run one barrel load and compare it side by side with the part your metal plating service supplies today, under the same light. Then look at the recessed faces, because that is where the wider covering ability shows up first.
