ZN-658 is a two-component additive set for potassium chloride acid zinc plating: one brightener, one make-up agent, dosed separately into the same bath. It is the economical option in the acid zinc range, built for shops that want a bright, fine-grained zinc deposit without a large brightener bill at the end of every shift. Rack work and barrel work both run on the same pair, so a job shop does not have to hold two additive systems for two line types.
The behaviour on the floor is straightforward. The coating comes out fine and bright with a high level of gloss and smoothness. The brightener is consumed slowly. The bath holds a wide temperature range and a high cloud point, so it keeps working in a warm plating shop without refrigeration and adapts to high-temperature production. Those three things together — gloss, low consumption, temperature tolerance — are what make these acid zinc plating chemicals economical rather than merely inexpensive.
Because the two components are separate, the zinc plating brightener level and the bath balance can be moved independently. That matters when the work mix changes: a run of small barrel parts and a run of large racked fabrications rarely want the same brightness, and a single-component additive forces a compromise between them. Keeping the pair in balance also keeps the deposit consistent from the first rack of the week to the last.
| Parameter | Rack plating | Barrel plating |
|---|---|---|
| Zinc chloride (ZnCl2) | 60-70 g/L | 45-60 g/L |
| Potassium chloride (KCl) | 180-220 g/L | 200-240 g/L |
| Boric acid (H3BO3) | 25-35 g/L | 25-35 g/L |
| pH | 4.5-6.0 | 5.0-6.0 |
| Temperature | 10-40 °C | 10-40 °C |
| Cathode current density | 0.5-5 A/dm² | 0.3-3 A/dm² |
| Anode | 0# zinc plate | 0# zinc plate |
| ZN-658A brightener | 0.5-1.5 ml/L | 0.5-1.5 ml/L |
| ZN-658B make-up agent | 20-30 ml/L | 20-30 ml/L |
The deposit is fine-grained and bright, with the gloss and smoothness that make a zinc coating look finished rather than merely protective. That brightness carries downstream: a passivation film takes its colour from the zinc underneath, so a clean bright base gives a more even blue-white, white or colour film, and a sealer applied afterwards has a better surface to build on.
Corrosion performance is a property of the whole stack, not of the brightener alone. Coating thickness, the passivation type, the sealer and the steel underneath all move a salt-spray result, and published hours are only comparable when those conditions match. If you need a figure for a customer, tell us the part, the coating weight and the passivation you intend to run, and we will tell you what data we hold for that combination rather than quote a number that belongs to someone else's line.
The same logic applies to how the plating chemicals are matched. A brightener that suits one passivation system can look wrong on another, and the sealer that lifts a salt-spray result is chosen against the passivation, not against the zinc. Within the metal plating process these decisions sit next to each other, which is why they are worth settling before the first production rack rather than after the first reject.
Acid chloride zinc baths are robust, but they are not self-cleaning. Iron is the contaminant that decides bath life: it arrives on pickled work and on work that was rinsed poorly, it is not consumed by the plating reaction, and it builds until the deposit dulls, the passivation discolours or the bath turns cloudy. Continuous filtration, well-bagged zinc anodes and a proper rinse after pickling all slow that build-up. If iron, copper or organic contamination has already taken hold, an acid zinc purifier can be dosed to pull it out of the bath; describe what you are seeing and we will point you to the right one.
Check pH daily and keep it inside the window for the mode you are running. A bath that drifts low plates dull and dark; one that drifts high loses throwing power and starts to precipitate zinc salts. Analyse zinc metal, chloride and boric acid on a fixed schedule rather than when something looks wrong — a routine analysis catches a drifting plating process while it can still be corrected with a top-up instead of a rebuild.
The equipment is ordinary for an acid chloride line but should still be specified: PVC, PP or rubber-lined steel for tanks and drip trays, fume extraction at the tank edge, acid-resistant racks and barrels, and a filter sized for continuous running. Water quality counts too; hardness and chloride in the make-up water shift the bath balance, so use clean or deionised water where you have it. None of this is exotic, but it is what decides whether a package of plating chemicals performs to its data sheet month after month.
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.
Yes, but not with the same bath recipe. Barrel plating runs a different zinc chloride and potassium chloride level with a slightly higher pH, so the two modes are set up differently even though they use the same two components. Shops that run both either keep a dedicated bath per mode or set the bath for whichever mode dominates and adjust for the other. These potassium chloride zinc plating chemicals are supplied as the same pair for either case.
Start with the zinc plating brightener. Small additions recover gloss quickly, and it is better to add in two steps and look at a panel than to dose once and overshoot. The make-up component is not a brightener — adding more of it will not bring the gloss back and will push the bath out of balance. If gloss does not return after a brightener addition, check pH, temperature and iron contamination before adding anything else.
No chiller is required to keep the bath inside its operating window. The wide temperature range and the high cloud point are why this process suits shops where the tank warms through the day and why it adapts to high-temperature production without extra cooling equipment. The metal plating process stays stable across that band; what the temperature does not change is the need to hold pH and the additive balance where the operating data puts them.
Yes. Rinse, neutralise and passivate as usual, then seal and dry. The fine, bright zinc layer gives passivation a clean base, so blue-white, white and colour films come out even. Match the passivation and the sealer to the corrosion target rather than to habit — a sealer usually moves a salt-spray result more than a heavier zinc layer alone. Passivation and sealing are separate steps from these potassium chloride zinc plating chemicals and should be judged on their own data.
Know the substrate and its surface condition, the tank lining and fume extraction you have, the water you will use, and how you will analyse zinc, chloride, boric acid and pH. Send us the line details and we will confirm make-up quantities and whether the rack or the barrel recipe fits your work. Ask for the SDS and the technical data sheet for your market at the same time, so the handling, storage and transport notes for these plating chemicals are on hand from the first drum.
