The fast brightener for potassium chloride acid zinc plating is supplied as two components: a brightener that drives gloss and a base solution that supports the bath. Both are dosed into a conventional potassium chloride and zinc chloride electrolyte, so a shop already running acid zinc can change additive without rebuilding the tank, the anode set-up or the rinse line.
It suits job shops and in-house plating lines that finish steel parts on racks or in barrels and want a bright, level deposit that still takes a colour passivation afterwards. Typical work is fasteners, stampings, brackets and small machined components — the everyday output of a shop that buys acid zinc plating chemicals by the drum.
What the system is really bought for is speed and economy. Brightening develops quickly, so short barrel cycles finish glossy rather than half-bright, and the bath holds its gloss on small additions of brightener. The formulation also resists iron build-up, which is the usual reason an acid zinc bath loses its shine and starts rejecting passivation.
Because the electrolyte is a chloride system, there is no cyanide in the tank or in the rinse water, and the make-up salts are ordinary potassium chloride, zinc chloride and boric acid rather than a proprietary blend.
The two components are adjusted separately, which gives the line operator one lever for gloss and another for the body of the bath, instead of a single additive trying to do both jobs. Run the bath inside the working range and the plating process stays predictable from one shift to the next.
| Parameter | Rack plating | Barrel plating |
|---|---|---|
| KCl | 180~220 g/L | 200~240 g/L |
| ZnCl2 | 60~70 g/L | 40~55 g/L |
| H3BO3 | 30~35 g/L | 30~35 g/L |
| ZN-638 A brightener | 0.3~1 ml/L | 0.2~1 ml/L |
| ZN-638 B base solution | 15~25 ml/L | 15~25 ml/L |
| pH | 4.5~5.5 | 5.0~6.0 |
| Cathode current density (Dk) | 0.5~5 A/dm² | 0.2~3 A/dm² |
| S K : S A | 1:1.5~2 | 1:1.5~2 |
| Anode | 0# zinc ingot | 0# zinc ingot |
Dosing discipline. The brightener and the base solution are separate plating chemicals and behave differently in the tank. Component A goes in small measured additions; component B carries the bulk of the make-up. Log both against the amp-hours you run, because consumption per thousand amp-hours is the number that shows whether the bath is behaving or quietly drifting, and a rising trend usually supports drag-in or an anode problem rather than to the additive.
Iron is the main enemy. Acid zinc baths take in iron from pickling carry-over, steel racks, unplated parts and dusty shop air. Early signs are a slight loss of gloss at low current density, a cloudy solution, and a passivation film that comes out patchy or darker than usual. This system tolerates iron better than a basic brightener, so you get more running hours before quality drops — but tolerance is not immunity. Tighten rinsing after pickling, keep racks clean, and when the trend keeps climbing, treat the bath and filter it before the next batch rather than after a rejected load.
pH and anode condition. Check pH each shift and adjust with the same acid or base you use for your other electroplating chemicals, staying inside the working range for your line type. Keep 0# zinc ingots clean, bagged and free of sludge; a passivated or sludged anode changes current distribution and shows up as dull patches that no amount of brightener will fix.
Filtration and movement. Continuous filtration together with normal cathode or barrel movement keeps the bath uniform and stops particles plating into the deposit. If the fault looks like roughness rather than dullness, check the filters before touching the chemistry.
Keep the record. Note make-up concentrations, pH, temperature and current density for each batch. When a customer asks why one lot looked different from the last, that record is what lets you find the cause inside your own plating process instead of guessing at the bath.
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 is built around the potassium chloride acid zinc bath rather than adapted to it. Brightener and base solution are separate plating chemicals dosed into a KCl and zinc chloride electrolyte, so gloss and bath condition are adjusted independently, and the same pair runs on rack and barrel lines. Brightening is fast, which is what keeps short barrel cycles glossy, and replenishment is small, so the additive does not dominate the running cost of the bath.
Yes. The make-up in the table is a starting point, not a fixed recipe. Send your bath volume, line type, substrate and current density and we will confirm concentrations, pH and dosing for your tank. Because we work across a wide range of electroplating chemicals, we can also tell you how this brightener behaves alongside the passivation and sealing steps that follow the zinc deposit, and we will confirm in writing what can be adjusted for your order and what should stay as it is.
The system has a wide operating temperature range and a high cloud point, so the bath stays clear and keeps brightening in warm shops and through summer production — the conditions where a low-cloud-point brightener clouds and loses efficiency. Temperature and pH tend to drift together in hot weather, so check both and correct the pair rather than chasing pH alone, or the plating process drifts back out of range within a shift. Tell us the temperature your line actually reaches and we will confirm the window for your tank.
The gloss carries into the passivation step, and parts come out clean in multicolour, white-blue and white passivations. Colour evenness depends on the zinc being uniform before passivation, so keep current density inside the working range and rinse thoroughly between the zinc tank and the passivation bath. If your market restricts hexavalent chromium, ask us about trivalent passivation options before you lock the process in.
Start with a bath analysis: know your KCl, zinc chloride, boric acid and pH so the first make-up lands inside the working range rather than at one end of it. Look at the anode and the filtration too — a new additive will not fix a sludged anode or a dirty bath. Then plate a batch of your own parts and judge it on the finish you sell, not on a test panel. Metal plating shops that switch in one step usually see the difference in the first barrel load; if yours does not, the bath analysis is the first thing to review.
