TR-668 is a white-blue passivator built for zinc-plated workpieces. Parts leave the dip with a thin, translucent film that lets the brightness of the zinc underneath show through, so the finish reads as a clean white-blue rather than a coloured conversion coat. It is the economical member of our passivator family: the working bath tolerates the zinc and iron that parts carry in with them, holds its life over long production runs and keeps additive consumption low.
The chemistry is trivalent chromium from make-up to working bath, with no hexavalent chromium anywhere in the process. Where a decorative colour is needed — yellow, olive or black — another passivator in the range covers that job. This white-blue passivator is aimed at volume zinc work that needs a bright, neutral finish from a step that is easy to keep in control; it is not the grade used for passivation of stainless steel, which takes a separate acid process.
It is a straight immersion process run at ordinary shop temperature, which suits job shops running several short batches a day as well as in-house lines running one part family for weeks. If you are weighing it against a chromate process, the practical differences are the ones that show up on the line: no hexavalent chromium in the effluent, a bath that survives contamination better, and a film that stays clear rather than yellowing.
| Parameter | Value |
|---|---|
| Product type | White-blue trivalent chromium passivator |
| Application | Zinc plating, post-plating passivation |
| Operating condition | Operating range |
| Concentration | 40-70 ml/L (depends on passivation time) |
| Immersion time | 10-40 s (the higher the content, the less the passivation time) |
| Temperature | 20-30 °C |
| pH | 1.8-2.5 |
| Film appearance | Translucent white-blue over a bright zinc deposit |
| Chromium chemistry | Trivalent chromium; no hexavalent chromium |
| Brand | FENGFAN |
| Model | TR-668 |
| Place of origin | China |
The economical case for this passivator is really about bath life. A zinc passivation bath fills up with zinc dissolved off the parts and iron carried in on racks, barrels and poorly rinsed work. A bath that tolerates that load keeps producing a usable film far longer than a sensitive one, and needs fewer dumps, less make-up and less attention between shifts. In industrial electroplating the cost of a passivator is rarely the drum — it is the downtime spent replacing a bath in the middle of a production run.
Keep the working solution inside its band and it stays predictable. Titrate for concentration rather than topping up by eye, check pH after every shift change, and filter when the solution turns cloudy or when parts start coming out with spots. The bath has a long working life, but it is not endless: when the dip needed to reach the same tone keeps climbing, the contamination load has caught up and it is time to replace the solution.
Make up with clean water, keep the tank covered when the line is idle, and log concentration, pH and temperature at the same point in every shift. Three numbers on a sheet tell you more about a drifting bath than any single appearance check, and they make a clean handover to the next shift possible.
A white-blue finish is the workhorse of zinc passivation, which is why this bath turns up across a very wide spread of parts. Barrel lines running fasteners, stampings, spring washers and small turned parts use it because the dip is short and the film does not build heavily on edges. Rack lines running brackets, frames, welded assemblies and pressed housings use it because the translucent film leaves the zinc brightness intact and reads as a consistent light tone across a large surface. Shops serving automotive hardware use it where a chromate process is being phased out and the drawing still calls for a bright, neutral passivated finish. Builders' hardware, shelving and racking components, garden and outdoor fittings, and electrical enclosures all sit comfortably in the same range.
Because the film is thin and clear, it is unforgiving about what happens upstream. A part with a dull deposit, a burn at a contact point or visible polishing lines will still show all of it after passivation, so this is a finish that rewards a well-run zinc line rather than covering for a poorly run one. That is also why it fits so naturally into industrial metal plating work where several part families share a line and the operator needs one passivation setting that behaves the same way all week.
If your part is a decorative piece that depends on colour rather than brightness, a yellow, olive or black passivator will serve you better; the white-blue tone is deliberately neutral.
Passivation is the last metre of a long line, and it only performs if everything in front of it did. That is why we supply the whole sequence rather than a single dip: brighteners and additives for acid, alkaline and cyanide-free zinc systems; copper processes from non-cyanide alkaline through bright acid; nickel brighteners for rack, barrel and multilayer work; hard chrome and decorative chrome additives; and alloy processes such as zinc-nickel and tin-cobalt. Pretreatment chemicals — degreasers, derusters and phosphating agents — and post-treatment sealers sit at the two ends of the same sequence.
For industrial metal plating shops this means one technical contact for a whole line instead of several suppliers who each point at the other when a part fails. Tell us the substrate, the zinc system and the finish target, and we will tell you which passivator and which sealer belong together, and where in the rinse train the weak point usually is.
The same applies when a finish fails and nobody is sure which tank is responsible. Send the part, the process sequence and the test result, and the answer is usually found by working backwards from the last tank to the first — which is much faster when one supplier knows all of them.
A passivation film is only as even as the surface it forms on, and most surface defects begin in cleaning long before the part reaches the passivator. Our surfactant range covers the wetting agents, emulsifiers and low-foam cleaners used in alkaline degreasing and in acid systems, where the job is to lift polishing compound, drawing oil and fingerprint grease out of recesses without attacking the substrate. In industrial electroplating lines the same surfactants control foaming in agitated tanks and help rinse water sheet off the part instead of beading on it, which matters more than it sounds: a beading rinse leaves residue that shows up as a patchy passivation tone.
On the coating side we supply paint chemicals and coating additives used to tune adhesion, flow and surface finish, plus chemical intermediates for formulators who blend their own products. These are not side lines for us — they share the same batch control and documentation routine as the plating range, and they are often bought by the same shops.
If you are troubleshooting a film that will not form evenly, describe the cleaning stage as well as the passivation stage. In most cases the answer is in the rinse before the dip, not in the dip itself.
Wuhan Fengfan International Trade is the export arm of Wuhan Fengfan Electrochemical Technology, founded in 1984 and focused on the research and development of electroplating additives. Four decades in one field builds a particular kind of process knowledge: we have watched processes move from cyanide to alkaline, from hexavalent chromium to trivalent and from hand lines to automatic ones, and the product range reflects each of those transitions.
Today the catalogue covers general metal electroplating, electroless plating, electronic plating, aluminium anodizing chemicals, chemical intermediates, surfactants, coating chemicals, chemical raw materials and surface treatment equipment — the full span of industrial metal plating, from pretreatment through to the final sealer, including passivation of stainless steel and the zinc passivators described on this product. Each production batch is checked against its reference standard before packing, so a repeat order behaves like the first one.
Buyers come to us rather than to a catalogue because the questions that decide a job are process questions: which bath, at what strength, on which line, with which sealer. Those get answered by people who work with plating lines every day, before the order and after it.
Most lines that run this passivator buy the rest of the sequence from us as well. On the zinc side there is a brightener for SZ-30B sulfate zinc plating, ZN 50 bright zinc alkaline for rack and barrel plating, and ZN-500 brightener for cyanide-free alkaline zinc. For aluminium anodizing we supply the Phoenix EB 204A-204B divalent tin salt electrolytic colouring additive, Phoenix Seal 149-L middle temperature sealing agent for aluminium anodizing and Phoenix Seal 149-T medium temperature sealing agent. For copper work there is the FI-970 bright acid copper plating process, and for chrome lines the FF-116 environmentally friendly chrome mist inhibitor, alongside Nickel Purify P3 for nickel bath purification and FF-4219 nano-protective treatment for wood, stone and concrete.
Each of these plating solutions and treatment chemicals follows the same batch-control and documentation routine as this passivator, so a mixed order arrives with one consistent set of paperwork rather than several.
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 thin, translucent white-blue film that keeps the brightness of the zinc visible underneath. On a well-plated part it reads as a clean, slightly cool light tone with no yellow cast and no heavy iridescence. Because the film is thin and clear it does not cover polishing lines, contact marks or a dull deposit — those show through, so the finish is judged on the passivation step and the zinc underneath together. If you need a coloured film — yellow, olive or black — choose a different passivator from the range instead of pushing this one out of its range.
They are effectively one setting. Running the bath at the stronger end of the range builds the film in a shorter dip; running it leaner stretches the dip and gives more room to correct a line that tends to over-passivate. Start from the middle of both ranges on a trial part, change one variable at a time, and keep the accepted sample. In zinc plating passivation the most common cause of a drifting tone is not the bath itself but an immersion or transfer time that changes between shifts.
Not always, but it is the most direct way to lift salt-spray performance when a customer's specification is tight. A sealer applied after the final rinse adds a barrier layer over the passivated zinc, and the chrome-free sealers in our range are made to follow exactly this sequence. Most industrial electroplating shops keep one sealer available and specify it only for the parts that need it, since sealing also shifts the appearance slightly, usually towards a more silver tone. Confirm the sealer and its strength against your own salt-spray target before committing a production batch.
Yes. It is a straight immersion step, so it works on rack jigs and in barrels. What changes is drainage and transfer: a barrel that keeps turning in the drag-out zone is still being passivated, and a rack lifted slowly carries a longer contact time than one lifted quickly. Set the immersion time to include the transfer, and keep that routine identical across shifts so the tone does not drift with the operator.
Talk to us with the details and we will look at what is possible. Formulation and specification adjustments are part of what we do, and the useful starting point is your zinc system, the part family, whether you run rack or barrel, and the appearance or corrosion target you are working to. Some requests turn out to need a concentration or time change rather than a different product, so it is worth describing the problem before assuming a new formulation is needed.
At the end, after zinc plating and after the dilute nitric acid brightening dip, and before sealing and drying. It is a post-treatment rather than a plating step: no metal is deposited, the chemistry reacts with the zinc surface to form a passive film. Everything before it — degreasing, rinsing, the zinc deposit itself — sets the ceiling on what it can deliver, which is why a passivation problem is often really a rinse or plating problem.
Better than most, which is why the bath life is long. Zinc dissolved off the parts and iron carried in on racks and barrels are the normal load and the formulation tolerates both; heavy carry-over of plating solutions and rinse water is what pushes it. Reduce the load by rinsing properly before the dip, filter when the solution turns cloudy, and replace the bath when the dip time needed for the same tone keeps climbing.
