TR-290LC is our blue-working trivalent chromium passivator, the last wet step in the process of electroplating on an industrial metal plating line before the parts are dried and packed. Zinc-plated steel goes in after the bright dip and comes out with a thin chromium conversion film over the zinc — enough to hold back white rust, and enough to give the part a clean, bright blue-white appearance instead of the dull grey of an untreated deposit.
The bath is built for mixed shops. It passivates both acid zinc and alkaline zinc deposits, runs at room temperature, and behaves the same whether the work is racked, barrelled or dipped by hand on a manual line. A shop running two zinc chemistries can keep one passivation tank rather than two, and a shop that moves between rack and barrel work does not have to relearn the bath each time.
There is no hexavalent chromium in the make-up. What most buyers notice first is the colour: a bright, slightly translucent blue-white rather than a heavy iridescent film, which is why the grade is chosen for visible hardware as often as for plain corrosion protection.
| Property | Value |
|---|---|
| Product type | White-blue trivalent chromium passivator used in the metal plating process |
| Model | TR-290LC |
| Brand | FENGFAN |
| Place of origin | China |
| Deposit | Zinc-plated steel, acid and alkaline zinc |
| Concentration, optimum | 40 ml/L |
| Concentration, working range | 30-60 ml/L |
| Immersion time, optimum | 35 s |
| Immersion time, working range | 25-45 s |
| Bath temperature | Room temperature, 25 °C |
| pH, optimum | 2.5 |
| pH, working range | 2.0-3.0 |
| Chromium chemistry | Trivalent, no hexavalent chromium |
| Line types | Rack, barrel, manual and automatic lines |
Set the bath at 40 ml/L and check it against the 30-60 ml/L range rather than against the set point alone. The two variables move together: toward the top of the range, keep the immersion at the short end of 25-45 s, because a stronger bath builds the film faster; toward 30 ml/L, the longer end of the time range is usable without over-colouring. The 35 s figure is the starting point most lines settle on.
pH is the variable that drifts first. Hold it at 2.5 inside 2.0-3.0 and check it before a shift rather than after a problem appears: nitric acid carried over from the bright dip pushes the bath one way, and drag-out on the work pushes it the other. Temperature is simply room temperature, around 25 °C. There is no heater to fail and nothing to chill unless the workshop itself runs very warm.
Treat this like any of your other plating solutions: keep a log of make-up, pH and immersion time, and top up on analysis rather than on colour. If the film starts looking weak at a concentration that used to work, the cause is usually upstream — a spent bright dip, a cold rinse, or a zinc deposit that has changed — before it is the passivator. If this is your first trivalent bath, ask your sales contact for a starting maintenance schedule.
The passivation film's first job is anti-white-rust. It holds back the white corrosion product that forms on zinc in damp air, and it does that without a topcoat. Where a drawing asks for longer salt spray than the film alone reaches, the same bath pairs with our chrome-free sealers, applied after the final rinse and before drying.
Before comparing salt-spray hours with another shop, fix the test conditions. The result depends on the zinc thickness under the film, the film itself, whether a sealer was used, and the method used to test it — a figure quoted for one line rarely transfers to another unchanged. Film build is something you control: concentration and immersion at the top of the window lay down more film than a short dip at the bottom, and that difference shows up in corrosion results long before it shows up in colour. Transfer time matters too; a part that dries between the passivator and the rinse does not give the same result as one that goes straight through.
Many metal plating services quote salt spray on the finished component rather than on the coating step. Send us the deposit thickness, the sealer you intend to use and the test method you work to, and we will tell you which combination to trial first.
Aerospace work is rarely a single process. A shop may run zinc on fasteners and ground-support hardware, cadmium on high-strength steel, and zinc-nickel on parts that see heat. This passivator has a clear place in that mix, and a clear boundary.
On zinc-plated fasteners, jigs, tooling and ground-support equipment, the blue film gives a uniform finish and a predictable corrosion result, and the colour makes it easy to separate passivated from unpassivated stock on the shelf. Where the drawing calls for cadmium or a zinc-nickel alloy, this is not the substitute — those systems need their own passivation chemistry, and we supply those separately.
The practical value on an aerospace line is control: a room-temperature bath, a pH that is checked rather than assumed, and a bath life long enough that a small batch can be run without mixing fresh plating solutions every time. If your specification names a salt-spray figure or a particular test method, send it with the enquiry so the recommendation is made against it rather than against a general claim.
Construction hardware lives outdoors, and zinc plating with a blue passivation is one of the most common ways to protect the steel in it. Hinges, brackets, anchors, bracing and fixing plates all go through the same sequence: plate, passivate, dry, pack.
The requirement is usually straightforward. The part has to look acceptable on site, and it has to survive the first winters without white rust appearing on the shelf or in the wall. A blue-white film does both, and because it does not hide the deposit, an inspector can see the coating quality instead of a heavy colour sitting on top of it.
Operationally, what matters is throughput. Architectural hardware is produced in long runs, and the metal plating process has to deliver the same result at the start of a shift and at the end. A bath with a wide working window and a long service life removes most of the fiddling; the rest is rinse discipline and prompt drying, which is where most finish complaints on this kind of work actually start.
If the hardware will be painted or powder coated after plating, say so at the enquiry. The passivation step and the coating step need to be planned together, because the surface the coater receives is the surface the passivator leaves.
Zinc passivation and aluminium anodizing are different chemistries, and we supply both. Where this passivator builds a thin conversion film on zinc, anodizing grows an oxide layer into the aluminium surface itself — a harder, thicker film that carries colour and can be sealed afterwards.
Our aluminium range covers the anodizing line rather than a single step in it: the process chemicals for the anodic film, electrolytic colouring additives such as the Phoenix EB 204A-204B divalent tin salt process, and the sealing agents that close the film. A shop that buys acid zinc plating chemicals and anodizing chemicals from us gets both chains from one contact instead of two supply relationships.
The two processes are often confused because both are finishing steps that protect a metal surface. In practice they solve different problems: anodizing is chosen where the aluminium itself has to carry the wear and the colour, while passivation is chosen where a zinc deposit has to keep its appearance and hold back white rust. If you are specifying one and your customer is describing the other, tell us what the part has to do and we will say which route fits.
Not every problem in a finishing plant is a plating problem. Wetting, levelling and substrate preparation decide how a coating sits on a part long before the plating line is involved, and we supply the surfactants and coating chemicals that sit on that side of the process.
Surfactants do the unglamorous work: they lower surface tension so a cleaner reaches the metal under a film of oil, and they help a coating spread evenly instead of crawling or cratering. On a coating line that shows up as a smoother film with fewer defects to rework. On a plating line the same chemistry sits in the degreasing stage, where a cleaner that wets badly leaves the kind of residue that later appears as an adhesion failure.
Many of the metal plating services we supply also run a paint or powder line, and the defects that reach us for diagnosis sit somewhere between the two. We hold coating additives alongside the plating range so a shop that does both can source them from one supplier, and so a defect can be looked at as one problem rather than two suppliers pointing at each other.
Alodine-type conversion coating is the third member of the family, and the one most often confused with both anodizing and passivation. It is a chemical conversion layer on aluminium, applied by immersion or spray, that prepares the surface for paint or adhesive and adds a degree of corrosion protection of its own.
The difference from anodizing is thickness and mechanism: anodizing grows an oxide into the metal, while a conversion coating reacts with the surface and leaves a thin film on it. The difference from zinc passivation is the substrate — this passivator is for zinc, and conversion coatings are for aluminium and its alloys. Where the part is aluminium and will be painted, a conversion coating is usually the preparation step; where it is aluminium and will be left bare, anodizing usually is.
We supply the chemicals for both routes, and they sit alongside the metal electroplating range rather than replacing it. If you are setting up a line that handles both steel and aluminium parts, tell us the sequence you plan and we will confirm which chemicals belong at each step.
Anodizing aluminum is a crucial process for industries that demand high-performance materials. Our aluminum anodizing service offers a robust solution for enhancing the durability and corrosion resistance of aluminum components, and by using advanced techniques we turn anodised aluminium into a material that is not only resilient but also visually striking. The aluminium anodizing process is meticulously controlled for uniformity and quality, which makes it suitable for applications ranging from aerospace to consumer electronics. Alongside alodine coating, our services include the passivation of stainless steel, a critical process for preventing corrosion and maintaining the integrity of stainless steel surfaces, so your components stay in optimal condition even in the most demanding environments. Share your part requirements and our team will confirm the process route and finish that suit your application.
In the automotive industry, the longevity and durability of metal components are crucial. Metal plating services play a vital role in ensuring that parts such as brake calipers and engine components resist corrosion and wear, and with electroless nickel plating services manufacturers can achieve uniform coatings that extend the lifespan of these components. Passivation of stainless steel is likewise essential for preventing rust in exhaust systems. The TR-290LC Trivalent Chromium Passivator from Fengfan Trade offers a reliable solution for achieving a blue finish that not only improves aesthetics but also provides superior corrosion resistance. Tell us which components you are treating and we will confirm the most suitable process for your production.
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.
Both acid zinc and alkaline zinc. The bath is made up the same way for either, so a shop running an industrial metal plating line for mixed hardware can keep one passivation tank instead of two. The film is blue-white on both, and the working parameters do not change between them.
The passivator is only one input. Colour is decided first by the zinc deposit itself, and the acid zinc plating chemicals and the bright dip underneath it matter as much as the passivation bath. Beyond that, concentration and immersion time at the top of the window build a stronger colour than a short dip at the bottom, and a part that dries between the passivator and the rinse will look different from one that goes straight through. Fix the deposit, the bright dip and the transfer time, and the colour settles.
Yes to both. The working window is wide enough for a programmed hoist and for hand dipping, and the same bath passivates barrel loads. Most metal plating services that run both rack and barrel work use one passivation tank for the two, with the barrel loads taking the longer end of the 25-45 s immersion range and a quicker transfer to the rinse.
Some solution comes out of the bath on the parts and ends up in the rinse water, which is normal. That dilute rinse can be returned to the passivation tank as make-up instead of being sent to waste treatment, which is one of the reasons the bath has a long service life. Keep the rinse volume under control so the return does not dilute the bath faster than you can correct it.
It is a conversion film, not a plated layer, so it does not build the kind of thickness a zinc or nickel deposit adds. On ordinary hardware this is not something you need to allow for. On a thread or a press fit with a very tight tolerance, run a sample through the full sequence, including the sealer if you use one, and check the fit before you commit the batch.
The make-up contains no hexavalent chromium, and the process has been tested by SGS. Ask your sales contact for the current certificate and confirm its exact scope covers the product and the market you are supplying into. The SGS report and the batch paperwork are separate documents, and buyers often need both on file.
Four things: the zinc deposit thickness you are passivating, the rinse stages your metal plating process already has, the salt-spray or appearance target the part has to meet, and whether a sealer will be part of the sequence. With those, we can confirm the starting concentration, the immersion time and whether the passivator alone is enough for your requirement.
