AL-200 is a chromium-free passivator for aluminum and aluminum alloys. In the working bath it reacts with the metal and builds a titanium-zirconium composite conversion film — a thin, colorless layer that protects the surface and gives the next coating or adhesive something reliable to grip.
It sits near the end of the cleaning sequence and before the coating step. Typical work includes architectural extrusions heading for powder coating, castings and machined components going into assembly, and enclosures, fixtures and signage that will spend their life outdoors. Shops that also run aluminum anodizing use the same bath as a passivation stage on parts that need a clean, protected surface before the next operation.
There is no hexavalent chromium in the formulation and no nickel in the film. For a plant phasing out chromate conversion coatings that is the practical route: it replaces trivalent and hexavalent chromium pretreatments, runs in the tank and racking you already have, and leaves a film that is invisible on the finished part.
Dosing, temperature, immersion time, water quality and agitation are set out in the table below. The bath works at normal plant temperature, relies on filtration rather than air agitation, and fits into an existing line without new equipment, whether that setup is a coating plant or a small aluminum anodizing kit.
| Item | Standard | Optimal |
|---|---|---|
| AL-200 | 10~25 g/L | 15 g/L |
| Temperature | 20~35 °C | 25~30 °C |
| Pure water conductance | ≤30 µs/cm | ≤15 µs/cm |
| Processing time | 1~5 min | 3 min |
| pH | 4.0 ~ 5.0 | 4.0 ~ 5.0 |
| Air stirring | Not recommended | Not recommended |
| Circulating filtration | Recommended use | Recommended use |
The film is a composite conversion layer rather than a plated deposit. The bath reacts with the aluminum itself and builds a mixed titanium-zirconium oxide layer that is chemically bonded to the substrate. That is why a passivated part can go straight from the final rinse to a drying oven, a paint line, an assembly bench or an aluminum anodizing service without an extra handling step in between.
Because the layer grows out of the surface instead of sitting on top of it, it copes with the differences between alloys far better than a coating that simply dries in place. Sheet, extrusions, castings and die-cast parts all form their film in the same bath, at the same dose and the same immersion time — a real advantage in a shop running three or four aluminum grades through one line without wanting three or four passivators on the shelf.
The chemistry is also designed to stay out of the way of whatever comes next. It does not interfere with liquid paints, powder coatings, printing inks or structural adhesives, and it does not have to be stripped before a later finishing step. Parts that are passivated and packed for a customer arrive with a protected surface that still reads as aluminum.
Broad compatibility is the point of the design: the same bath serves a mixed-alloy job shop, a coating line and a shop running an aluminum anodizing kit in small batches, so a plant can standardize on one product and one set of parameters instead of matching a different passivator to every substrate.
Passivation is judged by how long a part survives before corrosion shows. On aluminum, the conversion film slows the ingress of moisture and contaminants into the surface and reduces the under-film corrosion that starts at edges, drilled holes and cut faces — the places where a coating is thinnest and bare alloy is most exposed.
In neutral salt spray testing, passivated aluminum holds out considerably longer than untreated aluminum, and parts that are passivated before painting keep their appearance longer in service, because corrosion has to break through the film before it can lift the coating.
We deliberately do not publish a single salt spray hour figure. The result depends on the alloy, the preparation before passivation, the film formed in your bath and the test conditions, and a number copied from someone else's panel tells you very little about your own part. If a customer or a specification asks for a figure, send us the alloy and the test method and we will confirm what applies to your case.
Corrosion protection is also cumulative rather than absolute. Passivation works alongside the alloy you chose, the coating thickness you apply and the aluminum anodizing process — it does not replace any of them. Used at the right point in the chain, it buys time at the weakest points of the part.
Compliance without a rebuild. Moving off a chromate process is usually a paperwork project, not an engineering one. This passivator goes into the tank that held the old conversion coating, at the same point in the sequence, so the change is a new bath make-up and a new set of documents rather than a new line.
Cosmetic parts stay saleable. The film is colorless, so there is no polishing step after passivation and no patchy discoloration on bright or dyed surfaces. The rework that chromate lines fight with simply does not arise.
One product for a mixed-alloy plant. A shop that runs sheet, extrusions and die castings keeps one passivator on the shelf instead of matching a product to every grade, which simplifies dosing, purchasing and operator training at the same time.
Stronger paint and adhesive performance. Failures in coated aluminum usually start at the interface. A conversion film turns that interface into a bonded oxide layer, so the coating has something to hold on to and under-film corrosion has further to travel before it becomes visible.
A simple tank to own. There is no heater to run and no blower to feed, so the bath is one of the quieter pieces of equipment on a metal finishing floor: it is dosed, filtered and checked, and nothing else in the building has to change to accommodate it.
Powder coating and liquid paint pretreatment. Extruded facade sections, panels, enclosures and fabricated frames are passivated after cleaning and deoxidizing, then coated. The conversion film gives the powder or paint a bonded oxide to adhere to and reduces the under-film corrosion that appears first at cut edges and drilled holes.
Adhesive bonding and assembly. Where aluminum is bonded rather than painted — panels, brackets, structural joints — the passivated surface gives the adhesive a consistent, contamination-free interface, which matters more in production than any single bond strength figure quoted on a datasheet.
Outdoor, coastal and marine service. Signage, lighting enclosures, architectural fixtures and infrastructure hardware that face humidity, salt air and rain benefit most, because the film slows the first stages of corrosion on parts that cannot easily be maintained once installed.
Die casting and mixed-alloy production. Castings with porosity and varied alloying elements, run alongside extrusions and sheet, all passivate in the same bath, so the mixed shop does not have to split the work or keep separate chemistry.
Anodizing lines. Shops that offer an aluminum anodizing service use the bath as a passivation stage for parts that will be anodized or that simply need protection before they reach the anodizing tank.
Corrosion protection is the core of the value here: the passivation treatment is designed to raise neutral salt spray endurance, the measurement buyers watch most closely in harsh service environments. The film deposits clear and colorless, so anodized aluminum surfaces keep the appearance the specification calls for. In use, the process is deliberately simple, running on standard dosing and standard temperature conditions with no specialist equipment changes required. That simplicity carries through to the people running the line, since fewer adjustments mean a more consistent workflow and less training overhead on finishing lines that already run an aluminum anodizing process.
It is also applied as a surface pretreatment on aluminum parts that will subsequently be coated or painted, preparing the surface ahead of the next finishing step. Buyers should confirm with our team that the treatment matches their specific downstream coating or paint system before committing a full production run.
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 means there is no hexavalent chromium anywhere in the process. The protection does not come from a chromate film but from a titanium-zirconium conversion layer formed out of the aluminum surface, so there is no Cr(VI) to handle, declare or rinse away, and no chromate conversion coating step to monitor.
Yes. Passivated aluminum holds out noticeably longer in neutral salt spray than untreated aluminum, and coatings applied over the film resist under-film corrosion for longer. How many hours you will see depends on the alloy, the film formed in your bath and the test conditions, so ask your sales contact for data matched to your alloy and test method rather than relying on a single headline figure.
Yes. It works as a pretreatment ahead of anodizing: parts are cleaned, passivated, rinsed, then taken through the aluminum anodizing process as normal. The passivation stage leaves the surface clean and protected and does not interfere with the anodic layer. If your line runs an unusual sequence, send us the steps and we will confirm where the bath fits.
Aluminum alloys and die-cast aluminum are both in scope, including sheet, extruded profile, castings and machined or fabricated parts, and mixed-alloy shops run them all through one bath. Tell us the alloy series and the surface condition before passivation and we will confirm the cleaning and deoxidizing steps ahead of the bath.
No. The film is colorless and transparent, so bare, bright, dyed and anodized aluminum keep the look they had before passivation. There is no discoloration and no residue to polish off, which is why cosmetic parts can go through the bath without an extra finishing step.
