Fengfan High Corrosion Resistance Water Soluble Sealant Chrome Free Sealant PN-6

Product Overview

PN-6 is the sealing stage of a zinc plating line, not another passivation. Plating services add it after the passivation and before the drying oven, and it exists to keep the protection the passivation film already gives through packing, stacking, transport and the salt-spray cabinet.

The concentrate is water-soluble and chrome-free. There is no hexavalent chromium in the product or in the working bath, so the drag-out and rinse water from this tank carry none of the hexavalent chromium load that conventional chrome-based post-treatments bring into a plant. In industrial metal plating, that single change often decides whether a post-treatment step can be run at all under a site's wastewater limits.

Mixed with water the sealant forms a thin, clear film over the passivated surface. The bath sits at room temperature and parts dry in the same oven the line already uses: one tank is added between the final rinse and the dryer, and the work either passes through it on the rack or is sprayed on the way past. Nothing about the plant layout has to change.

It is not a paint, a lacquer or a conversion coating. The passivation still decides the colour and the base corrosion figure; the sealant decides how much of that figure survives real handling. That distinction matters when a part fails salt spray, because the answer is often here rather than in the plating tank.

Typical users are job shops and captive lines running rack work, baskets of small parts, or mixed batches of stampings, fasteners and pressed components. Lines running zinc nickel plating over steel use the same step after their own passivation, once the passivation type has been checked.

Performance Advantages

• Superior corrosion resistance. Sealing typically improves the protective effect of the passivation film in neutral salt spray testing by 0.2 to 0.5 times. The figure to judge it by is your own part, plated and passivated as usual, then tested with and without the seal — the comparison a plating services customer will ask to see.
• Eco-friendly, chrome-free chemistry. With no hexavalent chromium in the product, the working bath, its drag-out and its rinse water stay outside the Cr(VI) waste stream, which simplifies rinsing, spill control and operator protection compared with a chrome-based post-dip.
• Enhanced surface protection. The dried film sits on top of the passivation and takes the abrasion of racking, packing and transit, so the surface underneath arrives at the customer the way it left the metal plating line.
• Cost-effective operation. The product is diluted with water, runs at ambient temperature and needs no equipment beyond one tank, while the parts it saves are the ones that would otherwise fail salt spray, the kind of rework every metal plating services operation counts in its scrap figure.
• Versatile application. The sealant sits comfortably after the passivation types a line already runs, blue, white, colour and black films included, and it handles mixed part sizes as long as the work drains properly on the way to the oven.

Operating Parameters

Process Flow

1. Zinc plating. This is the step that sets the ceiling for everything after it in the metal plating process, so plate to the thickness the drawing or specification calls for; the sealant protects the zinc that is there and adds nothing to it.
2. Drag-out and recycle. Let the work drain over the plating tank before the first rinse, so carried-over zinc returns to the metal plating bath instead of the drain.
3. Rinse. Clean water, and enough of it that no plating salts are left to dry on the surface.
4. Neutralize. A short dip in 2–3% nitric acid removes the film left by the plating bath and gives the passivation a clean surface to work on.
5. Passivate. Run your existing passivation to its own parameters; the sealant does not replace it and cannot rescue a weak passivation.
6. Rinse. Rinse thoroughly again, because passivation drag-out carried into the seal tank is one of the commonest reasons a seal underperforms.
7. Seal. Immerse the work and withdraw it straight away, or spray the bath solution onto the part; in immersion there is no dwell time to manage.
8. Dry. Parts go through the normal oven, the film sets as the water leaves, and the work is ready for inspection.

Usage Scenarios

Enhancing Automotive Component Durability

Fasteners, brackets, stamped housings and under-hood hardware are routinely zinc plated or zinc nickel plated, then passivated, before they go into a vehicle, and the sealing step is what carries that finish through assembly, storage and years of road salt. A sealed part keeps its passivation film intact where an unsealed one shows white corrosion first. On threaded parts, confirm that the film you build at your chosen concentration still leaves the thread inside tolerance, and agree the salt-spray acceptance figure with the customer rather than assuming the multiplier applies unchanged.

Optimizing Electronics Manufacturing

Chassis parts, shielding cans, connector shells, screws and mounting brackets leave a metal plating services line with the same expectation: they have to look uniform by the time they reach the assembly line. A sealed rack of small zinc-plated parts comes off with a consistent tone instead of patchy passivation, and spraying covers large flat panels and housings that will not fit in a tank. Where a customer inspects cosmetic surfaces, check the first parts off the rack before the batch runs.

Improving Aerospace Component Performance

Zinc-plated hardware on an aerospace programme is bought to a drawing, and the drawing normally names the passivation system and the test it has to survive. What the sealant can do is lift the protection the approved passivation already delivers; what it cannot do is stand in for the qualification your customer requires. Agree the test method and the acceptance figure before a batch is sealed.

Streamlining Industrial Equipment Maintenance

Gears, guards, frames, hydraulic fittings, bolts and barrel-plated small parts are everyday work for industrial metal plating, and sealing them cuts the callbacks that come from parts corroding in storage or in a wash-down environment. Spraying reaches fabrications that will not fit a tank, and a single seal tank can serve very different part families as long as they drain properly before the oven.

Enhancing Architectural Metalwork

Window and door hardware, balustrade fittings, exposed fixings and brackets face weather, cleaning chemicals and handling on site. Sealing after passivation holds the colour the architect approved and slows the drift to white corrosion on edges and threads. Where a strong colour is specified, settle the passivation-and-seal combination on a sample panel first, which is the normal route for plating services on a project of this kind.

Bath Make-Up and Handling

• Start from water above pH 7. The sealant flocculates under acidic conditions, so the water going into a new bath has to be neutral or slightly alkaline; check the supply before the tank is filled, not after a batch has been sealed.
• Remove flocculation properly. Insoluble floc is taken out of the bath and sent to wastewater treatment; left to settle, it lands on the work and dries into a rough, uneven film.
• Plan around barrel lines. The sealant is not suitable for direct use on an automatic barrel production line because it closes the perforations in the drum, so a metal plating services operation running barrels transfers the work to a basket or rack for the sealing step.
• Tune the film with concentration, not with dwell time. Concentration is the lever for how thick the film sits, so move it in small steps and check appearance and salt spray at each step instead of jumping to the top of the range.
• Watch the two everyday drifts. pH creep and dilution from wet work are what usually turn a working bath into a thin one on an industrial metal plating line; a daily pH check and a look at the tank surface catch both early.

Related Process Chemicals

• The wider range. Fengfan International Trade supplies plating additives, intermediates and metal finishing chemicals, backed by a Wuhan chemistry group that has worked in surface treatment since 1984; the lines below are the ones most often bought alongside a post-treatment seal on a metal plating line.
• Fengfan Brightener for SZ-30B sulfate zinc plating. The brightener side of a sulfate zinc bath, for lines that plate continuously or run single workpieces.
• Fengfan Bright Zinc Alkaline ZN 50. An alkaline bright zinc system for rack and barrel work.
• Fengfan Brightener for Cyanide Free Alkaline Zinc Plating ZN-500. For shops moving an alkaline line away from cyanide.
• Fengfan Phoenix EB 204A-204B divalent tin salt electrolytic coloring additive. For colouring anodised aluminium before its own sealing step.
• Fengfan Phoenix Seal 149-L. A middle-temperature sealing agent for aluminium anodising.
• Fengfan Phoenix Seal 149-T. The medium-temperature sealing agent in the same Phoenix Seal family.
• Fengfan FI-970 bright acid copper plating process. A high-deposit-brightness acid copper process for decorative and technical work.
• Fengfan Nickel Purify P3. A purifier for nickel baths that have picked up contamination.
• Fengfan FF-116 chrome mist inhibitor. An environmentally friendly mist suppressant for chrome plating baths.
• Fengfan FF-4219 wood, stone and concrete nano-protective. A protective treatment for mineral surfaces, outside the plating line but supplied from the same range.

Ordering and Delivery

Part Validation Checks

• Run the trial through the whole line. A coupon dipped in the seal tank on its own proves very little, because the passivation drag-out, rinse quality and oven dwell of your own metal plating process all change the result. Plate, passivate, seal and dry the parts exactly as production will, then judge them.
• Test the geometry that is hardest to drain. Blind holes, recesses, folded edges and stamped burrs hold more solution than a flat face and dry to a heavier film, so put those features on the trial parts rather than sending polished flat coupons through.
• Compare sealed and unsealed parts under the same salt spray conditions. Use the same substrate, plating thickness, passivation and test method for both sets; the acceptance figure a customer signs off applies to the finished part, not to a general multiplier taken from a data sheet.
• Gauge threads at the concentration you intend to run. Film thickness follows concentration, so a thread that passes its go/no-go gauge on a lean bath can tighten near the top of the working range. Seal a sample, check the gauge or run the mating nut on, and settle the working concentration from that result.
• Measure electrical contact as an assembly. On grounding screws, connector shells, chassis studs and similar parts, assemble the joint and measure resistance rather than assuming the film is thin enough to ignore. Where contact resistance is critical, mask the contact area or seal only the corrosion-exposed surfaces, and agree that approach against the drawing before the batch runs.
• Handle and pack the part before you sign it off. The film earns its place by surviving racking, stacking, wrapping and transport — the handling steps any metal finishing job goes through — so wipe, stack and unpack the trial parts the way the real order will travel.
• Write the bath down beside every result. Concentration, pH, bath temperature, drying temperature and dwell all belong next to the salt spray and appearance notes, so a good result can be repeated and a poor one points at the variable that moved.
• Scale up one part family at a time. Fasteners, flat panels and barrel work transferred to a basket each need their own confirmation, because a concentration that suits one family may be too heavy or too lean for the next.

Eco-Friendly Innovation

Choose a chrome-free sealant for anodized aluminum that meets the growing demand for environmentally responsible finishing without sacrificing performance. It is formulated to support eco-conscious programs in aluminum anodizing and electroless nickel plating, and it fits naturally into the sustainability goals of paint chemical suppliers and surfactant manufacturers. The result is a greener finishing option that still delivers the protection and appearance your customers expect, so you can reduce environmental impact while holding to the same quality standards. Contact us to confirm the grade and suitability for your specific line.

Technical Support & Model Matching

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.

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