Fengfan Cyanide Free Alkaline Zinc Plating Chemicals Brightener High Throwing Power ZN-265

Product Overview

ZN-265 is a concentrated brightener for cyanide-free alkaline zinc plating, built from a blend of polyamine compounds rather than a single salt. Dosed into a zincate bath, it produces a smooth, bright, fine-grained zinc layer on steel parts, and it is designed to take the place of a conventional cyanide zinc system outright rather than to top one up.

The concentrate carries no free cyanide. That changes what the line has to manage day to day: the bath stays alkaline throughout, waste treatment is no longer built around cyanide destruction, and the chemistry behaves predictably across a broad zinc metal span — an important quality when the same tank plates a different workload every week.

We supply it as three liquids: a brightener, an additive and a purifier. Splitting the system that way lets a bath be corrected one variable at a time instead of through a single blended product. It sits in our range of electroplating chemicals for lines that zinc plate steel parts in alkaline media, and it is worked on both rack and barrel equipment.

The sections below set out the working ranges, how a bath is charged and kept in condition, where the product earns its place on a line, and how it behaves when a tank is dirty or when parts go on to passivation and sealing.

Specifications

Product Advantages

• Throwing power that reaches inside the work. Brightness and coverage hold in recesses, tube bores and other low-current areas, which is the difference between a rack of pipe fittings that plates evenly and one that comes out bright at the edges and dull inside — the classic complaint in industrial metal plating.
• One brightener for both line types. The same bath covers a barrel load of small parts and a wide rack job, so there is no second product to stock and no second set of dosing rules to learn.
• Brightness that survives a warm bath. The deposit still reads bright and decorative at bath temperatures up to 48 °C, so a line without heavy cooling keeps its gloss through a long shift instead of fading as the tank warms.
• A wide zinc metal span keeps the bath forgiving. Metal content can drift between analyses without the deposit falling away, which buys time on a busy shift and takes pressure off the titration schedule.
• Nothing to add and nothing to destroy. There is no free cyanide in the concentrate, so the bath is alkaline from start to finish and the waste stream is simpler to handle.
• Correct one thing at a time. Brightener, additive and purifier are separate liquids, so when brightness drops you top up the brightener without dragging the rest of the bath with it — worth a great deal in an electroplating line where a single blended additive forces you to over-dose everything to fix one variable.
• Fewer full-bath corrections. Because the purifier is held back until it is actually needed and the other two are dosed against ampere-hours, the bath spends more of its life inside its working ranges.

Rack and Barrel Line Notes

The bath chemistry does not change between a rack line and a barrel line; what changes is the way the parts meet the solution.

On a rack, cathode movement of 8 to 12 cycles per minute keeps fresh solution at the part face and evens out the boundary layer. Without that movement the low-current side of a complex part can lose brightness even when the analysis is perfect. Jig contact deserves as much attention as the chemistry: one weak contact point will show as a dull patch that no brightener addition will fix, so check the rack before touching the bath.

In a barrel, rotation of 6 to 8 revolutions per minute is the working range. Overfilled barrels plate slowly and unevenly, because parts shield one another and the solution cannot exchange inside the mass. Load within the barrel's normal working volume and leave small parts enough room to tumble past the contacts.

The current density window runs from 0.5 to 8 A/dm², which covers light decorative work and heavier functional deposits on the same bath. If you are working towards the top of that window for thickness, confirm the dwell with us first — long holds at high current build a coarser layer that brightener cannot smooth afterwards.

Keep the bath filtered and the anode bags clean. Sludge on the anode alters current distribution long before it shows up in the analysis, and it is one of the commonest reasons an electroplating line blames the brightener for a problem that sits in the tank. Because the chemistry is unchanged between the two setups, a job can move from rack to barrel without rebuilding the plating process around it.

Use Scenarios

• Automotive brackets, fasteners and pipe fittings. Racked parts with bends and recesses come out with even thickness and brightness — the barrier these coatings exist to provide on parts that see road salt and weather.
• Electronics housings and enclosures. Barrel-plated shells and small pressed parts need brightness on visible faces and coverage in folded edges; the low-current behaviour of this brightener delivers both in one load.
• Tube, pipe and deep-drawn parts. Interiors are the hardest place to plate, and throwing power is what puts a sound layer inside a bore instead of stopping at the mouth — the detail that decides whether a metal plating process passes inspection on tubular work.
• Job shops running mixed geometry. A line that plates a different part every few days cannot rebuild the bath for each job; a brightener that works across a wide current density window and a broad zinc metal span keeps industrial metal plating schedules on track from one job to the next.
• Conversion away from cyanide. An existing alkaline zinc line can move onto this chemistry and keep its passivation and sealing steps, so the change stays in the plating tank rather than spreading through the whole shop.
• Hardware, builders' fittings and general barrel work. High-volume parts that must be bright enough to take a decorative passivation and sound enough to face a salt-spray requirement.

Impurity Behaviour and Passivation

Alkaline zinc baths accumulate contaminants: calcium and magnesium carried in with the work and the water, iron from parts that were not fully pickled, lead, cadmium and chromium from scrap or from upstream operations. In industrial electroplating that build-up is normal; what matters is how the brightener behaves once it happens. This one keeps producing a bright, coherent layer past the point where a less tolerant product starts to grey out, and the deposit still takes a passivation film.

Watch for the usual signals: a bath that turns hazy, brightness that drops first in the low-current areas, a passivation film that comes out dark or patchy, or fine spots on barrel work. Those are impurity symptoms rather than brightener symptoms, and adding more brightener makes them worse and costs more.

The purifier is the answer to that, and it is deliberately the component you reach for least. It is normally left out of a new bath; dose it when incoming work is known to be dirty or after a sodium hydroxide addition, which is when contaminant levels tend to step up. Because it is a separate liquid, the bath can be treated without touching the brightener or additive levels.

Passivation is where a good zinc layer proves itself. The deposit accepts the common post-treatments — blue-white, colour and the rest — and holds an even appearance through them, so a line does not have to choose between a bright as-plated finish and a passivation that actually performs. Where parts are sealed after passivation, the film sits on a coherent zinc layer rather than a patchy one, and that is where corrosion performance is won or lost.

Charging and Running the Bath

1. Confirm the working volume and the zinc metal target with our technical team before the first charge of plating chemicals; a bath built to the wrong volume is the hardest kind to correct later.
2. Dissolve the zinc oxide into the sodium hydroxide solution rather than the other way round. Add the oxide steadily, because the reaction runs warm, and keep the tank stirred.
3. Bring the tank up to volume with water, mix thoroughly, and check ZnO and NaOH against the specification table before any additive goes in.
4. Charge the brightener and then the additive at the concentrations listed in the table, stirring each one in fully before the next. Add them one at a time; a single combined addition makes it impossible to tell which component a later change came from.
5. Leave the purifier out unless the work is known to be dirty or sodium hydroxide has just been added. It is a corrective, not a routine charge.
6. Filter the bath and electrolyse it at low current density on a dummy load before production parts go in. This pulls metallic impurities out of a new bath and settles the chemistry.
7. Plate a test panel that spans the current density window, including a low-current area, and inspect brightness and coverage before releasing the line.
8. Log the analysis, the temperature and the ampere-hours after each shift. The consumption figures in the specification table are the reference for top-up calculations; the log is what turns them into a working dosing plan.
9. When a correction is needed, change one component at a time and plate a panel before the next change. That habit keeps a plating process stable and makes a fault easy to trace.

Packing and Ordering

Related Products

• Fengfan Brightener for SZ-30B Sulfate Zinc Plating — for sulfate acid zinc lines, where the bath chemistry and brightness behaviour differ from an alkaline tank.
• Fengfan Bright Zinc Alkaline for Rack and Barrel Plating ZN 50 — a second alkaline zinc brightener in the range, useful when you want to compare two systems on the same work.
• Fengfan Brightener for Cyanide Free Alkaline Zinc Plating ZN-500 — another cyanide-free alkaline option, so a shop running several lines can hold both a main and a backup chemistry.
• Fengfan Phoenix EB 204A-204B Divalent Tin Salt Electrolytic Coloring Additive — for colouring anodised aluminium before sealing.
• Fengfan Phoenix Seal 149-L Middle Temperature Sealing Agent for Aluminum Anodizing — seals the anodic film after colouring.
• Fengfan Phoenix Seal 149-T Medium Temperature Sealing Agent — the companion seal for medium-temperature anodising lines.
• Fengfan High Deposit Brightness Copper Plating FI-970 Bright Acid Copper Plating Process — where a bright copper layer sits under nickel or under a decorative stack.
• Fengfan Wood Stone Concrete Nano-Protective FF-4219 — surface protection for mineral and concrete substrates rather than for plated steel.
• Fengfan Nickel Purify P3 — a purification treatment for nickel baths that have picked up contamination.
• Fengfan Environmentally Friendly Chrome Mist Inhibitor FF-116 — mist control for chrome plating tanks.
• Bought together with a trivalent passivation and a sealant from the same range, the zinc layer and its post-treatment arrive as one set of plating chemicals on one order instead of being assembled from three suppliers — a practical advantage for industrial electroplating lines running continuous schedules.

Coating Ductility for Forming

Ductility is decided at the bend, not in the tank. A bracket bent to fit after plating, a terminal crimped onto a cable, a fastener staked into a housing, a tube end flared — each of those pulls the zinc layer across a fold, and a stressed deposit opens up there as fine crazing or flakes away along the line of the bend. Nothing shows in the plating record; the reject surfaces at assembly.

What the chemistry contributes

ZN-265 is built on polyamine compounds and lays down a smooth, bright, fine-grained and flexible zinc layer in the alkaline bath. That ductility belongs to the deposit itself rather than to a film applied over it, so it carries through the forming step as long as the layer has been run inside its working window. It is one reason this brightener suits industrial electroplating work on parts that are still going to be shaped after they leave the line.

Keeping the deposit ductile

- Do not chase gloss by over-dosing. Brightness comes from holding ZN-265A within its 10–14 mL/L charge and topping up against the 80~180 mL/KAH consumption figure. Extra brightener pushed in to lift a dull bath builds internal stress into the deposit, and a stressed layer is exactly what cracks at a fold. - Watch thickness and current density together. The 0.5–8 A/dm² window covers decorative and functional work, but long dwells near the top of it build a coarser, harder layer. Where a part needs a heavy deposit and is formed afterwards, confirm the dwell with us before the run. - Hold the bath inside its temperature range. Brightness is retained up to 48 °C and the bath runs to 52 °C, but a tank that drifts warm while the brightener is also being pushed is where ductility is most often lost. - Treat contamination early. Iron, lead and calcium raise deposit stress and dull the finish at the same time. The purifier is the corrective, dosed when the analysis or a run of dirty work calls for it, and correcting early costs far less than correcting after a batch of bent parts has failed.

Telling a ductility problem from an adhesion problem

Both look like flaking and they are fixed in different places. If the layer peels back cleanly to bare steel in sheets, the fault is usually pretreatment — oil, scale or a smut film left on the part — and no change in the brightener will help. If the coating crazes into a network of fine cracks across the bend while staying bonded, the deposit itself is too stressed, and the bath rather than the cleaning line is where to look. Plate a coupon, bend it and inspect the fold before committing a production load.

Forming before or after passivation

Where the sequence allows it, form the part before passivation. A trivalent passivation film is thin and does not stretch with the zinc beneath it, so bending a passivated part cracks the film on the outside of the bend and leaves that strip unprotected in salt spray even though the zinc itself is sound. If the order cannot be changed, keep the bend radius generous and consider a sealant from the same plating chemicals range to close the film again.

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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