Fengfan Wire type Galvanized Brightener Sulfate Zinc Plating SZ-75

Product Overview

A liquid brightener for sulfate zinc plating of steel wire, dosed into a zinc sulfate bath together with a separate make-up agent. It is built around continuous wire lines, where the strand runs through the cell at speed and the deposit has to build evenly, stay bright, and remain ductile enough for the coil to be drawn or formed after plating.

Wire galvanizing is one of the longest-standing uses of acid zinc plating chemicals, and the reason is practical. A sulfate bath plates quickly at the current a wire line runs at, and the zinc bonds tightly to steel. The risk is brittleness: a hard, stressed layer cracks the moment the wire passes through a die. This brightener is balanced for that — a fine-grained deposit with good adhesion that keeps its ductility after plating.

Wire that is drawn or deep-processed after plating is the case this brightener was really designed around, and the high-carbon end of the range is where that matters most, because those wires work hardest in the die. General steel wire runs on the same bath without a change to the routine, which is why a single line can carry several products at once.

The additive works as part of a two-part system — the brightener itself and a make-up agent that is replenished to cover drag-out — so the bath stays inside its working range through a long run instead of drifting between shifts. For an electro plating shop already running a sulfate line, that makes the change a dosing routine rather than a new process.

Performance on the Wire Line

• Adhesion that survives the die. The zinc bonds tightly to the wire and stays ductile, so the coating does not shatter under drawing stress. Zinc loss during drawing stays in the 2-8% range — metal that remains on the wire instead of dropping into the drawing box as dust.
• One bath, several product grades. Light protective layers and the heavier deposits used for wire that will sit outdoors longer come off the same solution, so different wire products can share a line without a separate additive for each.
• Ductility through the whole downstream route. Wire that is drawn, bent or formed after plating needs a layer that moves with the steel. This deposit is formulated to keep pace with that processing rather than cracking at the first pass.
• Wide temperature tolerance, no foaming, good salt resistance. The bath keeps working as the line warms through a shift, foam does not build in the cell or the exhaust, and salt carried in with the work does not throw the solution off balance.
• A bath that holds its condition. The solution stays stable between additions, which means fewer corrections per shift and brightness that carries from coil to coil — a real advantage in a metal plating process that runs around the clock.
• Simple to run. Straightforward additions, a reading that can be taken on the floor, and no equipment beyond circulation filtration — the sort of routine a busy metal plating shop can keep to on every shift.

Specifications

Bath Make-Up Sequence

1. Dissolve the zinc sulfate (ZnSO4·7H2O) in warm water and let the sediment settle out before the solution goes into the cell — sediment carried in at make-up is a common reason a fresh mix of plating chemicals starts dull.
2. Add the brightener and the bath make-up agent to the cleared solution, stirring as you go.
3. Filter the bath before the first coil runs. Starting clean is the simplest route to a bright deposit.
4. Check the wire before it reaches the cell: no rust, no black ash on the surface. Plating over an unclean strand shows up later as patchy coverage or poor adhesion.
5. Switch on circulation filtration from the start and keep it running — a filtered solution holds an even deposit through a long plating process.

Wire Speed and Current Settings

For wire up to 1.5 mm in diameter, the published reference setting is a plated length of 16-20 m, a wire running speed of 10-30 m/min, and 400-600 A of current per individual wire.

Read the current figure per strand, not per line: a steel plating line running several wires at once multiplies it by the number of strands, and the rectifier has to carry the total. Running speed sets how long the wire stays in the bath and therefore how much zinc it picks up, so speed and current move together — change one and the other usually needs adjusting.

Those figures are published for the small-diameter case. Other diameters, higher speeds or a heavier target deposit need different values, and the right ones depend on your cell length, the number of strands and the plating chemicals already in the bath. Send us the diameter range, the speed you want to run and the coating weight you are aiming for, and we will work out a starting setting with you.

Bath Control and Consumption

• Dose by ampere-hours, not by coil count. Brightener consumption runs at 40-60 ml/KAH, so in an electro plating line the amp-hour meter is a far more reliable basis for additions than counting coils or shifts.
• A planning figure for wire output. As a general guide, producing one tonne of wire needs roughly 2,000-2,500 ml of brightener replenished. Treat it as a starting point and let your own amp-hour records refine it.
• Top up the make-up agent as well. It is lost mainly through drag-out, at around 20 ml/KAH, and it needs regular replenishment alongside the brightener or the balance shifts.
• Analyse the bath on a schedule. If you cannot run an analysis, keep the Baumé reading above 30°; that is the practical floor for a bath that is still in condition.
• Do not add other salts. Sodium sulfate (Na2SO4) and aluminium sulfate (Al2(SO4)3) are not permitted in this bath — they disturb the balance the brightener depends on.
• One input, not the whole bath. The brightener is dosed into the zinc sulfate solution you already run, so your existing zinc sulfate concentration stays the starting point; it is one of the acid zinc plating chemicals in the line rather than a replacement for the bath itself.

Operating Window and Verification

The bath is documented as working across a wide temperature range, which helps on lines without refrigeration, but the exact window for your cell depends on the deposit you need and the speed you run at. On a metal plating line where the ambient temperature swings across a shift, plan for that swing rather than for a single set point.

Cathode current density and plating time follow the same logic: both come from wire diameter, line speed and the coating weight you are aiming for. Rather than guess, plate a short sample at two or three settings and compare. Most metal plating process problems on wire lines come from a setting that was inherited rather than measured.

Agree the acceptance test before the trial. Brightness and coverage are judged visually, adhesion is usually checked by bending or drawing a length of plated wire, and coating weight can be confirmed by weighing a stripped sample. If your customer specifies a salt spray requirement, settle the method and duration with them first, so the trial is judged the same way the finished order will be — that discipline is what keeps a plating process repeatable.

Storage and Handling

• Store under cover, in the closed original container. Keep drums and boxes out of direct sun and away from frost — normal practice for metal plating chemicals — and leave the batch label in place so the material can be traced back to its lot.
• Read the SDS before the first drum is opened. Ask your sales contact for the safety data sheet and the declarations that apply in your market; those are the documents your own safety and compliance colleagues will want on file.
• Decant into clean, dedicated equipment. Use containers and measuring gear reserved for plating chemicals. Mixing residues with the make-up agent, or with another supplier's product, causes a surprising share of avoidable bath problems.
• Route rinse water and empty packaging the right way. Follow the local rules at your site and send them through the same effluent route you use for your other electro plating chemicals.

Related Products in the Range

Ordering and Delivery

• Payment: 100% T/T in advance.
• Minimum order quantity: varies by chemical; confirmed with our sales team per order.
• Lead time: 2 weeks.
• Packing: 10 kg/box; 25 kg or 50 kg/bag; 20 kg/25 kg/30 kg/200 kg/drum; 1,000 kg/IBC drum.
• Shipping: per the terms agreed in the current contract.
• After delivery: an inspection certificate is issued stating the batch number and warranty period.

Existing Bath Changeover

1. Start with the bath you already run. Send us the current zinc sulfate concentration, Baumé reading, working temperature, wire grades and line speed before the first drum goes in. SZ-75 is dosed into a sulfate bath rather than building one, so your existing zinc sulfate level stays the starting point and nothing has to be dumped to use it.
2. Correct what is already off before you dose. A bath short of zinc sulfate, or carrying oil and black ash in from pre-treatment, will plate dull whatever brightener goes into it. Fix the concentration and the cleaning stage first, then judge the additive on a sound bath.
3. Strip iron and copper before the switch. Wire lines drag iron in continuously, and the usual signs are grey or yellowish deposits, a cloudy bath and brightener consumption climbing run after run. A purification agent made for acid zinc plating baths precipitates ferrous and ferric iron without taking zinc with it and leaves little sediment, so it can go in ahead of the changeover; ask us whether it suits your analysis before you add it.
4. Check the circulation loop. The bath should run through circulation filtration with a clean housing and an unblinded cartridge, and the filter body and pump seals need to be rated for an acidic sulfate solution. A restricted loop shows up as roughness and patchy brightness along the strand, not as an obvious fault.
5. Add brightener and make-up agent as a pair. Dose SZ-75 and the make-up agent at the make-up ratio and stir thoroughly. The make-up agent is the part converters forget, because the previous system may not have used one — it covers drag-out loss, and without it the bath drifts.
6. Plate one strand as the trial. Run a short length at the speed and current you intend to use, then check brightness, coverage, adhesion by bending or drawing the sample, and coating weight by weighing a stripped piece. Compare against the criteria you agreed with your customer beforehand, not against a hunch on the floor.
7. Switch at a coil boundary, not mid-run. Do not top one brightener system up with another while both are in the tank. Either run the old bath down and change over at a coil change, or rebuild from zinc sulfate and warm water if the analysis is too far gone — the rebuild costs a shift of steel plating time but removes the guesswork.

SDS & Compliance Documents

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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