How much zinc a job actually takes — and an honest separation between the part that is arithmetic and the part that is your own plant's experience.
The zinc that ends up on the steel is exact arithmetic. Surface area times coating mass. At 7.14 g/m² per micron, 100 m² at 85 microns is 60.7 kg of zinc on the work, and no estimate is involved.
The zinc a bath actually consumes is not. Dross forms at the bottom, ash forms at the top, and every piece carries some zinc out that never becomes coating. That loss depends on the work mix, bath management and skimming practice — it is a plant-specific figure, and any supplier quoting a universal one is guessing.
So this calculator gives you the hard number and lets you apply your own multiplier. We have not baked one in.
Coating zinc is arithmetic. Bath zinc is coating zinc plus everything the process loses — dross, ash and drag-out. The multiplier below is yours to set from your own records; we do not publish one as if it were universal.
Set the multiplier to 1.00 and you get the zinc that ends up on the steel — a hard number. Anything above 1.00 is your own plant's loss factor, and it varies with work mix, bath management and how much dross you skim. Do not borrow someone else's.
| Loss | What it is | Roughly influenced by |
|---|---|---|
| Dross | Zinc-iron intermetallic that sinks to the bottom of the kettle | Iron pickup from the work and the kettle, bath temperature, immersion time |
| Ash | Oxidised zinc skimmed from the surface | Surface disturbance, how often work enters and leaves, flux carry-over |
| Drag-out | Zinc that leaves on the work but is not coating — runs, spikes, tears | Withdrawal rate, drainage, venting and hanging |
| Coating itself | The zinc that does the job | Steel chemistry — especially silicon — and immersion time |
The last row is worth noting: steel chemistry changes coating thickness. Silicon content in particular drives the growth of the zinc-iron alloy layers, so two consignments dipped identically can come out at different thicknesses. That is a real effect, not a process fault.
Then this page is mainly useful for sanity-checking a quotation. Galvanizing is normally priced by weight of steel or by area, and knowing the zinc content of your own job tells you quickly whether a rate is plausible.
We galvanize on our own line at Jangalpur, Howrah — a 7.0 m × 1.2 m × 1.6 m kettle at 450–460 °C — and we accept job work from fabricators, OEMs and project contractors across Kolkata and eastern India. Send the drawing or the bill of material and we will quote against it.
Answered from our own line, not from the standard's cover page.
The coating itself is exact: at 7.14 g/m² per micron, an 85 micron coating is 607 g of zinc per square metre, or about 0.61 kg. Total bath consumption is higher because of dross, ash and drag-out, and that additional fraction is specific to the plant.
Because there is no honest universal figure. Losses depend on work mix, bath temperature, immersion and withdrawal practice and how the kettle is skimmed. We would rather give you the arithmetic and let you apply your own multiplier than publish a number that looks authoritative and is not.
Yes, materially. Silicon content in the steel drives the growth of the zinc-iron alloy layers, so two consignments dipped under identical conditions can come out at different coating thicknesses. It is a real metallurgical effect rather than a process fault.
Use our steel section weight calculator — it gives surface area alongside weight for plate, bar, angle, pipe and hollow sections. Then add area for cleats, gussets and base plates, which a bill of material will not show.
Send the drawing or the bill of material and we will tell you plainly how the job is priced and what the turnaround looks like. Galvanizing here is in-house, so the answer comes from us rather than from a sub-contractor's queue.
Tell us the standard, the coating requirement and the component, and we will confirm in writing what we can hold and how we will certify it. Galvanizing is on our own floor, so the answer comes from us and not from a sub-contractor.
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