Frequently asked questions

Only where the reason for not galvanizing is geometry, transport or site access — components too large for a bath, welds that only exist after erection, repairs to galvanized steel in service. Cold spray zinc is a physically bonded coating with sacrificial protection, not a metallurgically alloyed zinc-iron layer: for mass-produced standard components that fit a bath, hot-dip remains cheaper and more durable per square metre.

It is the zinc fraction by weight in the cured film, and it governs two things: whether zinc particles stay in contact with each other (a continuous conductive path) and how much sacrificial capacity a given film thickness carries. Below roughly 85% the particles are no longer reliably in contact and cathodic protection drops off sharply; around 96% the layer behaves close to a zinc coating rather than a paint.

Typically 40–60 µm wet-on-dry per pass; reaching 80 µm is normally two passes. Trying to build 80 µm in a single heavy pass is the most common cause of mud cracking and adhesion loss, because the solvent has to escape through an already dense zinc-rich film. Where the TDS allows a higher single-coat build, it also specifies a longer interval before recoating.

Sa 2.5 to ISO 8501-1 with a 40–75 µm angular profile to ISO 8503-1 for immersion, C5-M and long-life work. St 3 by power tool is acceptable for touch-up and repair, but expect a shorter service life and a lower film build — and say so to the client in writing rather than letting the number stand alone.

Within four hours under normal conditions — sooner in humid or marine air. Past that window the steel has already begun to flash-rust and the profile is partly filled with oxide; the correct response is to re-blast, not to paint over it. Painting over a rusted profile is the single most common cause of early blistering that gets blamed on the product.

No. Zinc vaporises at welding temperature and causes porosity and embrittlement in the weld, and the layer within roughly 100 mm of the arc is destroyed anyway. Strip the coating back before welding, weld, then restore the area with the same product — including the heat-affected zone, which needs preparation as if it were new steel.

Typically a few hours at 20 °C, and always per the TDS for the actual substrate temperature — the interval roughly doubles for every 10 °C drop. If the maximum interval is exceeded the surface must be abraded to restore key before recoating; a topcoat applied onto a fully cured, glossy zinc surface will not bond, and that failure appears months later as peeling.

The usual limits are steel temperature at least 5 °C and at least 3 °C above dew point, and relative humidity no higher than 85%. Below that, cure slows to the point where the next coat cannot be applied within its window, and moisture condensing on the fresh film causes amine blush or loss of adhesion. Heat the steel or dehumidify the space; do not simply extend the interval and hope.

Exposed to atmosphere at 60–80 µm it behaves broadly like galvanizing of similar thickness and dulls to the same grey basic zinc carbonate film; the life is then a function of the corrosivity category and the local deposition rate. In immersion, in splash zones, or where the C5-M/CX design life must be certified, it is used as a base within a full system — 240 µm and above, per ISO 12944 — not as a standalone finish.

Zinc-rich epoxy is two-component, usually 70–80% zinc, and depends on a full system above it; it is the right choice for new steel inside a specification. Cold spray zinc is single-component, higher in zinc, and can be used alone or as a base — its advantage is in repairs, on galvanized surfaces, and wherever mixing two components on site is the thing most likely to go wrong.

Supplied in pails and drums with the size confirmed per order, in UN-approved packaging and declared as UN 1263 Class 3 for sea freight. Shelf life is stated on the TDS and counted from the production date on the label; keep containers closed, out of frost and out of direct sun. Buyers must hold any import registration their own country requires — we supply the MSDS on request and the UN packaging certificate, not the import licence.

TDS and the full parameter sheet for each of the seven grades are downloadable from the TDS library on this site in five languages. MSDS, batch inspection report, salt-spray test reports and the plant's quality-system certificate are not published for download - request them and we send the current edition, normally within one working day. For sea freight, the dangerous goods declaration and UN packaging certificate are issued with the shipment; sample quantities can be arranged before an order is placed.