Visual reference

Defect & Appearance Gallery

Everyone can describe a galvanizing defect. The question that actually decides the job is different: do you accept it, repair it, or reject it? Every entry here answers that against ASTM A123 and ISO 1461 — from real plant photos, not renders.

Close-up of a galvanized beam surface scattered with small raised dross pimples in the zinc coating

REJECT IF GROSS

Dross Inclusions

Hard, gritty particles felt and seen in or under the coating.

Galvanized beam photographed from below: a broad chalky grey-white ash deposit spreads across the web with soft feathered edges, clearly lighter than the sound zinc beside it, and the same deposit continues as a dark band under the top flange where it falls into shadow

ACCEPT AFTER CLEANING

Ash Inclusions

Dull grey-white deposits or streaks on the surface.

Galvanized steel tubes stacked on a rack: elongated black bare patches run along the upper face of the nearest tube where the zinc never took, with sound bright coating surrounding each patch

REPAIRABLE

Bare Spots (Uncoated Areas)

Exposed steel with no zinc — from pinhead spots to patches.

Galvanized channel section with white powdery wet-storage stain deposits spread across the face around drilled holes

ACCEPT AFTER CLEANING

Wet-Storage Stain (White Rust)

White to grey powdery deposit, from light film to bulky build-up, typically where surfaces were stacked in contact.

Close-up of a galvanized fillet weld corner: a broad translucent yellow-ochre flux film lies across the flange face with fine white crystalline speckles through it, while the weld bead itself is fully galvanized with its ripples clearly visible under sound zinc

REPAIRABLE

Flux Inclusions & Flux Staining

Two modes, and they are not equally serious.

Galvanized gusset and base-plate connection: a brown crusty slag ridge runs along the weld toes with no zinc on it, rust stain bleeds onto the coating below, and round weld spatter nodules are scattered across the gusset face

REPAIRABLE

Uncleaned Welding Slag & Spatter

A hard crusty ridge tracing the weld toe with no zinc on it, rusting brown and bleeding stain onto the sound coating either side.

Two galvanized steel sections photographed after being separated: each carries a dull grey contact patch with straight edges where the pieces were stuck together in the zinc bath, against otherwise bright coating

REPAIRABLE

Articles Stuck Together / Contact Marks

Dull grey patches with straight, geometric edges that match the footprint of another piece — and the same mark appears on both mating faces.

Internal corner of a galvanized steel fabrication: a thick lumpy mass of solidified zinc has pooled on the horizontal gusset plate, which has no drain hole, while the surrounding faces carry bright normal coating

Lumps, Runs & Drainage Spikes

Thick pooling of solidified zinc that could not drain, accumulated in corners, on gussets and inside sections.

Large galvanized pipe bend with a flange: the elbow shows a dull matte grey coating while the adjoining straight pipe shows bright spangle, in the same assembly

Matte Grey / Dull Coating

Uniform or patchy dark grey, matte surface — no bright spangle.

Wide galvanized panel with scattered raised blisters erupting through the coating, their pale broken crowns standing out against the smooth darker zinc surface

REJECT

Blisters & Pimples

Small raised bumps or blisters in the coating, intact when probed or occasionally hollow.

Galvanized bar welded into a base plate: translucent amber liquor weeps from the joint crevice and spreads over the surrounding sound coating, with darker crusted residue at the gap itself

NOT A COATING DEFECT

Rust Bleed / Weep Staining

Staining that runs from a joint onto sound coating.

Galvanized tubular section photographed close up: a coarse granular coating texture shows along the band of raking light, with no isolated lumps or inclusions

General Roughness

Uniformly coarse, textured coating over large areas rather than isolated particles.

Thin galvanized steel plates hanging on wires after the kettle, buckled into deep S-curves and waves along their length while the zinc coating on them stays bright and sound

NOT A COATING DEFECT

Distortion & Warpage

Members bowed, twisted, or panels oil-canned after galvanizing — plus a third mode that catches people out: the assembly stays straight but a joint lets go.

Galvanized bracket with a grey-green zinc-rich paint repair applied around a drilled hole, with a paint run visible below it

Touch-Up & Repaired Areas

Grey-green zinc-rich paint patches, bright soldered areas, or matte metallized zones within the surrounding hot-dip coating.

A handheld coating-thickness gauge held probe-down against a bright galvanized folded steel section, its display reading 39.2 — the coating looks completely normal to the eye

REJECT

Low Coating Thickness

None.

Galvanized surface where the bright free zinc has flaked away across the centre, exposing the darker smooth zinc-iron alloy layer beneath, with the remaining zinc surviving around the edges as chalky islands with jagged boundaries

REJECT

Zinc Flaking / Poor Adhesion

Flat patches where the bright free zinc has come away and left the darker, duller zinc-iron alloy layer showing beneath.