Comparison between G90 galvanized steel and galvanneal steel for laser cutting

Galvanized (G90) vs galvanneal steel

Both materials start from the same carbon steel meeting the ASTM A653 standard, protected by zinc. The difference is in how the coating is treated — and it completely changes what each sheet is meant for. Here's how to decide before requesting a quote.

The short answer

Your part stays as-is, unpainted (ductwork, bracket, utility part) : choose G90 galvanized steel. Your part will be powder coated (enclosure, panel, cover) : choose galvanneal steel — it's also the only one of the two offered with powder coating at Laseo.

What is G90 galvanized steel?

A carbon steel sheet coated with pure zinc by hot dipping. The "G90" designation indicates the weight of zinc deposited under the ASTM A653 standard — it's a generous coating, designed so the part resists corrosion without any further treatment.

Its surface is shiny, with the flecked pattern (the "zinc spangle") typical of galvanized steel. It's the default choice when the part will be exposed to moisture and left bare.

Full spec sheet : G90 galvanized steel

What is galvanneal steel?

The same steel galvanized to ASTM A653, but annealed after galvanizing. The trip through the furnace lets iron diffuse into the zinc layer, creating an iron-zinc alloy at the surface. The result : a matte, uniform gray finish, with no spangle.

This matte, slightly rough surface is exactly what paint is looking for : it grips far better than the smooth, shiny zinc of G90. Galvanneal is sold as a "paint-ready" steel — its bare protection is more modest than that of G90.

Full spec sheet : galvanneal steel

Side-by-side comparison

Mechanically, the two sheets are twins : same base steel, same strength properties, same fiber laser cutting tolerance (± 0.005″) at Laseo. Everything comes down to the coating and the treatments offered afterward.

Criterion G90 galvanized Galvanneal
CoatingPure zinc, hot-dippedIron-zinc alloy (annealed after galvanizing)
AppearanceShiny, spangledMatte gray, uniform
Protection without paintSuperior — designed to stay bareAdequate, but meant to be painted
Paint adhesionWeak on the smooth zincExcellent — matte surface that grips
Powder coating at LaseoNot offeredOffered on all thicknesses
WeldabilityMore spatter and zinc fumesBetter — less free zinc at the surface
StandardASTM A653 G90 CS Type AASTM A653 (galvannealed)
Tensile strength58–65 ksi58–65 ksi (identical)
Yield strength46 ksi46 ksi (identical)
Magnetic / rusts if scoredYes / yesYes / yes

Which thicknesses are in stock at Laseo?

The two ranges overlap from 22 to 12 gauge. Only G90 is offered in 24 gauge (the thinnest), and only galvanneal goes up to 11 gauge (the thickest).

Gauge Thickness Weight G90 galvanized Galvanneal
24 gauge0.028″1.127 lb/ft²✓—
22 gauge0.034″1.372 lb/ft²✓✓
18 gauge0.052″2.107 lb/ft²✓✓
16 gauge0.064″2.593 lb/ft²✓✓
14 gauge0.079″3.205 lb/ft²✓✓
12 gauge0.108″4.426 lb/ft²✓✓
11 gauge0.123″4.884 lb/ft²—✓

Both are cut on the fiber laser and bend on all thicknesses (see the bending service). Tapping is offered in 16 and 14 gauge for both materials. One difference to note : hardware insertion is offered on G90 (18 gauge and up), but not on galvanneal.

Why does galvanneal take paint better than G90?

The pure zinc of G90 is smooth and slightly oily fresh from the mill — paint adheres to it poorly and eventually flakes off, especially on bends and edges. The iron-zinc surface of galvanneal, on the other hand, is matte and microporous : the powder anchors to it mechanically and the conversion coating forms without an aggressive prep step.

That's why at Laseo, powder coating is offered on galvanneal in all its thicknesses, but not on G90 galvanized. You get the best of both worlds : the zinc protecting the steel underneath, and the powder sealing it and providing the color.

And where does mild steel fit in? If the part will live indoors and dry, a powder-coated mild steel part is generally cheaper than galvanneal — but with no zinc, a scratch down to the metal will eventually rust. For outdoor or humid environments, the galvanneal + powder duo remains the most durable choice.

Which one welds best?

Galvanneal. The iron-zinc layer of galvanneal contains less free zinc at the surface than G90 : welding produces less spatter, less porosity in the bead and fewer zinc fumes — a real advantage if your cut parts then go to your welder.

G90 welds too, but the pure zinc that vaporizes at the arc calls for more cleanup and better ventilation. In both cases, plan for a protective touch-up (zinc-rich paint) over the welded zone, since the coating is burned off locally there.

Verdict by application

Application Our verdict Why
Ductwork and HVAC componentsG90 galvanizedStays bare, thick zinc, the industry standard
Unpainted outdoor brackets and anglesG90 galvanizedBetter protection with no additional treatment
Powder-coated electrical enclosures and panelsGalvannealSuperior adhesion; the only one offered with powder at Laseo
Painted trailer parts and fendersGalvannealZinc + powder = double barrier against road salt
Welded assembliesGalvannealLess spatter and fewer zinc fumes at the arc
Parts with inserted hardware (PEM)G90 galvanizedInsertion offered on G90 only (18 gauge and up)
Thin sheet (24 gauge)G90 galvanizedOnly one offered in 0.028″
Thick sheet (11 gauge)GalvannealOnly one offered in 0.123″
Indoor, dry, painted part on a tight budgetMild steel + powderMore economical option when zinc isn't required

Still undecided? Upload your drawing and compare the two materials directly in our app — the relative price and available operations show up for each thickness. Or write to us at info@laseo.ca with a photo of the environment the part will live in : we'll get back to you with a clear recommendation.

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