Cold Galvanizing & Metallizing

When hot-dip is not an option, and what we treat

Hot-dip galvanizing is a plant process: the steel is dipped in a bath of molten zinc. It becomes impossible or pointless in five cases, and that is where zinc protection applied on site takes over:

• The part is installed: a walkway, frame, conveyor or handrail in service that is not coming down.
• The part is too large or too heavy for the kettle or for shipping.
• The schedule does not allow a round trip to the galvanizer.
• A field weld, cut or drilled hole has exposed bare steel on a galvanized part.
• The original galvanizing has worn away, for example on a galvanized steel roof or a structure exposed to de-icing salts, and needs to be rebuilt.

We do not do hot-dip galvanizing. If your part is new, can be removed and the schedule allows, the bath is often still the better choice, and we will tell you so. Cold galvanizing and metallizing are part of our protective coatings work, alongside epoxy and polyurethane systems.

The assets we treat most often:

• Walkways, grating, stairs and handrails, often galvanized originally and repaired after modifications.
• Galvanized steel roofs and cladding where the zinc is used up and rust is showing.
• Steel structures and frames, pipe supports, towers and process buildings (corrosion protection).
• Conveyors: frames, galleries, trestles and runway beams.
• Marine and port equipment: wharves, bollards, fenders, and structures in the splash zone, where thermal spray aluminum is often preferred.
• Field welds and cuts on new galvanized parts, before they go into service.

The service is for industrial sites only: no residential work, garages or house fences. Work is carried out by our crews and qualified subcontractors.

Three options and how to choose

Three methods put zinc or aluminum on steel in place. They are not interchangeable: the choice depends on exposure, area and access.

• Zinc-rich primer or coating (cold galvanizing): a paint whose pigment is zinc dust, in an epoxy or silicate binder. The particles in contact with the steel protect it galvanically (zinc-rich primer). A cold galvanizing compound goes on by spray, roller or brush, over large or small areas.
• Thermal spray metallizing: zinc, zinc-aluminum or aluminum wire is melted by electric arc or flame and sprayed onto blast-cleaned steel. The result is a layer of pure metal with no binder, the closest field equivalent to hot-dip galvanizing (thermal spray aluminum).
• Galvanizing repair to ASTM A780: repair of damaged or uncoated areas on hot-dip galvanized parts, using zinc-rich paint, zinc-based solder or sprayed zinc.

Decision guide, in short:

• Spot repair on new galvanizing (weld, cut, scratch): ASTM A780 repair.
• Steel in place, moderate atmospheric exposure, tight budget: zinc-rich primer, then intermediate and topcoat.
• Severe exposure (ISO 12944 categories C5 or CX), salt spray, de-icing salts, long service wanted without removal: zinc or zinc-aluminum metallizing, plus sealer.
• Seawater, splash zone, hot steel or steel under insulation: thermal spray aluminum, plus sealer.
• New part, removable, schedule available: hot-dip galvanizing at a plant.

Required surface preparation

Cold galvanizing over rust does not work: zinc must touch bare steel to protect it. Applied over rust or mill scale, it is just grey paint that will let go. Preparation is set in the quote, method by method.

• Metallizing: abrasive blasting to SSPC-SP 10 (near-white) for atmospheric exposure, or SSPC-SP 5 (white metal) for immersion and the most severe environments, with a sharp angular profile (NACE No. 2 / SSPC-SP 10 guide). Spraying follows blasting without delay, before any flash rust.
• Zinc-rich primer: blasting to the grade on the product data sheet, generally SSPC-SP 10 for zinc systems.
• ASTM A780 repairs: power tool cleaning to bare metal per SSPC-SP 11 where blasting is not possible, over the damaged area and a band of sound galvanizing around it (SSPC-SP 11 power tool cleaning).

Restoring a galvanized roof or structure also calls for degreasing and removal of white zinc salts before anything is applied. On galvanized steel that is still sound and is to be painted, a light sweep blast per SSPC-SP 16 provides the anchor the paint needs.

Sealer, topcoat and how the job runs

Metallizing is always sealed: the sprayed layer is porous, and the sealer closes those pores before moisture settles in. A topcoat may follow for colour or chemical resistance, which makes it a duplex system. A zinc-rich primer also gets an intermediate and topcoat once the exposure goes beyond a dry interior, according to ISO 12944.

The job follows six steps:

• Survey: condition of the existing galvanizing or paint, areas, access, operating constraints.
• Technical quote: selected method, preparation grade, target thicknesses from the standard or data sheet, inspections and exclusions.
• Preparation: protection of adjacent equipment, degreasing, blasting or power tool cleaning.
• Application: metallizing, zinc primer or repair, with dew point, relative humidity and substrate temperature monitored.
• Sealer and topcoat, within the planned recoat window.
• Records: conditions, thicknesses, adhesion tests, batch numbers and photos.

Inspections and standards

Every coat is measured and recorded. The inspections and reference standards are:

• Thickness: magnetic gauge measurement per SSPC-PA 2, on the metallizing, the primer and the full system (dry film thickness).
• Adhesion: pull-off testing per ASTM D4541, at the frequency set by the specification.
• ASTM A780: methods for repairing damaged and uncoated areas of hot-dip galvanized steel.
• SSPC-CS 23.00 / AWS C2.23: thermal spraying of zinc, aluminum and their alloys for corrosion protection of steel, from preparation to inspection.
• ISO 2063: thermal spraying of zinc, aluminum and their alloys, requirements and testing.
• ISO 12944: corrosivity categories and paint system selection, sealer and topcoat included.

Zinc behaves differently depending on the metals it touches. In contact with copper, stainless steel or other more noble metals, it is consumed faster: check our galvanic series table before joining dissimilar metals.

Site conditions and safety

Metallizing and blasting are done under site-specific safety measures, settled in the quote:

• Metal fumes: spraying gives off zinc or aluminum fumes. Ventilation, extraction and respiratory protection are mandatory, especially in confined spaces.
• Hot work: arc and flame spraying require a hot work permit and removal of combustible materials.
• Work at height: scaffolding, lifts or rope access for walkways, roofs and structures.
• Containment: tarps and enclosures to hold abrasive and overspray, particularly near water on port sites.
• Winter: steel must stay above the dew point during preparation and spraying, which often calls for a heated enclosure.
• Operating plant or planned shutdown: work by zones, coordinated with operations.

Pricing: by quote

Cold galvanizing and metallizing are priced by quote. The cost depends on these factors:

• The method: repair, zinc-rich primer or metallizing, and the metal sprayed.
• The area and shape of the parts: grating or a lattice frame takes longer than flat plate.
• The preparation grade and the condition of the substrate: rust, old paint, zinc salts.
• Access, height and the containment required.
• The planned sealer and topcoat, and the work window.

Send photos, approximate dimensions and the location with your quote request: we reply within 24 business hours.

Where we work

Induscoat provides on-site cold galvanizing and metallizing across Quebec and in Ontario, working from LaSalle:

• Montreal and Montérégie
• Quebec, for the province as a whole
• Abitibi-Témiscamingue
• Côte-Nord
• Saguenay–Lac-Saint-Jean
• Mauricie–Centre-du-Québec
• Ontario

When this service is not the right answer

Zinc protects steel in atmospheric exposure and in water, not in chemicals. For an acid or alkaline solution tank, a process vessel or a spill area, a barrier lining such as novolac epoxy is needed: see our protective coatings and tank lining.

If blasting reveals thinned plate, deep pitting or attacked welds, no zinc layer restores the strength that is gone. The repair starts with our maintenance and rehabilitation service. And for a simple repaint of a structure whose paint is still well bonded, industrial painting is often enough.

Typical Problems We Solve

• Parts too large, installed or urgent to send to a hot-dip galvanizer
• Bare steel at field welds, cuts and drilled holes on galvanized parts
• Worn galvanizing with rust showing on roofs and structures exposed to de-icing salts
• Cold galvanizing compound applied over rust that peeled without protecting the steel

What You Receive

• Technical quote stating the method, the metal or primer, the preparation grade and the planned inspections
• Steel prepared to SSPC-SP 10, SP 5 or SP 11 as specified, then metallized, primed or repaired
• Thickness readings per SSPC-PA 2 and adhesion tests per ASTM D4541 on record
• Close-out file with ambient conditions, batch numbers, sealer and topcoat data, and photos

Timeline

Standards & Certifications

• ASTM A780: repair of damaged and uncoated areas of hot-dip galvanized coatings
• SSPC-CS 23.00 / AWS C2.23: thermal spraying of zinc, aluminum and their alloys on steel
• ISO 2063: thermal spraying of zinc, aluminium and their alloys
• ISO 12944: corrosivity categories and protective paint system selection

Industries We Serve

• Mining: conveyors, walkways, concentrator structures
• Ports and marine: wharves, fenders, splash zone structures
• Energy: steel structures, towers, galvanized walkways and stairs
• Steel, metallurgy and processing: process buildings, galvanized roofs, pipe racks

Service FAQ

Technical guides

• Galvanic series: metal compatibility
• ISO 12944: corrosivity categories and system selection
• NACE No. 2 / SSPC-SP 10 surface preparation
• Power tool cleaning: SSPC-SP 3, SP 11 and SP 15
• Maintenance painting of steel structures

Related applications

Concrete industrial use cases where this service is applied.