Heavy machinery and industrial equipment painting

Painting heavy machinery starts with preparation: remove the parts that get in the way, mask everything that must not be painted (machined surfaces, cylinder rods, sensors, nameplates), degrease until every trace of oil is gone, then apply a two-component system that resists oils and fluids, in the original colour. The work is done in the shop when the machine can move, and on site when it is anchored or too large.

Presses, machine tools, compressors, generator sets, conveyors, material handling equipment, construction machinery: all eventually lose their paint to oils, impacts, cleaning and corrosion. A good paint job protects the steel, makes maintenance easier and makes leaks visible. A poorly prepared one peels within months on an oily surface. This guide is for maintenance and production managers at plants in Quebec and Ontario. For mobile mining equipment, see also our article on mobile mining equipment painting.

Why does machine paint peel so often?

Machine paint most often peels because it was applied over a surface that was still oily, over an incompatible old coating, or with a product that does not resist the machine's fluids. Oil is the main enemy: even an invisible oil film prevents adhesion.

• Contamination. Hydraulic oil, grease, cutting fluid and dust work into the pores of old paint and into every recess.
• Incompatible old paint. A strong solvent over an old alkyd can lift it. Our article on painting over old coatings explains how to test it.
• Unsuitable product. An alkyd or an aerosol paint does not last long against oils, cleaning solvents or impacts.
• Heat. Housings, exhausts and areas near engines call for high-temperature coatings.

What should be removed, masked or protected?

Remove what blocks access or could be damaged, mask what must stay bare or readable, and protect what cannot take solvent or abrasive. The table summarizes the usual decisions, to be confirmed with the person responsible for maintaining the machine.

Partial disassembly is planned with the maintenance team: everything removed is tagged, photographed and stored for reassembly. Lockout of the machine comes before any work.

How is a machine degreased before painting?

A machine is degreased in two stages: heavy cleaning to remove built-up grease and dirt, then fine cleaning to remove the residual oil film. The baseline reference is SSPC-SP 1, which covers solvent and detergent cleaning before any other preparation.

1. Heavy cleaning. Scraping off deposits, hot pressure washing or steam cleaning with an alkaline degreaser, thorough rinsing.
2. Fine cleaning. Wiping with a solvent compatible with the old paint, changing rags often so oil is not spread around.
3. Check. A water-break test or a white rag wipe shows whether oil remains.
4. Drying. Recesses, welds and joints dry completely before the next step.

Degreasing is repeated after sanding or blasting if contaminants have come back to the surface.

Which surface preparation follows degreasing?

After degreasing, the surface receives mechanical preparation or abrasive blasting, depending on its condition and whether abrasive can be used. Sound old paint is sanded to give a key; rust and flaking paint are removed back to metal.

• Sound old paint. Light sanding to SSPC-SP 2 or SP 3, then dust removal.
• Local rust. Power tool cleaning to SSPC-SP 11 at rusted areas.
• Removed parts or a machine in the shop. Abrasive blasting to SSPC-SP 6 or SP 10 by our abrasive blasting service, with heavier masking.

Abrasive gets everywhere: on an assembled machine, blasting is only an option after very careful masking of bearings, slideways and openings, or after disassembly.

Which system resists oils and fluids?

A two-component system resists oils and fluids best: an epoxy primer for adhesion and corrosion protection, then a polyurethane topcoat for resistance to oils, UV and cleaning. Alkyd is simpler but suits machines exposed to fluids poorly.

• Epoxy primer. Adheres to prepared steel, sound old paint and cast iron; a surface-tolerant version helps when preparation is mechanical only.
• Polyurethane topcoat. Holds up to hydraulic oils, greases, cutting fluids and detergents, and retains colour and gloss.
• Hot zones. A high-temperature system matched to the part temperature.

Our comparison of epoxy, polyurethane and alkyd on steel details these differences. Resistance to a specific fluid is checked on the product data sheet, or by a spot test on a panel. For small removed parts, see also our comparison of powder vs liquid coating.

How are original colours matched?

Original colours are matched from the machine manufacturer's colour code, when known, or by spectrophotometer measurement on a clean, unfaded area. Gloss level matters as much as hue for a uniform look.

• Manufacturer's code. It sometimes appears in the manual or on a label; a paint supplier reproduces it in the selected system.
• Measurement. An area shielded from light, under a cover for example, gives the shade closest to the original.
• Sample. A painted panel is approved before full application.
• Safety colours. Moving parts, pinch points and stop controls follow standardized colours, as our article on industrial safety colours explains.

Should painting be done in the shop or on site?

Painting is done in the shop when the machine or its parts can be moved, because temperature, humidity, dust and blasting are easier to control there. It is done on site when the machine is anchored, too large or critical to production, with a clean work area organized around it.

On site, the job needs a marked-off zone, tarps and screens to protect neighbouring equipment, ventilation suited to solvents, no ignition sources and hours compatible with production. Brush and roller application limits drift; on-site electrostatic painting suits some metal parts. Our industrial painting service handles both modes, as part of our protective coatings work.

In both cases, the job closes with quality checks: dry film thickness measured to SSPC-PA 2 on each part, a cross-cut adhesion test to ASTM D3359 on a representative area when the specification calls for it, and a visual check of masked areas once the masking is removed. The machine is restarted only after the cure time on the data sheet, at the actual shop or plant temperature, because a paint that is dry to the touch is not yet resistant to oil. Products, batches, colour codes and readings are recorded, so the next touch-up uses exactly the same system and colour.

Frequently asked questions

Can a machine be painted without disassembly?

Yes, with thorough degreasing, careful masking and mechanical preparation. Removing covers and guards is still advisable to reach hidden faces.

Which paint resists hydraulic oil?

A two-component system, usually an epoxy primer and a polyurethane topcoat. Resistance to a specific fluid is confirmed on the data sheet.

How long is the machine out of service?

It depends on size, disassembly, preparation and the drying and curing times of the system. The schedule is set in the quote.

Can the original colour be reproduced exactly?

Yes, in most cases, from the manufacturer's code or a spectrophotometer reading, with a test panel approved before application.

Our crews and qualified subcontractors paint machinery in the shop or on site, working from LaSalle, including in Montérégie and Laval. Send photos of the machine, its dimensions, the fluids in contact and the desired colour through the quote request: pricing on consultation, reply within 24 business hours.