Marking Spray & Powder | Buying Guide

CO2 lasers can’t directly engrave bare metals such as stainless steel, brass, copper, or aluminum. To mark these surfaces, you need a laser marking compound—a specialty coating that reacts under laser heat to create a durable, high-contrast mark. These compounds typically come in two formats: spray and powder. Both can deliver reliable marks, but they differ in how you apply them and the level of control they offer.

In this guide, you’ll learn why marking compounds are essential for CO2 metal marking, and how to choose between spray and powder based on your workflow.

Why Laser Marking Compound Works for CO2 Lasers on Metals

CO2 Laser Wavelength and Metal Reflection

CO2 lasers emit light at roughly 10.6 micrometers (10,600 nm), which sits in the far-infrared range.

Bare metals like stainless steel, brass, copper, and aluminum reflect a large portion of energy at this wavelength. As a result, when a CO2 beam hits untreated metal, most energy reflects instead of being absorbed. That prevents the surface from heating enough for direct etching, engraving, or marking.

The Role of Marking Compounds

Laser marking sprays and powders use purpose-built chemical formulations that do two key jobs:

• Absorb the CO2 laser wavelength: Unlike bare metal, the compound is engineered to absorb the CO2 laser’s 10.6 µm energy efficiently.

• React under heat and bond to metal: After absorbing energy, the coating heats rapidly and triggers a reaction within the compound and at the metal surface, permanently fusing the mark to the metal. The result is typically a durable, high-contrast black mark.

In other words, the marking compound acts as the “interface” between a CO2 laser and reflective metal, converting laser energy into a permanent bonded mark.

How to Choose the Right Laser Marking Compound

When choosing a marking compound, consider the factors below to get consistent, professional results.

1. Cost Considerations

Spray: Marking sprays are ready to use—no extra tools or mixing agents (like alcohol) required—so setup is straightforward.

Powder: Marking powders must be mixed with alcohol, which you’ll need to purchase separately. That said, in terms of cost per application, OMTech spray and powder options are broadly comparable.

2. Production Volume & Application

For low to medium volume or occasional use: If you’re running small batches, making one-offs, or marking metal only from time to time, spray is usually the most convenient choice. With no prep work, you can start quickly—ideal when speed and simplicity matter. Even though per-use cost is similar to powder, the ready-to-spray format is often a better fit here.

For high volume or continuous production: For larger, high-throughput workflows, spray is still a strong recommendation. Fast, consistent application helps reduce handling time and keeps production moving—especially when you’re marking many parts daily.

For large items: Spray is strongly preferred for large surfaces. Aerosol application makes it easier to cover big areas quickly and evenly, while powder can be harder to spread uniformly at scale and may take more effort.

For small items: Both spray and powder perform well on smaller parts. Powder can be brushed on after mixing, while spray is often faster and cleaner when convenience is the priority.

3. Application Method & Control

Ease and speed of application: Spray offers the quickest, most user-friendly workflow because it applies directly from the can. This is especially helpful for small parts or irregular shapes.

Precision and uniformity: With experience, spray can deliver even coverage, but powder offers more control. When mixed and applied with an airbrush or HVLP spray gun, powder supports finer adjustment of coat thickness and uniformity—useful for large, flat parts or jobs where repeatability is critical. For small, targeted zones, brushing powder can also provide excellent control.

Customization of consistency: Powder lets you tune the mixture by adjusting the powder-to-alcohol ratio, which can affect dry time and final mark quality depending on the metal. For best results, we recommend mixing with 99% anhydrous alcohol. Sprays arrive pre-mixed at a fixed consistency, which is convenient but less adjustable.

4. Workspace Environment & Cleanup

Fumes and ventilation: Adequate ventilation is required for both methods. Laser marking produces fumes from the compound and sometimes from the metal surface. Sprays add solvents/propellants during application, while powder mixtures release alcohol vapors—especially when using 99% anhydrous alcohol.

Mess and containment: Sprays can create overspray, so it’s best to use a controlled spray area and protect nearby surfaces. Powders—especially when mixed and brushed—often generate fewer airborne particles and can be easier to contain, though mixing can still create localized mess. After marking, removing leftover residue is generally similar for both methods.

5. Storage

Spray is sealed in a high-pressure aerosol can, which is easy to store. If stored properly and the nozzle stays clear, the can typically remains usable over time.

Powder should be stored dry. After mixing with alcohol, keep the mixture in an airtight container to prevent evaporation and moisture contamination.

For longer shelf life, use high-purity alcohol (ideally 99% anhydrous) and reseal the container tightly after every use.

If the solution turns green, it’s usually a mild reaction between the powder and water present in lower-purity alcohol. Our testing shows little impact on performance, although it may cause slight staining on copper.

If the mixture thickens over time, add small amounts of alcohol to return it to the desired viscosity. Remember: alcohol doesn’t create the mark—it’s only the carrier. For best results, apply a thin, even layer that just masks the base metal color.

General Recommendation

We developed laser marking powder primarily to avoid high-pressure gases and flammable components, not to reduce cost. As a result, powder is often easier to ship and is less likely to face hazmat-related restrictions—an important advantage for international or regulated shipments.

If shipping constraints aren’t an issue, spray is generally the easiest recommendation. It’s simpler to store, faster to apply, and tends to produce a more consistent, even coating—especially helpful for first-time users or anyone who wants quick, repeatable results.

No matter which option you choose, run test marks on scrap first. Adjust laser parameters (power, speed, frequency, LPI) and coating thickness to dial in the best results for your specific metal and marking requirements.