Laser Engraving Granite: Expert Guide

Laser Engraving Granite: Expert Guide

Laser Engraving Granite: Expert Guide

Laser engraving can be used to customize granite with designs, text, or images that can last a lifetime.

Despite its toughness, granite can be engraved easily, provided you maintain good process control.

This article discusses the process of laser engraving granite and its applications.

I also discuss the factors that affect the engraving quality.

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Laser Engraving Granite- The Process

Laser engraving on granite can be performed by using a moderately powerful CO2 laser (above 60W). Generally, polished granites are used for laser engraving because the laser removes their shiny-polished surface, revealing the dull layer underneath. Furthermore, black granites produce the ideal results with high contrast gray-white engravings.

The process of laser engraving granite consists of a few basic steps.

ParameterRecommendation
Type of laserCO2
Laser power40W and above
Engraving SpeedHigh-speed multi-layer engraving
Spot size0.25mm - 0.5 mm diameter
Air assistA low-pressure air assist is recommended
Exhaust systemRequired to effectively remove the dust

Recommended parameters for laser engraving Granite

Optimizing the Design

The first step in laser engraving granite is to prepare the design. You can use any standard CAD software like Adobe Illustrator, Inkscape, CorelDRAW, etc.

For granite engraving applications, it is recommended to limit the image data to the important parts. It can be a person in the image or any other object.

This can be achieved by following the below-given steps to customize the design.

Steps:

  1. Remove the unnecessary background
  2. Increase the image contrast
  3. Covert the image to grayscale
  4. Invert color to make it a negative image
  5. Adjust the contrast
  6. Make final adjustments
  7. Export the final image
CAD process in engraving granite - Grayscaled image (left), Backgrounds removed (middle), Negative image (right)
CAD process in engraving granite - Grayscaled image (left), Backgrounds removed (middle), Negative image (right)

Inverting the color to produce a negative image is generally used when engraving dark granites.

Laser engraving on black granites produces a high-contrast white mark with a black background, which resembles closely a negative image.

In most other laser engraving applications, like laser engraving wood, we work on light-colored objects where black engravings are produced. In such applications, inverted images are not needed.

Engraving

To run the job, you can use laser control software like LaserGRBL, LightBurn, OpenBuilds CONTROL, LaserWeb, etc.

Make sure the work area of your laser machine can handle the weight of the granite slab before placing it.

If you are working on large blocks of granite thicker than 2", it is advised to use an independent leveling system that can carry large weights and level the workpiece perpendicular to the laser beam path.

Clean the granite surface to remove any pre-existing stone dust, as it can reduce the intensity of the laser beam reaching the granite surface.

Multi-layer engraving gives better details on granite as you can engrave important texts and shapes comparatively deeper than the rest of the engraving, by using the multi-pass technique.

A laser spot size between 0.25mm to 0.5 mm in diameter is a good option for performing engraving operations on granite.

Also, a low-pressure air assist with the support of an exhaust can help effectively remove the generated dust from the workpiece surface during the job.

Laser Power
(Watt)
Output Power
(Percentage)
Speed
(ipm)
No. of Passes
40W85%238.5 ipm1
60W85%283.4 ipm1
65W40%649 ipm1
80W85%354.3 ipm1
100W25%649 ipm1
150W18%649 ipm1

Speeds and Feeds chart of engraving granite using a CO2 laser

Post-Processing

After completing the engraving process, the granite slab will be covered in dust, and you have to clean it off first.

Then you can give it a chemical wash using denatured alcohol to remove fine dust particles trapped inside the engrave-trench.

You can also use other cleaning fluids, like denatured alcohol, that dissipates quickly, making the surface ready for further processing.

After cleaning the surface, you can apply a layer of paint all over the engraved part to highlight your engraving.

The rough, porous nature of the engraved granite surface facilitates the bonding of paint to the granite surface.

Laser Engraving Granite - Factors to Consider

Color - Black is Better

Black galaxy granite
Black galaxy granite (Source: International Granites)

Black granites are generally used for laser engraving because the engravings on them will have a highlighted look.

Special laser-grade super black tiles, which are generally priced a little higher compared to the regular black granite, are ideal for different types of laser engraving applications.

However, you can also use regular general-purpose granite, like black galaxy granite, that has a fine grain structure and produces high quality engraving outputs.

Grain (Fine grains = Great Details)

Granite grains (Source: Marble and Granite Connection)

When selecting granite for laser engraving applications, it is recommended to choose one with fine grains.

Rough grains of a granite interfere with the engraving design and reduce the detail in the engraving.

Fossils/Veins

Granite veins (Source: Texas Granite Group)

Fossil bugs and vein whites in granite can negatively influence the details in an engraving.

Some granite have hair-thin trails, while others have trails over a broader area.

These generally have an irregular appearance, and it is recommended to choose granite that does not have any visible fossils or veins.

Composition

Granite is mainly composed of quartz (10% to 60% by volume) and feldspar.

If you are engraving granite for outdoor applications, choose one with a higher quartz content as they are hard and durable.

Surface Finish

Black Zimbabwe polished granite
Black Zimbabwe polished granite (Source: Southland Stone)

As a general rule, stones with smooth or polished surfaces give good results when laser engraved.

When selecting the granite for your application, it is advised to look for granite with a smooth surface finish, as it produces high-quality engraving results and makes your post-processing process much more manageable.

Laser Type and Power

CO2 lasers with a power rating of above 40W can be used for laser engraving granite.

However, a 60W CO2 laser gives much more flexibility in the variety of granites you can process.

Applications of Laser Engraved Granite

Granite is used in many applications because of its natural texture, hardness, durability, and workability.

Unlike other stones, laser engravings done on granite are well suited for external applications of varying climatic conditions.

Some of the standard applications of laser engraved granite are:

  • Custom flooring
  • Novelty Gifts
  • Tombstone
  • Worktops
  • Picture engraving
  • Jewelry

Best Laser Machines for Engraving Granite

Trotec - SP Series Laser Machines

Work area size comparison of SP series of laser cutters
Work area size comparison of SP series of laser cutters

SP series of laser machines from Trotec are large-format CO2 laser cutting or engraving machines.

These are industrial-grade laser machines and are suitable for 24x7 production applications.

It has a large work area suitable for working on custom flooring applications that requires processing large granite sheets.

SP series is available in four versions, SP500, SP1500, SP2000, and SP3000.

SP3000SP2000SP1500SP500
Laser power60 - 400W60 - 400W100 - 400W60 - 200W
Footprint121" x 154"99" x 127"111" x 80"76" x 49"
Working area87" x 126"66" x 99"59" x 49"49" x 28"
Maximum workpiece thickness2"2"2"4"
Machine height45"48"51"45"
Maximum processing speed2,340 ipm2,340 ipm3,900 ipm6,000 ipm

A comparison of different variants in the SP series of laser machines

SP series of laser machines have laser power options ranging from 60W to 100W, and you have the flexibility of choosing the power you need.

Other than granite, it can also work on wood, glass, acrylic, plastic, leather, paper, and fabrics.

Trotec offers its control software named "JobControl" and "Trotec Ruby" to control the machine. It accepts standard design files exported from most CAD software.

They offer a two-year warranty for the laser machine and a three-month warranty for the laser optics.

Trotec provides excellent customer service, and you can contact them via phone, email, or visit their office for queries.

They offer prices through consultation by listening to your requirements and then customizing the machines for your specific applications.

OMTech K40

OMTech K40 desktop laser engraver
OMTech K40 desktop laser engraver

OMTech K40 is a desktop laser engraver that houses a 40W CO2 laser and provides a work area of 8" x 12". It has a 32" x 20" footprint and weighs around 51 lbs.

It is a good option for hobbyists and small businesses planning to do small-sized engraving jobs on granite.

Other than granite, it can also work on ceramic, fiberglass, anodized aluminum, acrylic, glass, Delrin, leather, plastic, cork, and more.

It can house workpieces of up to 2.5" thickness. The maximum engraving speed of K40 is 1,000 ipm, and the maximum engraving resolution is 1,500 dpi.

Almost all K40 laser cutters have an enclosed setup with a built-in exhaust fan and an E-stop switch to provide a safe working environment.

The CO2 laser tube used in K40 has a lifespan of 2,000 hours and is consumable.

It uses a red dot pointer to trace the laser path. This is because its laser beam has a wavelength of 10,600 nm, which is outside the visible spectrum.

Electromagnetic Spectrum
Electromagnetic Spectrum

K40 comes with LaserDRW software for controlling the machine. It works on computers running on Windows OS and supports formats like JPEG, JPG, TIF, BMP, WMF, EMF, and PLT.

OMTech provides a two-year warranty for the K40 laser machine and a 6-month warranty for the laser tube and power supply.

They offer good customer service, and you can reach them via phone or email.

OM Tech also provides a higher power version, OMTech 60W CO2 Laser, ideal for applications where faster processing speed is desirable.

OMTech K40 Laser Engraver
A 40W CO2 laser engraver/cutter with 8 x 12 inch Work Area.
Integrated cooling fan, red dot pointer, LCD display, water cooling, and more
K40 comes with a two-year warranty.

Additionally, for laser engraving granite, you can also use laser machines like ATOMSTACK X7, LU2-4-SF version of Ortur Laser Master 2, Glowforge Plus, and other alternative lasers similar to Glowforge.

Final Thoughts

With a good laser engraver and optimized design, you can produce high-quality engravings on granite.

Black fine-grained granites produce the best results for laser engraving, with no or minimal post-processing requirements.

Engravings performed on granite are wear-resistant and long-lasting, making them suitable for outdoor applications.

It must be noted that minerals like quarts and the polished surface of granites can reflect the laser beam which can be dangerous if comes in contact with the eyes.

Therefore, it is recommended to wear appropriate laser safety glasses and strictly follow the laser safety protocols when laser engraving granite.

Laser Cutting and Engraving Other Materials

Following are some detailed guides on laser cutting more materials.

MaterialLink to Guide
PaperLaser Cutting Paper
AcrylicLaser Cutting and Engraving Acrylic
AluminumLaser Cutting and Engraving Aluminum
LeatherLaser Cutting and Engraving Leather
PlasticLaser Cutting and Engraving Plastic
PolypropyleneLaser cutting polypropylene
BrassLaser Engraving Brass
FabricLaser Cutting Fabric
FeltLaser Cutting Felt
FoamLaser Cutting Foam
Wood (cutting)Laser Cutting Wood
Wood (engraving)Wood Laser Engraving
PlywoodLaser Cutting Plywood
Glass (cutting)Laser Cutting Glass
Glass (engraving)Laser Etching and Engraving Glass
GraniteLaser Engraving Granite
VinylLaser Cutting Vinyl

Laser Cutting Guides for other Materials

Frequently Asked Questions

What are the different types of stones a laser engraver can work on?

A laser engraver can work on stones like slate, basalt, pebbles, ceramic, sandstone, granite, limestone, marble, and similar stones. However, the stones which give good contrast when laser engraved are granite, marble, and slate.

Which laser machine can engrave granite?

Granite can be engraved using fiber, CO2, and even a diode laser. But for engraving with high quality and detail, a CO2 laser with powers ranging between 40W - 80W is the best option. Diode lasers are not that effective, and it takes more than five times the time taken by a CO2 laser to do the same job.

How long does laser engraving on granite last?

The engravings on granite can last for a long time, even until the granite completely weathers off. When kept in external climatic conditions, the engravings can fill up with dust, moss, etc., gradually covering the engravings. A single wash can easily recover such engravings if they are post-processed with sealant paints.

About John

Hey I'm John. I talk about CNCs and Power Tools at Mellowpine. I'm a CNC hobbyist who has been making CNCs and writing about CNCs for a while. I currently also work as a consultant for business owners and hobbyists setting up their own CNCs. If you have any questions related to CNC, I'd be happy to answer them. Reach me at john@mellowpine.com

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John

Hey I'm John. I talk about CNCs and Power Tools at Mellowpine. I'm a CNC hobbyist who has been making CNCs and writing about CNCs for a while. I currently also work as a consultant for business owners and hobbyists setting up their own CNCs. If you have any questions related to CNC, I'd be happy to answer them. Reach me at john@mellowpine.com

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