Intro
The natural beauty of stone is remarkable enough on its own, but with engravings, stone can become a memorial to a hero or a personal accent to a home. Stone comes in all shapes and sizes, from river rocks to quarried quartz, and engraves surprisingly well with a laser cutter.
Stone Properties
Origins: Stone is a natural, non-organic material composed of minerals. It can vary in texture and hardness. There are three common categories of rock: igneous, sedimentary and metamorphic.
Igneous Rock: Created by cooling and solidification of magma or lava. Tends to be high on the hardness scale.
Sedimentary Rock: Formed by mineral deposits in bodies of water and solidified
Metamorphic Rock: Change from its original formation through extreme heat and pressure.
Homogeneous: Stone is made entirely of one type of stone, such as a single type of granite. Best for laser use.
Heterogeneous: Stone consists of multiple types of stone included as layers, veins or inclusions.of multiple types of stone or minerals. This type of stone is more complex to mark and engrave with a laser.
Stone Types Good For Lasers
Granite: Dark granite shows great contrast with photo engraving. Extreme hardness makes it great for outdoor displays. Polished surfaces are available, however, granite is coarse and crystalline, which works well for engraving detail.
Sandstone: Comes in many colors such as tan, brown, yellow, red, grey, pink, white, and black, and can often be found flat. Contrast well. Less dense than granite but can be brittle causing flaking.
Marble: Marble plaques show great detail with photo engraving. Very popular for its regal appearance. Low on hardness scale and tends to chip or break, if impacted. Tends to have heavy veins. Commonly used for interior decorations and countertops.
Basalt: Natural dark color creates excellent contrast with negative image photo engraving.
Slate: Low on the hardness scale and often with an uneven surface, slate comes in different uniformed shades and colors, often as pre-cut tiles. Engraves with great contrast.
River Rocks: River rocks and beach rocks are smoothed by the constant flow and pressure of water, which makes them ideal for engraving. They tend to mark as white, which is remarkably detailed.
Stone not recommended for laser cutting
Irregular Rocks: Rocks with multiple mineral clusters (heterogeneous) tend to be irregular in composition which can crack or chip the engraving.
Excessive Veining: Some stone, such as marble, has natural veins of minerals that can hamper a laser and create inconsistency in the engraving.
Precious Stones: Most gemstones simply aren’t affected by a laser. Material such as jade might work, but is expensive. We have no data on laser marking jade or other similar material.
Stone Applications
Gravestones & Memorials: Very popular application for personalized engravings to honored family members, heroes and beloved pets. Typically applied to granite, marble or sandstone (flagstone).
Art: Engrave dark stone is perfect for spectacular details in photo engraving. Marble and dark granite deplays great contrast and looks incredible on a wall in a living room or office.
Custom Flooring: Engrave logos, quotes or other branding concepts that you want to display prominently on floor tiling or marble surfaces. Works best with tiled flooring to create patterns or draw the eyes to a message.
Desk Accessories: Engraved marble name plaques and river rock paperweights marked with company logos are just two possibilities.
Signage: Stone signage weathers extremely well and gives a rustic feel
Outdoor Decor: Engraved rocks are great for decorating outdoor gardens and patios.
Personalized Hearthstones & Cornerstones: Add personal touches to fireplaces or commemorate the family home.
Novelty Gifts: Engraved river rocks make wonderful gifts for souvenir shops.
Honoring Fundraisers: Engrave brick plaques are popular ways to entice and thanks sponsors and promote fellowship.
Stone Considerations
Hardness: Stone is too hard for cutting with a laser and deep engravings have mixed results.
Surface Variance: Smooth or polished stone works best for engraving. Stone that is rough has less detail and can disrupt the image.
Shape: Stone can be found in all sorts of shapes and sizes. A flat, even surface works best.
Contrast: Like glass, the laser creates microfractures on the surface of the stone, creating a white engraving. This contrasts very good contrast on dark stone such as black marble.
Veins and Grain: Many stones have “veins”, or heavy graining, which create irregularities in engraving and marking. Choose stone with a low concentration of veins or position your marking away from veins.
Approach
General Approach
Much like engraving glass, the laser does not actually incinerate the stone, but rather leaves small microfractures on the surface, which create contrast and detail in marking and engraving. Shallow engravings work best and create the most contrast and detail on stone. Deep engravings have poor results on most stone and can be difficult to achieve
Cutting Stone
Stone is too dense for cutting. You will only waste precious laser power trying.
Engraving Stone
Follow basic rastering technique. Convert a high quality photo to a grayscale bitmap format and set resolution. Adjust power and speed to the density of the stone for a clean surface raster. For dark stone, you will want to “negative image” your photo in software.
Stone Finishing Tips
Stone doesn’t need much in terms of preserving, but you can add color to your engravings. The porous nature of most stone makes lacquer based paint absorb the color well. Avoid using acrylic based paints as these are not absorbed by stone and tend to make a mess.
Laser Settings
Your power, speed and other laser settings are going to vary depending on what kind of stone your are marking. Even the wattage of your laser and the local environment can affect settings. Because of this, instead of giving arbitrary settings, we recommend doing a materials test. You can download our Material Test and log book at our Laser 101 website.
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