How to Engrave Black Granite
Processed Material Examples

How to Engrave Black Granite

The other day, we received a request to engrave an image on black granite. In the end, we were finally able to get a clean engraving, but in order to do so, we had to make some adjustments to the data...
In today’s entry, we look at how to create data to engrave on granite.

Checking the Color Gradient

When engraving the granite, the first thing we noticed was that, unlike wood, it is much harder to see the color gradient. So first, we tested it by engraving a few different shades of gray as shown below.

different shades of gray

Here is the result. Frankly, the difference is unnoticeable beyond 60%. Based on these results, it’s unlikely you’ll be able to get a clear engraving without making the black and white of the data much clearer.

different shades of gray - result

How to Prepare the Data

Now, we will create the actual data. All of the following will be done in Photoshop, however it is also possible to do so in free software such as Gimp, so feel free to try it yourself.

Cropping the Image

Here’s the image to be engraved.

image

First, we removed the background so that the focus is the subject only. We recommend cutting out the background as much as possible as the subject will become clearer. You can cut with an automatic selection tool.

cutting out the background

Increase the Contrast

Increase the contrast of the color. Adjust with the tone curve.

increase the contrast

Change the Photo to Black and White (Grayscale)

Color photos can be imported into our software, but it is difficult to make adjustments as they are, so it is best to change them to black and white.

change the photo to black and white

Increase the Contrast

Increase the contrast here as well. Adjust the middle color with the tone curve.

increase the contrast

Invert the Color

Normally, the material is blackened when engraved with a laser cutter, but granite turns lighter and therefore the black and white parts of the image are reversed. Combine the layers and click Menu→Image→Color Correction→Invert.

invert the color

Increase the Contrast

Here, you will increase the contrast a final time. Use the tone curve and ensure that the black and white are clearly separated.

increase the contrast

Correct the Specific Part You Want to be Clear

The shirt and arm sections are black and will likely be filled in completely, so individually select and adjust the color. Brighten it and make the black and white clear.

correct the specific part you want to be clear

Save

Adjustments done. Save the photo as a jpg. file.

Processing

We conducted the processing with the FABOOL Laser Mini 3.5W.
Speed: 800 Power: 100 Passes: 1 DPI: 254 Size: 110x110mm

Processing Results

processing results - 1 processing results - 2

This took 2 hours and 14 minutes.
Granite can be engraved without any issues if you take the time to prepare the data. This was done with FABOOL Laser Mini, but it is also possible with our other lasers, so feel free to try those as well.