Introduction: How to Engrave Glass (Diode Laser Engraver)

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About: Thanks for stopping by! I'm Nir, a physics PhD student studying E. coli bacteria. On my free time I enjoy making all kinds of things - from laser cutting & 3D printing to baking, cooking and doing science expe…

In this instructable I'll show you an easy method for engraving glass on a diode laser. There are instructions online but the ones I found were overly complicated and required special equipment like a powerful air compressor and an air brush. These methods work great, but they require an additional investment and they're not always necessary. I'll also show you how I edit images for glass engraving, which is different from other types of laser engraving.

If you have any questions or comments, feel free to leave them at the bottom :)



If you prefer the narrated video version, watch the video I made :)


Why can't we just point a laser at glass and engrave it??

Every material absorbs different colors of light. For example, ordinary glass absorbs some UV light, but it does not absorb much light in the visible spectrum, which makes it transparent to our eyes. In order to cut or engrave a certain material with a laser cutter, the material must have significant light absorption around the laser's wavelength.

Many diode lasers emit light at a wavelength of 450-460nm, which seems blue to most people. Since glass does not absorb much light at these wavelengths, diode lasers are useless when it comes to cutting or engraving glass. So, in order to engrave glass we need to cover it with something that does absorb the laser beam.

Supplies

You'll need:

  • Something made of glass to engrave. These are the picture frames I used (laminated MDF).
  • Gouache/Tempera water washable paint.
  • A container larger than the glass you want to engrave.

*Some of the links in this article are affiliate links - buying through these links supports my future projects at no extra cost to you :)

Step 1: Mix Paint & Water

  • Mix paint with about 10-20% water. The mixture should be pretty thin so it can easily form an even coating, but not too thin that you need many layers of coating.
  • Pour the mixture into a large container, and blow away any bubbles left on the surface.

Step 2: Apply Two Layers of Paint

  • Dip the the glass into the diluted paint, and let the excess paint drip back into the container. I use a suction cup, but you can just dip you fingers and wash off the paint (or use gloves)
  • Put the painted glass on a drying rack. I made mine out of packing foam and some sticks.
  • Once the glue is fully dried, dip the glass once more and let it dry again.

Dipping twice is crucial - one layer won't be enough! It's still pretty translucent and you can't engrave it this way - you'll get really bad results. After the second layer is done, the glass should be painted evenly and be completely opaque - compare the 3rd image (one layer of paint) with the 4th image (two layers of paint).

Step 3: Prepare Your Design

Engraved glass doesn't have shades, so to get good results you need to turn them into black & white images, and keep the details to a minimum.I used Canva (pro) to remove the background of images (highly recommended!).

  • Import the images into Lightburn (I'm kind of assuming everyone is using Lightburn!).
  • Right click your image, and press 'Adjust image'.
  • Select 'threshold' as the 'Image mode', which is most suitable for black & white images.
  • Play around with the contrast, brightness & gamma until you're happy with the results of the adjusted image.

Step 4: Engrave!

  • Align the laser and set the focus to the surface of your glass.
  • Adjust the engraving parameters. I use 100% power @ 40 mm/sec.
  • Set the line-interval to match the thickness of your laser beam. My laser beam is 0.08mm x 0.08mm, and so I set it to that value.
  • Use the frame command in Lightburn you make sure your design is aligned with the glass.
  • I use a cheap wide-angle camera to align my laser engravings easily. It's not that good, but at 17$ it definitely gets the job done :)
  • Engrave!

Step 5: Wash the Excess Paint (OR NOT!)

Once the engraving is done, you can wash off the paint with some water and a soft sponge or a piece of fabric. However, you can also keep the paint on for a one-of-a-kind look. I like the negative-image so much more. If you like the extra contrast of the painted glass but you don't like the negative image, you can use Lightburn to invert the image before engraving, so the background is light and the figures are dark.

Step 6: Results!

I love the end results - the engraving turns out classy and clean, which is nothing like any other method I know of. I shared some free files just in class you like my designs, and an 'I Made It!' design for those who want to share their results in the dedicated section!

I hope you enjoyed reading and found some of my work useful :)

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