Guide: Etching Glass with 10 Watt Laser with Dry Moly

[gil.a.ramirez]

Greetings,

I finally had a comission that required me to laser etch glass. I found that there is no definitive guide on how to accomlish this online, and nothing specific to the Snapmaker, so I am posting my process in hopes of making your lives a little easier. First off, this was a rush project. I had to etch four clear glass vases as quickly as humanly possible (I was notified about 48 hours before they needed to be used) so I did not document the process with pictures thoroughly. I am, however, living through the process in real-time and have successfully developed the workflow.

I am not in anyway advocating for use of this process, merely documenting it for sicentific purposes.
It is provided without warranty of any kind. Proceed at your own risk:

1. First and foremost you will need to obtain a can of CRC Dry Moly Lube (or equivalent). Why? Because Molybdenum is a non-stick substance used for lubricating things like locks but is also a key ingredient in products like Duramark, a well known laser etching compound. If you want the highest quality etching, Duramark is what you want. For us poor folks, let’s continue on. There’s other kinds of dry lubricant that you may come across. If they are not Molybdenum based DO NOT USE THEM.

2. Procure your glass object (plus 1-2 tests/spares) and a test surface. I used clear glass cylindrical vases for this commission, and one glass picture frame for $1.25 each from the nearest dollar store.

3. Wash your glass object. I cannot stress how much time was wasted because I didn’t know this. The glass we get from the store is oily. Why? Get this! It’s the initial stage of a process called “Glass Diease” or crizzling. Basically, alkali compounds form on the surface because the glass’ chemical composition is unstable (because I bought it for $1.25). This alkali compound totally hosed my first coatings of dry moly by making it do this:

It made the glass impossible to secure into the chuck. It made the glass slip and slide ruining my first run. AAGH! Just wash it! I had the same problems with the picture frame glass pane I used for the material test. Trust me, it’s worth doing. Oh, and dry it too, for you “instructions unclear” people out there.

4. Conduct your material test.

4.a Coat your test object. Place a light coat of dry moly on the surface following the directions on the can and being safe. I eventually found it was easiest to wear nitrile gloves during handling of object with dry moly to keep the mess contained. Having to hunt down and wipe down every surface I touched after my test run, well… it sucked. To get a nice coating I recommend to spray lightly (8-12 inches away) let it dry about a minute (you will see it dry from black to grey very quickly) and hit it again until you have no light coming through (for me it was an average of 3 coats).

4.b Mount the test object. I recommend a flat pane for that, but you do you. If you need a tutorial on how to mount your object, please close this post, and proceed to pack up your Snapmaker and return it. (Just kidding) Use your imagination and experience. Everyone does it their own way.

4.c Set up your material test, which typically looks like this (without the cracks, yes, quit critcizing me. I told you I’m in a hurry, besides, there’s a reason…)

I use Lightburn for processing my laser gcode and under Laser Tools > Material Test you can set up this exact material test by simply adjusting a few parameters. This is my setup whenever I have brand new material.

Now, I’m not advocating for Lightburn, but doing this by hand sucks. If doing things by hand is your thing, you do you. For the rest of you, get Lightburn. Typically I do at least two material tests, this one, and a more narrow one to really fine tune the performance. Not on this job, though. Moving on.

So the reason the test pane cracked (and my first production test vase) is that the power beyond 70% was too high. It heated and cooled the glass too fast. I’m not going to go into it right now.

Based on these tests I chose a fill profile setting power at 70% and speed at 1000 mm/min. Initially those settings proved to be too light. I then added crosshatch and reduced the line interval and it made the etching pop much better.

Later I upped the power to 75% when I noted that the vases are “geometrically challenged” and not actually circular. I had to overpower the cuts due to the laser losing focus when the surface went out of round. I sure do love me some dollar store vase.

7. Spray your object(s). Same process as spraying the test but don’t get crazy. Dry moly is a pain to get off your hands and stuff, and it’s LUBE. I tried to hug my wife and she slid right out at 30 mph. So spray a nice area round your design, but not the whole object lest you enjoy cleaning fingerprints off everything you touch. Again, you do you, BUT wash . It . First .
   

   

8. Set up your production run. I am using the rotary axis so be sure to turn on Rotary Setup in Lightburn if you’re using the rotary! (unlike me on my first run where I ruined the vase!) If you need help with setting up a run with the rotary, “look it up, dear”! If your cup/vase doesn’t fit, I have a customized rotary jaw extender STL I printed in TPU that I use for that. Feel free to check it out here.
   

   

9. Run the first test. If the Snapmaker gods have mercy on your project, it will go great. If not, you’ll have to do some creative Jury Rigging to make it work. The glass is so smooth my TPU jaw extenders still had a hard time and I was afraid to put the uncovered chucks on it because it could crack the glass. So I added Sticky Tack to get some real grip on it, and added some wood blocking because the base of the vase was thicc.

10. I ran several tests as I mentioned above on the same object. Intially ran at 100% @ 1000 mm thinking the thicker glass would hold up. It did not. I also adjusted to cross hatch and reduced the line interval so the lines were not so evident. It also helped to pick up the fine details which came in as a single line on the first run.
    

    
    
    
    

After beating my head against the wall a dozen or so times I got it right.

Hope it helps.

[Hauke]

Just one addition: If you use Lightburn anyhow, I can only recommend to use “Offset Fill” - IMHO the results are clearly better: Laser engraving glass - tried several methods, here are the results - #31 by Hauke

[nweolu]

Golden thread. Thank you!

[Slfeth]

I figured out essentially the same process but I used Luban. I read about Lightburn but since Luban was working I didn’t try. I couldn’t find where to buy dry moly (where did you get it?) so I used Ceramark. It’s pricey and be sure long term storage is upside down, but I think the mess might be less and cleanup is easy with water (although I wore gloves to keep fingerprints off the glass). I might have lucked into washing as my cheap glasses had a haze, but also from my scientific lab work fingerprints are bad. Some things to add, I cut pieces of those sticky silicone things for securing rugs and put them between my vice and the glass (still managed to break a few by tightening too much). I also found some paints at Johnson plastics that are designed for engraved items (metals and things). They wipe on (I use a gloved finger) and stick in the engraved part. You can wip off the extras and clean anything that doesn’t come off with isopropyl alcohol. Pretty easy once you figure out your technique. I’ll post a few pics after I find them.

[Slfeth]

Turns out finding the pictures was easier than uploading. Let me know if they got there.

[Slfeth]

[Slfeth]

[Slfeth]

[Slfeth]

[Slfeth]

I’ve also had good results etching the back of mirrors, no “blacking” required. Even worked with the lower power laser as did some of the etching but large areas tended to get too hot and have issues.

[gil.a.ramirez]

That’s some gorgeous work @Slfeth. Thanks for posting it.

[gil.a.ramirez]

Fantastic recommendation. I’ll have to try using offset fill on the next job.

[spitzlbergerj]

Hi,

I tried this with the same workflow quite a while ago and also had good success. However, the biggest annoyance was removing the dry moly.

Do you have any tips on this? How did you get it off again without ruining the glass?

Greetings
Sepp

[gil.a.ramirez]

I just scrubbed it off with a sponge. If you don’t apply too many coats it isn’t too difficult. Somewhere I read that acetone can make it easier, but I did not research it further. I would recommend doing your homework to prevent unknown chemical reactions. Stay safe!

[PeteNelson]

I’ve only tried engraving glass once, but it worked great for me on my A250 with the 10W laser. I had a piece of plain flat glass I bought for a different project. I coated the glass as smoothly as I could with some black fabric ink (like for screen printing t-shirts). I had no idea if it would even stick to the glass, but it did. I dried the ink with a hot air gun, then put it coated side down on the laser bed. (Remember to mirror what you want to engrave if you want the engraving on the “front” of the glass). I had to manually focus the laser, since the automatic thickness wouldn’t work. In Luban, I used vector engraving, method Fill, movement mode Line, Line Interval 0.1 mm, Line Direction horizontal, Jog Speed 3000 mm/min, Work Speed 400 mm/min, 100% power, Constant Power Mode set (checked), and no changes to optimization. The etching came out clear and looked good to me. The black ink just washed off with water and didn’t leave any residue. I will try again with black tempera paint, which I have heard people have had success with. I think you can use pretty much any black coating that comes off of glass easily and coats it relatively smoothly. I don’t think you need anything special. For me, etching clear acrylic without leaving bubbles or staining has been much more difficult than etching glass was.

[gil.a.ramirez]

I am continuing to calibrate and finally had some time to sit down and work on engraving an image on glass. I used the same dry moly process and imported an image straight into Lightburn. It created a greyscale image based on the original, and I played with the settings until I was happy with it. I used the standard dithering selection. My final settings are 50% max power, 1000 mm/min work speed, and 262 dpi.

Test 1: 20% power, 1000 mm/min, 163 dpi.

It came out a bit too light. With the backlight it looks great, but in natural light the image is hard to see, but it has the best shading, I think.

Test 2: 70% power, 1000 mm/min, 163 dpi.

It was too powerful and overexposed some parts.

Test 3: 50% power, 1000 mm/min, 262 dpi.

I was most happy with this one in natural light and backlit.

Hope it helps you out!

[sdj544]

@gil.a.ramirez

First and foremost you will need to obtain a can of CRC Dry Moly Lube (or equivalent). Why? Because Molybdenum is a non-stick substance used for lubricating things like locks but is also a key ingredient in products like Duramark, a well known laser etching compound. If you want the highest quality etching, Duramark is what you want. For us poor folks, let’s continue on. There’s other kinds of dry lubricant that you may come across. If they are not Molybdenum based DO NOT USE THEM.

Moly isn’t necessary for glass. It is for stainless. I’ve used dry graphite spray, airbrushed tempera paint, paint marker and sharpie, all with equal effectiveness on glass. I do prefer the moly because it gives the most even coat and it’s the least fragile for handling. Tempera paint is great because it just washes off with water, but the surface is very fragile. The others come off easy enough with alcohol.

The price of the CRC brand moly has gone up and it’s been hard to find lately (too many people using it for lasering?) I tried this brand I found on Amazon and it works equally well:
http://amazon.com/dp/B000AYHK9K

This is the graphite I’ve tested and I’ve been able to find locally:
http://amazon.com/dp/B0094IZ3BA

-S

[gil.a.ramirez]

I cannot agree nor disagree with your statement since I have not tested other coatings. In order to achieve good etching, perhaps you can share whether the same settings for dry moly work with other coatings and give us some images showing the differences?

[gil.a.ramirez]

I went to ahead and tried seven different coatings to see how’s they would absorb heat and etch the glass.

1. Black acrylic paint
2. White acrylic paint
3. Silver acrylic paint
4. Black patio tile paint
5. White enamel spray paint
6. Dry Moly
7. Black engine enamel spray paint
   Here they are.
   
   

None of the materials seemed to be vastly superior and others in absorbing laser energy, though the black were perhaps slightly more efficient at it. However, dry moly was definitely the easiest to clean.

I later read from Enduramark that lasering dry moly releases sulfuric acid, therefore nobody should use it! Thus I am going to suggest that other options like tempera or acrylic paints be your first option! Be careful!!