How to Laser Engrave Glass without damaging it

Laser engraving on glass opens up endless possibilities for creating intricate designs, custom artwork, and personalized items. However, due to the delicate and brittle nature of glass, improper techniques can lead to cracks, chips, or unsightly damage. Whether you’re a seasoned professional or a beginner exploring glass engraving, knowing the right tools, methods, and precautions is crucial.

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Learn the best techniques for laser engraving glass without causing cracks or damage. This guide covers preparation tips, laser engraving curved glass, and tips and tricks for flawless glass engraving results.

How to laser engrave glass

When a laser beam hits a glass surface, the moisture and air trapped between the silica elements react by expanding. Since the glass is rigid, this expansion causes microscopic fractures on the glass surfaces which is what we see as fracturing and chipping or simply engravings.

The basic steps for laser engraving are quite easy to follow.

Step 1: Choose the Right Glass

Not all glass is created equal when it comes to laser engraving. Here’s what works best:

• Tempered Glass: Not recommended due to its tendency to shatter under heat.
• Soda-Lime Glass: Common in most glassware, suitable for laser engraving.
• Borosilicate Glass: Resistant to heat and ideal for engraving.
• Crystal Glass: Engravable but may require more precision due to its composition.

As mentioned before, the glass type used to laser engrave on makes all the difference. As a rule of thumb, avoid glass with higher lead content. You are better off with cheap glass found at most retail shops. Soda-ash glass is particularly great and common in most consumer products.

Leaded crystal glass or any other glass with heavy metal components poses a great challenge when engraving. This is because it makes the laser beam skip over some sections and hence leaves some spots unmarked. Additionally, these glass types may easily break under heat stress.

If you have to work with high-end glass types such as crystal glass, exercise extreme caution. Lead, especially, expands at a varied rate in comparison to the rest of the crystal. This can cause fracturing and breaking.

To know if your glass can handle the engraving, you may want to test it beforehand. In addition, adjust the speed and power settings on the machine, until you determine the perfect settings that will produce the look you desire.

Remember that the higher the number of times required to run the same design on the glass surface, the blurrier it will look. Therefore, you might want to know the right setting before starting your engraving project

Pro Tip: Test on a sample piece of your chosen glass type to avoid costly errors.

Step 2: Clean the Glass

A clean surface ensures smooth engraving and reduces the chances of unwanted marks.

Let the glass dry completely before engraving.

Use a lint-free cloth and glass cleaner to remove dirt, oil, or fingerprints.

Step 3: Mask the Surface

Applying a masking material helps protect the glass and ensures a more even engraving.

Smooth the tape to remove air bubbles.

Use transfer tape or masking tape to cover the glass surface.

This layer acts as a heat buffer and reduces chipping.

Step 4: Adjust Laser Settings

The key to engraving glass without damage is using the correct laser settings:

• Power: Low to medium (20-40%) to avoid cracking.
• Speed: Moderate to fast to minimize heat buildup.
• Frequency: Lower frequency settings reduce the risk of excessive heat exposure.
• Focus: Use slightly defocused laser settings for softer engraving impacts.

Pro Tip: Always perform a test run on scrap glass to fine-tune your settings.

Step 5: Use a Damp Paper Towel

Placing a damp paper towel or tissue over the engraving area can help diffuse heat and reduce chipping. The moisture absorbs excess heat and minimizes stress on the glass.

Ensure the towel is damp, not soaking, to avoid water interference with the laser.

Step 6: Secure the Glass

Ensure the glass is stable during engraving to prevent shifting:

• Use a jig or clamps to hold the glass in place.
• If engraving cylindrical objects like glasses or bottles, use a rotary attachment for consistent results.

Step 7: Engrave Your Design

Load your design into the laser software and align it on the glass. Double-check settings and alignment before starting.

Step 8: Post-Engraving Cleanup

After engraving, carefully remove the masking material. Clean the glass with a lint-free cloth and glass cleaner to remove residue or soot. If necessary use a nail brush to remove shards and rubbing alcohol to clean off any oil residue.

If you need some color on your engraving, add a pinch of Rub-n-Buff in your preferred color choice. Sometimes, the nature of the glass may blur the mark. In other instances, the image is too detailed to perceive with the naked eye. Follow the instructions on the tube to avoid creating a mess on your glass surfaces. 

Tips for Avoiding Damage

• Avoid overheating: Use lower power and higher speeds to reduce heat concentration.
• Do not engrave near edges: Engraving too close to the edge can cause cracks.
• Work in a ventilated area: Laser engraving produces fine particles that should be extracted.

Alternative Methods

If you’re concerned about damaging the glass, consider using laser-safe glass coatings or marking compounds like CerMark available on Amazon. These products create a temporary coating that allows the laser to mark the surface without direct engraving.

Laser engraving curved glass

For obvious reasons, it is easier to use a laser on a flat glass surface. With a flat glass surface, you only need to set the machine to a specific focal length (distance between the object and the lens). However, when the surface is curved, you will have to employ some tricks to allow some flexibility.

So, when engraving curved items like wine glasses, wine bottles, and steins, a rotary attachment will come in handy. But even then, you will likely run into some angle complexions and variations in curvature. In addition, the stein handles can bang against the lens as the cup rotates in the rotary attachment. This is where the depth of field comes in. 

The depth of field is the distance between the nearest point and the farthest point of sharp focus. When the laser goes outside this range, it loses focus and etches a blurry image. Anything within the depth of field will appear to be in focus and will ultimately create a clear and quality engraving.

After a few attempts of laser engraving on a curved glass surface, you will know how to set the right depth of field. To put it simply, you will need a couple of test runs before you become an expert in laser engraving on curved glass.

How to laser engrave curved glass

Begin by installing the rotary attachment in your laser machine to rotate the glass as it engraves on it.

Most of the roller engraving modules are pre-installed and very easy to set up. Normally the kit is plug and play and its most common uses are for the engraving of cylindrical objects like bottles, glasses, cans, pens and cups.

Most models also allow adjustment of the Z Height or the reposition of the base which accommodates the clearance required for for the rollers. If you are not sure about compatibility it would be best to look at wiring diagram specific to the the stepper motors.

Once done, set up your logo, image, or design on your software as if you intend to print on a physical paper. Send this to the laser and watch it beautifully transfer it to your glass objects. It is a quick, easy, and effective strategy of making your wine bottles, mugs, and wine bottles pop.

With glass laser engraving, the type of glass matters. Avoid expensive glass loaded with lead as it tends to retain heat and cause inconsistencies in the engraved product.

Check out our Best Laser Engravers for Glassware: Best Laser Engraver for Glassware

How to laser engrave glass with a Diode Laser using CerMark

Laser engraving glass can be challenging, especially with a diode laser, which lacks the power and wavelength efficiency of CO2 lasers for this purpose. However, by using CerMark—a laser marking spray—you can achieve clear, professional results with your diode laser. This guide explains the step-by-step process of using a diode laser and CerMark to engrave glass effectively.

What Is CerMark and Why Use It?

CerMark is a laser marking compound that bonds to surfaces under laser heat, creating a permanent, high-contrast mark. On glass, it acts as a medium for engraving, allowing diode lasers to produce visible and detailed results. It prevents issues like chipping, cracking, or insufficient marking that can occur when engraving glass directly.

Step 1: Gather Your Materials

Before starting, make sure you have the following:

• A diode laser engraver (e.g., xTool, Atomstack)
• Clean glass surface (e.g., a glass coaster or bottle)
• CerMark laser marking spray available on Amazon
• Lint-free cloth
• Masking tape (optional)
• Protective gear (safety glasses, gloves)
• Ventilated workspace

CerMark Ultra Laser Marking Aerosol, 2oz

Step 2: Prepare the Glass

1. Clean the Surface:
   Use a lint-free cloth and glass cleaner to remove dirt, dust, or grease from the glass. A clean surface ensures better adhesion of the CerMark spray.
2. Optional: Mask the Edges:
   If you want to protect areas of the glass from overspray or marking, use masking tape around the edges.

Step 3: Apply the CerMark Spray

1. Shake the CerMark spray can thoroughly.
2. Apply an even layer of the spray to the glass surface. Ensure complete coverage over the area you intend to engrave.
3. Let the spray dry completely. The surface should have a matte finish when ready.

Tip: If using CerMark paste, mix it with water to the recommended consistency and apply with a brush or airbrush.

Step 4: Set Up the Diode Laser

Secure the Glass:
Place the glass on the laser bed. Use clamps, a jig, or other stabilizing methods to keep it steady during engraving.

1. Focus the Laser:
   Adjust the laser focus to achieve a precise beam for engraving. Diode lasers typically require close focusing for effective marking.
2. Adjust Settings:
   • Power: High (85-100%) for most diode lasers.
   • Speed: Slow to medium for detailed engraving.
   • Passes: Multiple passes may be required for darker marks.
     Always test on scrap glass to refine these settings.

Step 5: Engrave the Design

1. Load your design into the laser software. Align it to the CerMark-coated area.
2. Double-check the settings and positioning.
3. Begin engraving.
4. After engraving, inspect the mark. If it’s too light, consider a second pass.

Step 6: Clean the Glass

1. After engraving, rinse the glass with water to remove the CerMark residue.
2. Use a soft cloth to wipe the glass clean, revealing the crisp, permanent mark beneath.

Tips for Best Results

• Work in a Ventilated Area: CerMark fumes can be harmful; ensure proper ventilation.
• Choose Simple Designs: Diode lasers have limitations in engraving speed and resolution; simpler designs often produce better results.
• Test on Scrap Glass: Each laser and glass type behaves differently; testing helps avoid mistakes.

Using a diode laser with CerMark is a cost-effective way to engrave glass with precision and clarity. While diode lasers aren’t typically designed for glass, the addition of CerMark expands their versatility, enabling high-quality markings on glass surfaces. With careful preparation and technique, you can create beautiful custom engravings without cracking or damaging the material.

Tips and tricks for laser engraving glass

• Use a damp paper towel

Too much heat is the number one reason for fracturing and breaking of glass during laser engraving. This is particularly common in glass objects with high lead content. To avoid this, place a moist paper towel over the engraving area before starting the project.

This helps dissipate heat better and ultimately protects the glass from breaking. The wet paper towel also leads to a white, clear engraving result. Ensure that the paper doesn’t have wrinkles or air bubbles as these may show on the end product.

If you don’t have a wet paper towel, use a damp sheet of newspaper instead. Some people also make use of dish soap to coat the surface prior to engraving. This works just as well. The only thing with moistening agents like dish soap is that they dry out eventually. For the best results, remember to reapply repeatedly.

• Utilize a lower DPI

A lower resolution or DPI (dots per inch) is bound to produce a better frosting effect because it engraves dots away from each other. When all is said and done, you won’t easily tell the image was printed with a lower resolution as the product will look fantastic in the end. This also prevents rough etched glass. The recommended DPI value for laser engraving on glass is 300DPI.

• The right grayscale

To get the best photo effect on a laser, use grayscale rasterization of 80% black. This reduces the heat applied to the glass and ultimately leads to a better result. This genius trick is guaranteed to create a smoother result as well since the engraving will not be black.

• Jarvis Dithering

Jarvis dithering is a method used to scramble the dots engraved on the glass. It is employed to shorten the time of engraving and effortlessly create a high-resolution image. When you use Jarvis dithering, you will have a smooth image and lower your chances of chipping and rough edges.

• Reduce the engraving speeds

If you are working with bottles and other curved surfaces, you will encounter both soft and hard spots. Without the proper engraving parameters, you may end up with light and heavy frosted surfaces in different areas of your item. To counter these discrepancies, engrave with high power and minimum speeds.

Laser engraving a mirror

Like clear glass, you can also engrave a mirror to create an outstanding and dramatic effect. The same procedure of laser engraving on glass stands for laser engraving on mirrors. The only difference is that with a mirror, engraving happens on its reverse side.

Basically, you will reverse the file or simply “mirror’ it to make it appear in the correct way when you look at the mirror. The thickness of the coating on the mirror largely determines the outcome of the engraving project. When in doubt, simply begin with a lower output, increasing it as you go until you arrive at the correct one.

For detailed information on how to laser engrave a mirror then read this article I wrote:
Can you laser engrave a mirror?

Advantages of laser engraving glass

There are a number of technologies used to etch glass including sandblasting, wet etching, glass reflow processes, and reactive ion etching. However, laser engraving is advantageous over these processes. Here’s why.

• Fast and precise: for the same amount of time you need to make a stencil for a sandblasting product, you can laser engrave a dozen of items. In addition, lasers give your engraving a high degree of detail thanks to its high precision. If you have intricate designs and pictures, you can employ laser engraving for the highest precision.
• Consistent: with laser engraving, your designs are saved as files and can later be reproduced to create the same quality. Furthermore, having no point of contact during the engraving process means there are less camping and breakage of the sheets.
• Cost: laser engraving on glass is a very cost-effective technique of marking glass. Unless you have the money to spend on high-quality sandblasting, laser engraving will do just fine. in fact, even though sandblasting is quite pricey, the end product of a laser engraved glass item doesn’t differ very much from one that is marked through sandblasting.
• Simplicity: unlike other glass marking technologies, laser engraving eliminates the need for masking. When you need to engrave an image on both sides of a glass surface, simply flip them over and start your laser. This is also true for glass with complex curvature.
• Easy to execute: compared to sandblasting and mechanical engraving, lasers are flexible and more forgiving. They also require minimal cleaning.

Frequently Asked Questions

Final Thoughts

Laser engraving glass can produce stunning results when done correctly. By choosing the right glass, preparing the surface, and using proper laser settings, you can avoid damage and achieve high-quality designs. With a little practice and attention to detail, you’ll master the art of glass engraving and unlock endless creative possibilities.