What do you know about laser glass marking?

Glass marking can look simple, but one wrong setting can ruin a whole batch of products.

Laser glass marking works by focusing a UV or green laser beam on the glass surface, creating permanent marks without touching the material.

Many manufacturers think any laser can mark glass. This is not true. At Kirin Laser, we help clients choose between UV and green laser machines based on their exact needs. This guide shares what I have learned from years of working with glass marking.

How does laser engraving glass work?

If you do not understand how laser glass marking works, you may cause cracks, cloudy marks, or even break the glass.

Laser engraving glass uses focused light energy to change the glass surface or interior. UV lasers work in cold ablation mode, while green lasers use more heat for deeper marks.

Two Main Processes

Glass marking depends on how the laser interacts with the material.

Laser Type	Process Type	Heat Effect	Ideal Use
UV Laser (≈355 nm)1	Cold Ablation	Very low	Surface logos, fine details, delicate glass
Green Laser (≈532 nm)2	Thermal Effect	Moderate	3D inner engraving, decorative pieces

UV lasers remove material without heating it much. This reduces micro-cracks and keeps edges smooth.
Green lasers go slightly deeper, but they create more heat. This can cause stress and tiny fractures if not handled carefully.

Real-World Experience

One glassware brand I worked with wanted logos on thin wine glasses. They used a green laser first, but the stems cracked during washing. When we switched to a UV laser, used lower power, and optimized scanning speed, the cracking almost disappeared. Their logos became sharp and clear, with zero breakage.

What type of laser is best for engraving glass?

Using the wrong laser can waste money and damage your products.

UV lasers are best for fine surface marking and fragile glass. Green lasers work well for deep 3D engraving in thicker glass pieces.

Comparing UV and Green Lasers

Here is how I compare UV and green lasers when helping clients.

Feature	UV Laser3	Green Laser4
Wavelength	355 nm	532 nm
Heat Impact	Very low	Moderate
Marking Depth	Surface only	Deeper penetration
Best For	Precision, sensors, thin glass	3D art, thicker glass blocks
Risk	Minimal cracks	Stress fractures if speed is wrong

When to Choose UV

If you need perfect precision and want to avoid cracks, UV is the safer choice. This is especially true for:

• Medical or optical glass parts
• Consumer glassware like cups and bottles
• Electronics and sensors

When to Choose Green

Green lasers are good for artistic work where you want a 3D effect inside the glass. Examples include:

• Souvenirs
• Decorative pieces
• Thick glass blocks

I always warn clients to test settings carefully with green lasers to avoid stress damage.

How do lasers go through glass?

Many people wonder how a laser can mark inside clear glass without cutting it open.

Different wavelengths interact with glass differently. Green lasers pass through and focus inside, while UV lasers mostly work on the surface.

Light and Transparency

Glass is transparent to some light wavelengths and opaque to others.

Wavelength	Behavior in Glass	Result
UV (355 nm)	Mostly absorbed at surface	Sharp surface marks
Green (532 nm)	Passes through, focuses inside	Internal 3D engraving

UV light is absorbed quickly, which makes it ideal for surface etching.
Green light penetrates deeper, which lets us create designs inside the glass.

Practical Example

When marking a logo inside a souvenir block, I use a green laser⁵ with careful power control. This allows me to create floating designs inside the block without touching the outer surface.
For surface logos, like on wine glasses, I use a UV laser⁶ to avoid cracks and keep edges clean.

Challenges

Using too much power with a green laser can create bubbles or internal stress. This can weaken the glass or cause it to break later. Precision and speed settings are key to avoiding these problems.

What speed is needed for laser engraving glass?

The wrong speed can cause poor quality or even destroy the glass.

Slower speeds with lower power give cleaner marks. UV lasers need less heat, so they run at higher speeds than green lasers.

Speed Guidelines

Every material and laser setup⁷ is different, but here are general rules I follow.

Laser Type	Recommended Speed	Notes
UV Laser	Fast to moderate	Low heat, crisp detail
Green Laser	Slow to moderate	Prevents cracks, controls depth

Balancing Power and Speed

Speed and power must work together.

• Too fast: The mark is light and may fade over time.
• Too slow: The glass overheats and cracks.

I start with test runs on sample pieces. I adjust speed and power until I see consistent results.

Example From My Work

When I switched a client from green to UV marking⁸, we increased the speed slightly while lowering power. This gave perfect logos without thermal stress. Their production rate also increased by 20% because the UV machine worked faster and required less cooling time.

Conclusion

Laser glass marking⁹ depends on choosing the right technology and settings.

• Use UV lasers for precision, delicate glass, and clean surface marks.
• Use green lasers for deep 3D effects and artistic pieces.
• Always balance speed and power to avoid cracks and stress.

At Kirin Laser, we guide clients through every step, from machine selection to process optimization, ensuring their glass marking is consistent, safe, and beautiful.