How to Laser Engrave Glass without damaging it

Engraving on crystal and glass is commonplace in the world of customization. From printing a company logo on beer mugs to engraving the picture of bride and groom on wedding champagne flutes, laser engraving on glass creates elegance and sophistication. CO2 lasers are often used to produce quick and convenient results compared to traditional methods such as mechanical engraving and sandblasting. Due to its fragile nature, glass is a delicate material to engrave. However, if you know your craft well, you can open a new world of possibilities for your glass customization needs.

Laser engraving on glass is a fairly straightforward process. Begin by installing the rotary attachment in your laser machine to rotate the glass as it engraves on it. 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.

Advantages of laser engraving on 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.

How to laser engrave on 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 chirping or simply engravings.

The basic steps for laser engraving are quite easy to follow. Once you have correctly set up your laser and put the necessary safety parameters in place (refer to the user manual of your engraver), follow the following process:

  • Develop your idea (this can be an image, name, logo, design, etc)
  • Design it with the help of design software. While you are at it, be sure the engraver is compatible with your files. Some of the machines on the market are sold with their own software while others are created to be compatible with other software so find out the compatibility of your device with the software before you begin.
  • Send your design to the machine.  Depending on your device and software, you can adjust certain variables such as laser strength, number of passes, depth of cut, line thickness, and speed. This is why it is important to test the glass under varied settings to know the right combination for the best results.
  • After the engraving task is complete, clean your glass a little. 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-Budd 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. 

Laser engraving on 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.

Tips and tricks for laser engraving on 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.

Best glass types for laser engraving

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

There’s no denying that engraved glass items look unique and elegant. The process is just as simple and efficient. Compared to other glass marking technologies such as sandblasting and mechanical engraving, laser engraving on glass is also easy on the wallet, requires minimal cleaning and creates consistent designs.