How to Laser Etch Glass

Etched glass and crystal looks fantastic. Whether it’s engraving the bride and groom’s names on champagne flutes at a wedding or etching a company’s logo on beer mugs, engraving conveys a sophisticated beauty no matter the situation. Best of all, learning how to laser etch glass is easy.

Engravers like laser etching because a CO2 laser is faster and easier to use than other methods. You don’t have to spend time learning how to acid etch or sandblast. You don’t need to mess with glass etching stencils. All you have to be able to do is handle the glass. Of course, some glasses are better to work with than others. It’s much easier to etch window glass than it is to etch crystal.

Either way, though glass is indeed delicate, you can definitely etch it, no matter the type. All it takes is a bit of practice and some tips.

Types of Glass

Generally, regular glass is much easier to laser etch than crystal. Why? Crystal has a very high lead content. While this makes it refract light beautifully, it also means crystal contains a higher amount of lead. Lead is a metal, and CO2 lasers are not very good at working with metals. Worst of all, this lead retains heat.

Since lasers ablate material by vaporizing it, and etch glass by vaporizing the water and air molecules trapped inside the silica crystals, heat retention is a problem. The more the glass retains heat, the more the area around the etching spot gets heated. Eventually, the local temperature goes very high. It gets so high that each new pulse of lase energy makes a bigger pit than it normally would, and affects parts of the glass that it shouldn’t. This is because the areas are so close to vaporization temperature that the heat diffusing from the laser spot is enough to crack or vaporize them. As these areas around the spot fracture, the markings expand. Since the markings expand unevenly, this in turn produces distortion in the engraving.

One way to etch crystal more reliably is to use short focal length optics. Instead of a 2 inch optic, use a 1.5 or shorter one. These optics produce a higher power density spot, such that it takes vastly less time for the laser to vaporize the spot of glass. Less time spent on a particular spot means less heat absorbed by the glass. Less heat absorbed means more reliable results, and a sharper etching edge in all types of glass.

Using special high power density optics, you can even engrave very deeply in glass, rather than getting just the normal etch. You can laser engrave deeply enough to mount an inlay, if you want, though you’ll have to make multiple passes. Keep in mind that this is an advanced technique that will take some practice, and also has its limits. These are best found through trial and error with the materials you have at hand.

Make Sure the Glass Stays Cool

Heating issues don’t just affect leaded glass. Leaded glass just makes it more of a problem. Overheating is the main cause of breaks and fractures when etching glass. Therefore, you want to keep the glass at a suitable temperature. Many people find they get good results by draping a wet piece of paper over the surface to be etched, and etching through the paper. This reduces cracking and cratering in the final design. However, it also produces a frosted effect. Many people like this frosted effect, of course.

You can also put a thin layer of dish detergent over the glass area to be etched. This coating will help cool the glass during the etching process, preventing a heat buildup that leads to fracturing and chipping. Like wet paper, dish detergent will dry out over time. Make sure not to let this happen. A quick spray from a spray bottle will re-wet the object. Just don’t touch the object in the process of re-wetting it. Touching or bumping the object risks knocking it out of alignment, which would completely ruin the rest of the engraving by offsetting it from the previous parts.

Masking tape is another technique you can use for keeping the glass cool, and it won’t dry. Just put a strip of tape on the area to be etched. The tape will help avoid heating, and like the paper, it will also produce the frosted effect.

Etch One Pass Only

One thing to keep in mind when etching glass: the more passes you make, the blurrier the design gets. Therefore, you want to have your settings right the first time around. Ideally, use a test piece to dial in precisely the right settings. That way, you know you’ll get the right look. Then, run the final pieces in one go.

Etching Mirrors

Laser etched mirrors are a unique and very dramatic effect. The process is very simple. You have to etch the backside of the mirror, not the front side. Therefore, you need to use the engraver software to reverse or “mirror” the design, so that it looks right when you look into the mirror.

Now,you want to make sure the laser power is matched to the mirror coating. You don’t want to etch too much, as it could distort the edges of the remaining mirroring. Start with a low output power and dial it up as necessary.

Etching Rounded Glass Objects

While it is possible to etch rounded glass objects that are mounted in place, particularly if they have a large radius of curvature, this is not recommended. It’s much better to use a rotary attachment. This tool is capable of rotating the object under the laser head. It will produce much sharper and more reliable results.

One thing to be careful with when using rotary attachments: handles! Specifically, if the object is a mug or a beer stein, the handle may cause problems as the rotary attachment spins the object being etched. You do not want a beer mug handle knocking into your very expensive laser optics at high speed. Therefore, it’s suggested that you do a test run before engraving objects with handles. Make sure you know how to position the object at the beginning of an engraving run such that the handle never poses a danger.

Marking Compounds

You can add color to your etchings by using a compound known as ‘CerMark.’ This is a family of thermally bonded pigments that get bonded to the glass as it is etched. These pigments are best applied by spraying, because you need a very thin, very even layer of solution on top of the material that is being etched.

Start by cleaning the surface thoroughly, then spray a thin and even layer, just enough to cover the base color. Then engrave at full power with a speed below your laser’s maximum. The laser will both etch the glass and bond the pigment in one step. After the etching is done, clean off the surface. A damp cloth or water will remove chips, while buffing with a sco.

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