Laser engraving is a very practical and useful marking technology and it comes as no surprise that it is increasing in popularity by the day. As laser technology improves, laser machines are getting less expensive and more versatile at the same time. This creates a wonderful opportunity for almost anyone to set up a laser engraving business in their garage. In this article, we are going to go through some important tips and tricks that can make your laser engraving journey easier and more rewarding.
Laser engraving tips and techniques for acrylic
Acrylic is one of the commonly laser engraved materials. In fact, it comes second only to wood. Acrylic is not only inexpensive but also very easy to cut and this coupled with the fact that it comes in lots of shapes and sizes is what makes it such a hit for laser engravers.
Acrylic can either be cast or extended. Cast acrylic is ideal for almost any laser engraving project. When cast acrylic is laser engraved, it produces a frost that gives a beautiful white contrast. On the flip side, extruded acrylic remains clear when engraved with a laser beam. Knowing this difference is important because it will help you know which type of acrylic to go for depending on the results you are looking for.
For best results, engrave acrylic on the backside as this will give you a look-through effect from the front. Removing the back protective cover before engraving can also help you to get a sharper result. However, the top protective layer should be left on because it helps to safeguard against scratching of the surface due to handling. When engraving your acrylic from the backside, remember to mirror your image before sending it to the legend. Also, use low power and high speeds because high power levels can distort the acrylic.
If you are looking to achieve a deep engraving on acrylic, use a mylar mask or transfer tape. However, if you are looking to perform a light surface engraving, no mask will be needed. There are some acrylic materials that are painted on one side. When working with such, you can laser engrave right through the paint into the underlying acrylic and it will actually give an awesome contrast.
The engraving speed for a painted acrylic surface should remain the same as the speed you would use to engrave a clear surface. However, you can turn up the power by approximately 10% to achieve a cleaner cut through the paint. It is important to exercise caution when engraving through painted acrylic surfaces because using too much power will melt the paint thereby resulting in distortions. Once you have finished engraving, wipe away any smoke residue with an acrylic cleaner and a soft cloth.
CAUTION: Do not leave the legend system unattended when vector cutting acrylic because acrylic is very flammable.
Laser engraving tips and techniques for wood
Wood is arguably the most laser-friendly material on the market. You can use your laser engraver to either laser cut or laser engrave different types of wood depending on what you intend to achieve. The lighter-colored woods like cherry and maple are great for laser engraving because of the aesthetically appealing contrast they produce. So, if you are looking to create wood-engraved items for selling on Etsy or on your own website, go for the light-colored woods. Just make sure you have the engraver that is suited for wood. See my recommendation on the link below.
The denser the wood, the more laser power you will need to cut through. For instance, hardwoods will need more laser power than softwoods. It is therefore important to understand the characteristics of a certain type of wood before you embark on engraving it. If you visit your nearest woodworking shop, you should easily get lots of information on the type of wood you are interested in for your project.
Walnut, Maple, Oak, Cherry, and Alder are the most commonly laser engraved hardwoods because their grains work very well with laser engravers. Oaks have the largest grains and so the engraved work will not be as neat as Maple, Alder, Cherry, or Walnut all of which have relatively small grains. Read my detailed post on engraving wood on this link.
Plywood is typically used as a building material and it doesn’t respond very well to laser engraving. Because it is made from wood chips, the grains in the plywood run in all manner of directions and this makes it pretty hard to get attain depth consistency when laser engraving. Additionally, air bubbles in the plywood can interfere with the laser beam and this means achieving a neat laser cut is almost impossible. However, there are some specialty plywood products that can actually engrave surprisingly well. These specialty plywoods are typically found in hobby shops as opposed to the usual lumber supplier.
Contrast and depth
Contrast and depth are the most important factors when laser engraving wood. Increasing the power levels will increase the depth and contrast. Unlike other materials, wood discolors easily when laser engraved and this is the main reason why wood leads the pack of the best materials for laser engraving. However, wood needs a lot of laser power to engrave. Most wood will, therefore, need the laser power to be at 100% for best results. That said, wood is very easy to work with and you can create breathtaking designs with as little as 300 DPI but if you want a really phenomenal job, go for 600 DPI engraving.
Laser cutting wood tips
How effective the laser engraver will be to cut through your wood depends on how thick the wood is. The thickness of the wood will also dictate the wattage to use. For instance, cutting through ¼ inch of wood will require a 25-watt laser engraver while cutting through a ½ inch wood will need a 100-watt laser. Obviously, there are some techniques that can enhance the laser cutting of wood.
For instance, you can use a vector grid in order to raise the wood from the engraving table. This will help to reduce the backside burning of the wood. This space also helps to provide ventilation which makes it possible for the smoke and fumes to be removed behind the engraving cabinet. In some wood types, applying masking tape before laser cutting can help to reduce the buildup of residue on the surface of the wood.
CAUTION: do not leave your legends unattended when vector cutting wood because wood is flammable.
Cleaning the surface of residue
As you laser engrave wood, the resin will typically come to the surface of the wood and mix with smoke. This mixture is then deposited on the surface as residue. Woods that have some form of coating (e.g. polyurethane or lacquer) may not be affected much because the coating protects the surface from this residue.
But for wood that has no coating, you will have to remove the residue with a wet sponge or chamois. Mild chemical cleaning agents can also be used. In some cases, the residue might stain the surface but this can easily be taken care of by sanding the surface. Do not attempt to use a paper towel to clean the resin because the paper towel will shred and the shredded fibers will get stuck in the wood.
Wood color filling
You can color fill the engraved parts of the wood in order to create more contrast and make your engraved item more visually appealing. Color filling may not be needed for lighter colored woods like cherry and maple but some dark woods like walnut will look awesome with color filling. You need to be careful when color filling because the liquid color could easily absorb into the grain of the wood surface and show in unwanted areas. When filling your wood with black color, follow these steps;
- Apply a coat of Johnson’s paste wax on the wood surface. Check its latest Amazon prize here.
- Engrave your wood without wiping the paste wax and do not wipe away any residue or excess wax after you have engraved the wood
- Fill the engravings with a turtle wax “color magic” black liquid car polish. (Check Amazon list price here). The color will absorb into the engraved wood grains but it will not get to the surface because it is still covered in the wax
- Use a wet sponge with a mild cleaning agent to clean off the residue and wax from the surface of the wood
Tip: you can use the exact same procedure with other colors except that instead of care polish, you will need to use water-based acrylic paints. Do not use lacquer paints because they can easily bleed to the area surrounding the engraving.
Laser engraving tips and techniques for brass
It may not be possible to laser engrave uncoated brass but painted or coated brass is an exception to the rule. The laser beam will remove the coating thereby exposing the underlying brass. Brass-coated steel is the most commonly laser engraved coated brass.
The laser engraving process (when working with brass that is coated in steel) removes the paint thereby exposing the brass that is protected by the lacquer. The lacquer stops the brass from oxidizing and this helps ensure the bright surface remains so for years. If you aren’t sure whether your brass is coated in steel or not, just use a magnet to test it. Brass is non-magnetic but if it is coated in steel, the magnet will stick to it because of the steel.
For best results, set your laser engraver to high speed and lo power when engraving painted brass. This is because removing the paint needs very little power. If you use too much power, the paint will melt and this could distort your image.
If you notice a fat appearance when engraving brass, it is an indication you are using too much power. Just tone it down and you will get nice sharp images. Setting the brass palate on the engraving table and then raising the engraving table at about 0.20” can help increase the spot size and this will give you a smoother look and feel.
Brass pens are some of the commonly laser engraved items but before you get excited about laser engraving brass pens, make sure the pens do not have hard epoxy paint. Hard epoxy paint will not work very well with CO2 laser engraving because the engraving will result in a brown looking tarnished finish. To avoid this, make sure to only buy brass pens that are specially made for laser engraving.
Hack for laser engraving bare brass
If you must laser engrave bare brass, there is a little hack that can help – just go ahead with your laser engraving as usual even though it will not show on the brass plate. Once you have done your engraving, apply an oxidizing agent and this will produce a black image of the engraved vector. Make sure the brass you are using does not have a lacquer coating for this to work. It is not easy to determine if the brass has the lacquer coating or not so you may just have to experiment with it and see.
Laser engraving tips and techniques for glass
For the most part, the flat glass will have consistent toughness and this is why engraved areas will not have lighter and darker shades. On the other hand, curved glass like bottles and glasses will have soft spots which will cause frosting in some areas of the surface when engraved. To curb this, use a medium speed with high power when engraving.
Laser engraving can also be done on full wine bottles. As long as it is done correctly, the laser engraving shouldn’t have an effect on the contents of the bottle. Since you will only be engraving a small portion of the surface, there is very little likelihood of the bottle breaking. Follow the steps below to produce a smooth and frosted finish when engraving glass items;
- Use a paper towel to apply a thin layer of dishwashing soap over the surface of the glass
- Soak a piece of paper towel or newspaper in water and then wring it to remove any excess water and then place the paper towel on the glass surface and even it out to remove any wrinkles.
- Place your glass on the engraving table and laser through the paper towel before it dries out.
- Remove your glass from the table, discard the remaining paper towel and clean the glass surface. You might need to use a scotchBrite pad to polish the glass.
Exercise caution when laser engraving leaded crystal because the crystal will expand at different rates which can result in cracking and breakage of the crystal. To avoid this, use a lower power setting. But just to be on the safe side, have a spare in case the crystal breaks.
It is also possible to combine laser engraving with sandblasting to achieve phenomenal results. In such a case, use your laser to engrave your artwork on the glass and then use sandblasting for a deep etch in the glass. The process is quite straightforward – just apply a mask material on the glass surface and laser through it into the glass. Once done, remove the glass from the engraver and sandblast to the depth required and you will have your sandblasted/laser engraved item ready for sale.
Laser engraving tips and techniques for plastic
For best results, do not start engraving the plastic before removing the clear protective cover. You can then toy around with the speed and power settings until you have the best results. Taking the focus lens in and out of focus might also help in refining the quality of the products.
The idea is to enlarge the focus beam and thereby provide more beam overlap on either side of the laser. When you have a bigger overlap, you will also have a smoother engraved surface. For some plastics, using two passes is better. The purpose of the first pass is to cut through the cap layer while the second pass will clean away any residue that was left behind by the first pass.
Using masking tape to mask the plastic before engraving it can also help in preventing the buildup of residue. Once you have finished engraving the plastic, you can clean the surface with an acrylic cleaning solution like the Fritz Aquatics cleaner (here is the amazon link). The cleaner will remove any smoke residue and give it a nice polished and professional look
If you want to use your laser machine to laser cut plastic, make sure to use a vector grid in order to elevate your plastic before you commence the laser cutting. Just like is the case when laser cutting other materials, it is a good idea to experiment first in order to figure out the best settings to use for your project. Generally speaking, plastics that have a thickness of 1/16 inches can be easily cut with one pass. However, the thicker plastics might require two passes.
CAUTION: do not engrave PVC (Polyvinyl Chloride) because PVC can easily destroy the mechanics and optics of your legend. In fact, some laser manufacturers like epilog warn that attempting to laser engrave or laser cut PVC will void the warranty of the laser machine.
Laser engraving tips and techniques for aluminum
Anodized aluminum has a finishing coat that makes it more resistant to corrosion than ordinary aluminum. It is also the best aluminum for laser engraving projects. The laser machine can be used to remove the coating thereby exposing the bare aluminum which creates a nice contrast. there are lots of colors to choose from depending on your tastes and preferences but black anodized aluminum is the most popular because it produces the best contrast when laser engraved. Colors like red might not turn completely white when laser engraved and even upon a second pass, a slight shadow of the first pass might remain which compromises the quality of the image.
An important tip for engraving anodized aluminum is to use low power but with high speeds. This will give a clean and crisp image. If you use too much power, the anodize will overburn and distort the image. The laser engraving process removes the color coating on the aluminum and this creates room for the aluminum to accept new color. You can, therefore, brush aniline dyes or even use a felt tip marker to fill the engraved area with some color.
Laser engraving tips and techniques for marble
Laser engraving marble bleaches the surface color of the marble to reveal the underlying white-colored stone. When laser engraving marble, place the marble on the engraving table and then focus your laser engraver on top of the marble.
For best results, use a 2” lens for laser engraving marble. Before dislodging the marble, examine the image to see if it white enough and if not, run it again. Avoid using too much power though because it will create a washed-out effect. The laser engraving can go 0.05” into the marble and if you want to spice things up, you can fill the grooves with gold inks. Once you are done, wipe off any debris with a soft cloth.