Different substrates present their own distinct challenges for laser engraving photos. A laser engraved photo on wood may be totally different than the identical image that is engraved into clear acrylic or black aluminum. Consider these tricks and techniques you can use to improve your results on wood, acrylic and coated materials:
- Simplify the image: For all types of product, simplify the image by removing all unnecessary parts, predominately the background image. Also, consider outlining the graphic to allow you to select the image and/or background when converting it into a negative/positive, giving it a nice contrast around the edges. Make sure your final image is in a grayscale or black-and-white format.
- Positive and negative images: It’s important to understand the basic difference between a positive and negative image. Think of a normal photo that you see in a magazine as a positive image and the exact opposite, a negative. Ask yourself, “What will happen when the laser burns? After I am done, will the laser-engraved graphics be white, silver, dark brown or some other color?” For acrylic, when the laser fires, the engraved image will end up being a whitish frosted image. For wooden plaques, when the laser burns, the engraved graphics will likely be a darker image. Usually, if the engraved graphics will be darker than the surrounding area, use a positive image. If the engraved area is lighter than the surrounding area, use a negative image.
- Acrylic: Because of its transparent nature, this clear piece can be placed in front of a white or dark-colored wall, and will have totally different looks. The way the light reflects off acrylic will also give you a different result. For acrylics, convert the photo over to a true black-and-white image to get better results than engraving halftones, which force you to deal with dithering, resolution and gamma. When engraving clear acrylic, use a negative image with the background removed.
- Wood: Test scrap pieces of unknown woods as power settings are important. Whenever you engrave photos, especially into wood, you do not want to engrave too deep. As a rule of thumb, the deeper you go, the less detail you can obtain, as the laser dot does not vaporize that exact small dot, which becomes slightly enlarged due to the burning process.
- Coated Materials: Because of the consistent finish, engraving onto a coated material tends to be the easiest. Common products include aluminum, anodized aluminum and various painted materials. Other than tweaking your laser power settings for different coatings, you pretty much need to just decide whether a positive or negative graphic is required.
—Richard Korbyl, Columbia Awards