It's easy for artists to fall into the trap of assuming that high resolution always produces the best results. But with laser engraving this isn't always the case.
With laser engraving we work with image resolution in two places: the original image and the laser cutter setting. While in most cases starting with a high resolution image (300 dpi minimum) is best, increasing the resolution of the laser cutter doesn't always produce the best results.
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In this newsletter…
First, I share with how lowering the resolution of the laser cutter can improve engraving results. If you've been struggling with engraving photographs, read on!
Second, in this month's FreeFall Artists in the World feature, we look at Victoria Burge's new edition of prints (right) for Planthouse, a contemporary gallery and project space in New York City. Victoria used a laser cut Mylar stencil to create a varied edition of paper pulp prints, in collaboration with Dieu Donné.
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Finally, if you are looking to get a jump on holiday shopping, this year's ornaments—made from dyed wood veneer and pieced together by hand—are available on my website for a limited time. Click here.
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Laser Engraving and Resolution
Achieving a full value range with laser engraving is challenging. Photographs are prone to engraving dark with high contrast. In addition to formatting the file in Photoshop, lowering how many lines per inch (LPI) the laser engraves can help significantly.
Options for engraving raster images (JPEG, TIFF) vary depending on the brand of laser cutter. I work on a Universal laser cutter where LPI is called image density (ID). The standard image density is 5 (or 90 LPI). While I use this setting for 90% of applications, there are times when lowering the image density to 3 (or 45 LPI) gives better results.
Let's take a closer look.
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Part 1: Material Density
How well an image engraves at a particular resolution is directly related to the material's density.
Since the laser cutter is a heat-based medium, it engraves away more when the material is soft. When the number of lines per inch is high and the material is soft, a line can engrave wider than the diameter of the laser beam and bleed into the next line.
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If your images are engraving dark, with low contrast, this might be why.
Can't you fix this by lowering the power setting? While lowering the power setting may improve clarity of the dark values, it will also lighten the light areas, causing them to drop out.
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Part 2: Image Density
Let's look at an image engraved into cherry wood, using the same settings at two different image densities (below).
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The image on the left was engraved at 90 LPI. The result is a high contrast image, containing a limited number of values. The image on the right was engraved at 45 LPI. The subtlety and number of values here is much greater, bringing out more detail and a more pronounced sense of depth.
It's a bit counter-intuitive but with laser engraving, lowering resolution (LPI) can give you better detail than increasing resolution.
Try it for yourself!
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Note
The above image was first formatted in Photoshop. I played with lightening the darkest values, darkening the lights, and increasing the sharpness.
On my machine, when the ID is 3 (45 LPI) the laser can't cut vector lines. To cut out the block, I had to send the vector cut in a separate job with the ID set to 5. Check to see if lower resolutions affect cutting on your machine.
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FreeFall Artists in the World
In the words of Panthouse:
Victoria Burge's work explores geometric combinations and sequences of patterning through the language of maps and mathematical systems that appear in everyday contexts, such as children’s games, numeric series, or weavers’ draft notations. Order and seriality in Burge’s compositions are belied by a distinct presence of the artist’s hand through subtle, intentional irregularities that challenge and redirect the viewer’s eye. This palpable mark-making is a nod to the tactile, utilitarian source material from which she works.
For Grid Variation I - XX, Burge developed a stencil of 396 circles within a square grid that were laser-cut into Mylar. Each handmade paper piece within the edition is composed of a different combination of circles from this stencil. On top of each image, Burge made a unique drawing using pencil, graphite, and opaque inks.
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Testing the process and laser cut Mylar stencil at Dieu Donné.
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Grid Variation, 2019 (14 x 11 inches) is a varied edition of 20 co-published with Dieu Donné. For more information on the edition, click here.
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If you are in New York City over Thanksgiving, check out Victoria's exhibition at Planthouse.
Victoria Burge – Notations
October 17–November 30, 2019
Planthouse
55 W 28th St
New York, NY 10001
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