Dark materials in laser engraving

Five of the 12 profiles invert by default: dark slate, clear glass, frosted glass, clear acrylic and dark plastic. Dark or coloured acrylic deliberately does not, a choice made from practice. Leather, the woods, anodized aluminum and stainless steel do not invert either. The default is only a starting point; the Invert control flips it either way.

• Invert: dark slate, clear and frosted glass, clear acrylic, dark plastic
• No invert: dark/coloured acrylic, leather, woods, anodized aluminum, stainless steel
• Invert control overrides the default

On a light material the laser darkens, so shadows become mark. On slate, glass or a dark plastic the engraved area reads lighter than the surface, so the bright parts of the photo are the parts engraved. A positive file then looks like a negative. Check the live preview and, when you are not sure, engrave a small test normal and inverted.

• Light material: shadows become the mark
• Dark or frosted: bright parts become the mark
• Small test settles it

A light mark on a dark ground loses delicate grey tones quickly. Keep the subject simple, give faces strong edges, and remove a busy background. Closed shadows in the source and dot gain both make the result heavier than the preview suggests.

• Simple subject, strong edges
• Remove a busy background
• Allow for dot gain

Settings differ by material, colour and laser, so none are given here. Engrave a material test grid on scrap of the same material, choose the best field and save it as a recipe. For one metal with a light mark on a dark anodized layer, see the anodized aluminum guide.

• Test grid on scrap
• Save the best field

The fastest way to avoid a wasted piece is to look at both versions before engraving. Open the live preview, switch Invert on and off, and ask which one shows the face or logo the way it will look on the finished surface. Then confirm with a small physical test on scrap, because the preview shows the file, not how your material reacts. Record the result in a recipe, so the next job on that material starts from the right default.

• Switch Invert on and off in the preview
• Confirm with a small test on scrap
• Save the choice in a recipe