A dark mark: smoky gray, charcoal, or black. The workhorse for logos, text, and serials. A softer gray. Lighter contrast than a dark mark, often smoother and faster to run. Matte, satin white. Looks the same from every angle. Think the back of a MacBook, or frosted glass. Mirror-bright. Flashes when it catches the light, fades from the wrong angle. Angle-dependent by nature. Oxide colors like gold, bronze, blue, purple, and rainbow. A thin transparent film bending light, tuned by heat. Real depth you can feel with a fingernail. Survives abrasion. Costs passes and time. Fully severs the material. Each cell asks the same six questions of that material and that laser, and the answers come straight out of our physics model rather than from a chart somebody typed by hand. Open Why in any cell to read the reason in full. Material names in dotted underline have a full breakdown below. The material does it and the physics model says so plainly. It works, but something has to be true first. The condition is in the reason. A physical reason blocks it, and the reason is named. We have not modeled it yet. That is a gap in our data, not a claim that it is impossible. Answers tagged Measured come from our own test grids. Answers tagged Literature come from published material behavior, so treat those as a starting point and confirm them on a test card. A few materials at the bottom of the chart are not in the physics model yet and still show our hand-written answers. Bare aluminum with Diode Bare aluminum with CO₂ Bare aluminum with Fiber Bare aluminum with Fiber MOPA Bare aluminum with UV Stainless steel with Diode Stainless steel with CO₂ Stainless steel with Fiber Stainless steel with Fiber MOPA Stainless steel with UV Mild / carbon steel with Diode Mild / carbon steel with CO₂ Mild / carbon steel with Fiber Mild / carbon steel with Fiber MOPA Mild / carbon steel with UV Cast acrylic with Diode Cast acrylic with CO₂ Cast acrylic with Fiber Cast acrylic with Fiber MOPA Cast acrylic with UV Extruded acrylic with Diode Extruded acrylic with CO₂ Extruded acrylic with Fiber Extruded acrylic with Fiber MOPA Extruded acrylic with UV Wood & plywood with Diode Wood & plywood with CO₂ Wood & plywood with Fiber Wood & plywood with Fiber MOPA Wood & plywood with UV The chips above answer whether a mark is possible. The full map answers it with numbers: the speed, power, and pulse settings that reach each outcome on your machine. Blue light. Common, affordable, gantry. Great on wood. Bounces off bare metal and passes straight through clear acrylic. Infrared. The organics workhorse for wood, acrylic, leather, and glass. Reflects off bare metal, so it needs a marking spray there. Standard fiber. Built for bare metal marking and engraving. No pulse-width control, so no color. Fiber with a tunable pulse width. Everything standard fiber does, plus oxide colors on steel and finer control.

Cold light. Marks almost anything with very little heat: glass, plastics, coated metals. Expensive, and usually low power. Material breakdowns The full story on each material: what each mark really is, what's physically happening, and the honest limits. The stuff no settings chart tells you. Reflects about 91% of fiber light, so every mark is a surface texture. That is why they all shift with viewing angle, and why it never goes truly black. Bare aluminum is one of the trickiest metals to mark, and it is worth understanding why before you burn anything. Polished aluminum reflects about 91% of a fiber laser's light, so your beam mostly bounces off. Every mark below works by changing the surface so it stops bouncing light back the same way. That is the whole game. It also means every mark on bare aluminum is a texture, and textures look different depending on the angle you view them from. Keep that in mind. It explains almost everything that surprises people about this material. Drag the block to spin it. The frosted white mark The bright polished mark The deep engrave True black, and steel-style rainbow colors. Both come from oxide-film chemistry that aluminum does not have. If someone shows you jet black on 'aluminum,' it is almost always anodized aluminum, which is a different material as far as the laser is concerned, where the coating does the darkening. Bare aluminum mostly ignores diode and CO₂ lasers. The reflectivity that makes fiber marking tricky makes diode and CO₂ marking nearly impossible. You will get a faint smudge at best. If you have a diode or CO₂ and need to mark aluminum, use anodized stock or a marking spray. Stainless steel The richest metal for marks. Grows real oxide-interference colors, goes genuinely black by annealing, and takes a deep engrave, all with no coating. If aluminum is the frustrating metal, stainless is the generous one. It does everything aluminum cannot. The reason is chemistry: stainless has chromium in it, and chromium loves oxygen. Heat the surface with a laser and it grows a thin, clear oxide film, and the thickness of that film is something you can dial with heat. Thin films bend light into colors. Thicker films go black. None of it removes metal, so the part stays smooth and rust-resistant. This is the exact trick TRUMPF says works on steel and titanium but not aluminum, which is why stainless can hit a full rainbow and true black while bare aluminum tops out at gray. Drag the block to spin it. The oxide rainbow The black anneal The frosted white / etch The deep engrave Perfectly repeatable color across different machines. Because color tracks pulses-per-area, a gold recipe from one MOPA will not land as gold on another without re-tuning. Colors are also heat-reversible above about 200°C, and they read best in daylight rather than under narrow-spectrum LED light. CO₂ and blue diode do almost nothing to bare stainless. CO₂ light reflects off it, and a diode's spot is too spread out to reach the oxide-color heat, so both effectively need a marking spray like Cermark to leave a legible black. That is a coating on top, not the stainless-oxide magic above. UV can make colors and fine white marks by a different route, but at low power, so it is a precision tool, not a fast or deep one. Anodized aluminum A hard dyed oxide skin over aluminum. Marks beautifully where bare aluminum fights you. Most lasers strip it to bright metal, and MOPA can fracture underneath for a durable black. Anodized aluminum is a completely different animal from bare aluminum, even though the metal underneath is the same. Anodizing grows a hard, slightly porous oxide skin on the surface, then dyes and seals it. That skin absorbs laser light well, which is exactly what bare aluminum refuses to do. So the thing that makes bare aluminum hard, its mirror-like reflectivity, is hidden under a coating that marks easily. Almost every mark here is really about that coating: taking it away, or changing it, rather than touching the metal. Drag the block to spin it. The coating-strip mark (bright silver) Color and tone shifts Real depth engraving. The coating is only a few thousandths of a millimeter thick, and once you are through it you are back to fighting bare aluminum. Photographic grayscale is also weak here, because the coating responds in steps rather than a smooth ramp. Dithering, not power ramps, gives the best tone. This is the happy exception where almost every laser works. Diode does great on dark anodize but struggles on pale colors, because it needs the dye itself to absorb the blue light (a black dye drinks it in, a gold dye reflects it). CO₂ does clean silver removal and nothing else. UV works on any color and gives the finest detail, just slowly. Only MOPA reaches the true durable black. The engraver's favorite plastic. Frosts bright white when engraved, and flame-polishes to a clear glossy edge when cut with CO₂. Acrylic and a CO₂ laser are a perfect match, and it comes down to one fact: the CO₂ beam is tuned to a wavelength that acrylic drinks in completely, no matter what color the sheet is. All the energy lands in the top layer and the plastic vaporizes cleanly back into gas rather than charring like wood. That clean vaporization is why acrylic cuts glassy and engraves bright white. One thing to know up front: there are two kinds of acrylic, cast and extruded, and they behave differently under the laser (more on that below). Cast is the one you want for engraving. Drag the block to spin it. The frosted white engrave The flame-polished cut edge Deep engrave & relief You cannot un-frost a mark, and you cannot laser acrylic in full color (a laser only removes material, it does not add pigment; color acrylic graphics come from UV printing, with the laser doing the cutting). And settings never transfer between cast and extruded acrylic, or reliably between brands and thicknesses, so always test on scrap. Here is the big one: clear acrylic is nearly invisible to a blue diode. The blue light passes straight through like a flashlight through a window (only about 8% is absorbed), so a diode does nothing to clear stock no matter how much power you throw at it. A coat of paint or masking tape gives it something to grab, but that is a workaround, not a fix. Diodes do cut dark and black acrylic, though the edge comes out rough and bubbly rather than polished. Fiber and MOPA pass straight through clear acrylic too, and only mark dark pigmented sheets. UV cuts and frosts beautifully with no yellowing, just slowly and at low power. Two plastics look almost exactly like acrylic and are dangerous to laser. Polycarbonate (often sold as Lexan) melts, yellows, and can catch fire instead of cutting clean. PVC or vinyl mislabeled as 'clear plastic' releases chlorine gas that corrodes your machine and is genuinely hazardous to breathe. If you are not certain a clear sheet is acrylic, do not run it. A quick scrap flame test tells you: real acrylic burns clean, these do not. A tone ladder from light toast to deep char, which is exactly why photo-realistic engraving works on wood. Grain and moisture make every board a little different. Wood is the friendliest material on this whole list, and it comes down to one thing: heat browns wood gradually. It is not an on-or-off switch. A little heat toasts it tan, more turns it brown, more still burns it black. Because that is a smooth ramp of real shades and not a single threshold, wood can hold a photograph, which bare aluminum simply cannot. The catch is the flip side of what makes wood great: it is a natural material. Grain, moisture, and species all change the result, so wood needs testing on scrap more than almost anything else here. Drag the block to spin it. The tone ladder: toast, brown, and photo engraving Deep engrave & relief Color. Wood only does tan through black, because the mark is browned wood, not pigment. And it cannot give you a recipe that transfers cleanly from board to board. Grain, moisture, and species all shift the result, which is the whole reason wood rewards a quick test on your actual stock. CO₂ is the reference tool for wood and works the same on every species and color. A diode is popular and genuinely good here, especially on dark woods and dithered photos, just slower and more prone to charring. Fiber and MOPA are the wrong tool: their light does not couple to wood, so you get uncontrolled scorching at best. UV is clean and precise but low-power and slow. MDF and plywood are bonded with glues that release formaldehyde when burned, so run good filtered extraction. Never laser pressure-treated lumber (it can release arsenic and chromium) or unknown painted or laminate-faced boards. Oily exotics like cocobolo and pitch-heavy softwoods can flare up at resin pockets. And never leave a running wood job unattended, because wood catches fire. This is Stage 1. Next comes finding your settings. Picking your mark is where the Test Lab starts. Getting the exact settings for your machine, dialed in and saved for good, is what the next four stages do. They walk you through finding, tuning, and confirming the recipe for the mark you chose here.