settings · stone & ceramic · slate · engrave only
Slate Laser Engraving Settings (5W–40W Diode Lasers)
On a 10W diode laser, engrave slate at 35% power, 1,500 mm/min (25 mm/s), one pass, no air assist. Slate is one of the easiest materials for a diode laser — the beam fractures the dark mineral surface to reveal a crisp bright-white mark. No masking, no prep. Invert your design in software so the areas you want white are dark in your file. Settings from LightBurn community forum and Bonny Creations; last verified 2026-06-26 — lasertinkerer.com
"On a 10W diode laser, slate engraves at 35% power, 1,500 mm/min — one pass, no air assist, no masking needed."
- 10W community anchor: 35% power, 1,500 mm/min, 1 pass, no air assist — Sculpfun S30 Pro 10W (LightBurn forum)
- Slate creates bright white marks — no paint, masking tape, or marking spray required
- Too much power causes a yellow-orange tinge (iron oxidation at excessive temperatures) — keep power below the sweet spot
- Invert your design in LightBurn before engraving — engraved areas appear white, background stays dark grey
- Oil the surface after engraving (mineral oil or 3-in-1 oil) for deeper contrast and surface protection
What power and speed engrave slate on a 10W diode laser?
A 10W machine like the Sculpfun S30 Pro 10W or xTool D1 Pro 10W engraves slate coasters in a single pass. The settings are more moderate than you'd use for wood — slate doesn't need as much energy to fracture as wood needs to burn.
Machines: Sculpfun S30 Pro 10W, xTool D1 Pro 10W, Ortur LM3. Clean white mark in one pass. Confirm with a test grid — exact power may need ±5% adjustment for your specific slate batch.
Slate engraving settings by wattage — diode lasers 5W to 40W
All settings: single pass, no air assist, fill mode (vector or image). Speed in both mm/min and mm/s. The 5W row is wattage-scaled from the 10W community anchor — it is an untested estimate. Confirm any setting with a test grid on your specific slate before committing to a batch.
| Wattage | Example machines | Speed mm/min | Speed mm/s | Power % | Passes | DPI | Air assist | Confidence / Source |
|---|---|---|---|---|---|---|---|---|
| 5W | xTool D1 5W, Sculpfun S5 | 1,000–1,500 | 16–25 | 60–75% (est.) | 1 | 254 | Off | Estimated wattage-scaled from 10W anchor — unverified, confirm with a test grid |
| 10W | Sculpfun S30 Pro 10W, xTool D1 Pro 10W | 1,500 | 25.0 | 35% | 1 | 254 | Off | Confidence: low Community · LightBurn forum t/92668, user Ronjon1163 (Sculpfun S30 Pro 10W) |
| 20W | Atomstack X20 Pro, xTool D1 Pro 20W | 3,500–4,000 | 58–67 | 50–60% | 1 | 300 | Off | Confidence: medium Community · Bonny Creations settings library (Atomstack X20 Pro 20W) |
| 33W | Sculpfun S30 Pro Max, xTool S1 33W | 3,000 | 50.0 | 65–70% | 1 | 300 | Off | Confidence: medium Community · Bonny Creations settings library (Sculpfun S30 Pro 33W) |
| 40W | xTool S1 40W, xTool D1 Pro 40W | 3,000–3,500 | 50–58 | 70–80% | 1 | 300 | Off | Confidence: medium Community · Bonny Creations settings library (xTool S1 40W) |
EI = (power_pct × W_optical × 0.6) / speed_mm_min (Laser Tinkerer Energy Index). Note: slate EI does not normalize linearly with wattage the way wood does — see the power trade-off section below. Always run a material test grid before production.
Energy map — 10W slate engraving (power vs speed)
The map below shows the parameter space for a 10W diode on slate. The ringed cell (35% power, 1,500 mm/min) is the community-verified sweet spot. Lower-left cells are too cool — the mark will be faint or absent. Upper-right cells are too hot — expect a yellow-orange tinge instead of clean white.
Energy density map for 10W diode on slate. Horizontal axis = power percentage. Vertical axis = speed in mm/min (slower = more energy). The ringed cell shows the 35% / 1,500 mm/min community-verified sweet spot. Run a test grid to find your exact sweet spot — slate batches vary.
How slate engraving works — and why power matters more than you think
Slate is a metamorphic rock made mostly of clay minerals and mica, with varying amounts of quartz and iron compounds. The dark grey colour comes from fine particles of graphitic carbon and iron sulphides. When your laser beam hits the surface:
- At the right power level: the beam heats the surface just enough to fracture the mineral grains (micro-fracturing) and oxidise the dark iron compounds to lighter iron oxides. The result is a rough, light-scattering surface that looks bright white.
- Too little power: the beam barely warms the surface — you get a faint grey mark or nothing visible at all. This is the "too cool" zone in the heatmap above.
- Too much power: the beam drives iron oxidation past the pale iron(III) oxides into reddish-brown or yellow iron compounds (goethite, haematite). Instead of white, you get a yellow-orange mark. This is the most common beginner mistake on high-wattage machines.
The community data on this page shows something unexpected: the Laser Tinkerer Energy Index does not normalize consistently across wattages for slate. The 10W and 20W rows have very similar energy density (EI ≈ 0.0014–0.0017). But the 33W and 40W community settings are 3–4× higher (EI ≈ 0.0045–0.0064). This may reflect production operators optimising for speed at the expense of mark gentleness. If you have a 33W or 40W machine, consider starting with a lower EI first — try 70% power at 5,000 mm/min — and only increase if the mark is too faint.
The "invert your design" step
This is the single most common source of confusion for slate beginners. Remember: the laser engraves what is dark in your design file, and engraved slate appears white. So to get white text on a dark slate background, your design must show dark (filled/black) text.
- In LightBurn: select your image layer → Edit → Invert Image. Or start with a black-filled design from scratch.
- For vectors (logos, text): fill them with black. The laser will engrave the filled areas, which become white on the slate.
- For photos: convert to grayscale, then invert. Bright areas in your photo will become the engraved (white) areas on the slate.
DPI and line interval for slate engraving
For slate, a line interval of 0.1 mm (254 DPI) is a safe starting point for most artwork. The community data at higher wattages suggests 300 DPI also works well. Going much finer than 400 DPI is rarely worth it — slate's micro-fractured surface doesn't resolve fine dot patterns clearly.
| DPI | Line interval | Best for | Notes |
|---|---|---|---|
| 200 DPI | 0.127 mm | Large logos, bold text, coasters | Fastest. Slight line texture visible up close. Fine for most projects. |
| 254 DPI | 0.100 mm | General purpose — graphics, text, portrait silhouettes | Good all-round balance of speed and detail. Recommended starting point. |
| 300 DPI | 0.085 mm | Photo engraving, fine artwork | More detail, slightly longer run time. Used by the majority of community reports at 20W+. |
| 400 DPI | 0.063 mm | Highly detailed photographs | Rarely needed. Run time increases significantly. Results depend heavily on beam focus quality. |
For photo engraving on slate: use grayscale or dithering mode in LightBurn, inverted, at 300 DPI. Slate gives excellent photo results because the white marks have very high contrast against the dark background — you get naturally deep apparent dynamic range without any post-processing.
Preparing slate and finishing after engraving
Before engraving
- Clean the surface: wipe with a damp cloth to remove dust and oils. Fingerprints can absorb some beam energy and leave faint marks.
- Flat is important: slate coasters are usually flat enough, but if your slate has a raised texture or is warped, your focus height will vary and settings may need adjustment.
- No masking tape: unlike wood, slate does not need masking tape to prevent surface scorch marks. The laser marks the slate directly and cleanly.
After engraving
- Wipe with a damp cloth: remove the fine white mineral dust from the engraved area. Use damp, not dry — a dry cloth can scatter dust into the air.
- Apply a thin coat of mineral oil or 3-in-1 oil: rub into the slate surface with a cloth, then buff off the excess. The oil darkens the unengraved background, making the white engraving stand out dramatically. The mark itself stays white. This step is optional but makes a noticeable difference in contrast.
- Felt pads on the base: if you're making coasters, stick self-adhesive felt pads to the bottom to prevent scratching furniture.
Common mistakes when engraving slate
| Problem | Most likely cause | Fix |
|---|---|---|
| Yellow or orange mark instead of white | Power too high or speed too slow | Reduce power by 10–15%, or increase speed by 500 mm/min and test again |
| Very faint or no visible mark | Power too low, speed too fast, or focus off | Increase power by 5–10%, re-check focus height, or slow speed to 1,200 mm/min |
| Design appears reversed (dark where you wanted light) | Forgot to invert the design | Invert the image/fill in your software. Engraved areas = white on slate. |
| Uneven mark (darker on one side) | Slate not perfectly flat, or focus varies across the bed | Check focus with a ramp test. Use a flat honeycomb bed to ensure level contact. |
| Rough or splattered edges on fine lines | Too much power causing micro-chipping | Reduce power and optionally add a second contour-only layer at reduced power to clean up edges |
Every slate batch is different — the mineral content and surface hardness vary. The settings on this page are community-verified starting points. Before engraving your actual project, run a small test grid with power ranging from 25% to 55% and speed from 1,000 to 2,500 mm/min on a corner of your slate or a test piece. The free test-grid generator produces a downloadable SVG and firmware-aware G-code for exactly this purpose.
Generate a slate test grid →Frequently asked questions about slate laser engraving
Do I need air assist to engrave slate?
No. Turn air assist off for slate. Air assist is designed to clear combustion debris from a cut, but slate doesn't burn — it fractures. The air stream just scatters the fine mineral dust and cools the spot, which can reduce mark quality. After engraving, wipe the slate with a damp cloth to remove any loose dust.
Why does my slate engraving look yellow instead of white?
Too much energy. The ideal mark is a crisp white from micro-fracturing. Excessive heat drives the reaction further — iron compounds in the slate oxidise to reddish-brown or yellow compounds (haematite, goethite) instead of the lighter iron oxides you want. Drop power by 10–15% and test again.
Do I need to invert my design for slate engraving?
Yes, almost always. The laser engraves what is dark in your design — and engraved slate appears white. So if you want white text on a dark slate background, your design file should show dark (black) text on a white background. In LightBurn, use Edit → Invert Image on photo layers, or fill your vector text with black.
Can a diode laser cut through slate?
No. Slate is a metamorphic rock — no home-class diode laser can cut through it. The laser can only engrave the surface. For slate coasters, you buy pre-cut blanks in the shape you want, then engrave them. This is the standard workflow for coaster and tile projects.
How do I make the engraving more contrasty?
After engraving, wipe with a damp cloth to remove dust, then rub a thin coat of mineral oil or 3-in-1 oil into the surface and buff off the excess. The oil deepens the dark background without affecting the white mark, significantly increasing the apparent contrast. The result looks more polished and professional than the raw-engraved surface.
Where to find slate blanks and safety gear
Links below are Amazon search links. As an Amazon Associate I earn from qualifying purchases — this helps keep the site free.
Material
Slate coaster blanks
Pre-cut slate coasters for laser engraving — usually sold in packs of 10–50. Look for 10×10 cm or 4×4 inch sizes. Natural slate will have slight colour and texture variation between pieces.
Find slate blanks →Safety
OD7+ laser safety glasses
Required for any diode laser work. Make sure glasses are rated OD7+ at 450 nm (the diode wavelength). These are significantly cheaper than a corrected-vision prescription and are required whenever the laser is running.
Find OD7+ glasses →Finishing
Mineral oil or 3-in-1 oil
A small amount rubbed into engraved slate darkens the background and dramatically improves contrast. Any food-safe mineral oil or general-purpose 3-in-1 oil works. Only a tiny amount is needed — a small bottle lasts for hundreds of coasters.
Find finishing oil →Related guides
- Anodized aluminum engraving settings — another no-masking engraving material with crisp permanent marks
- Leather engraving settings — veg-tan leather for wallets, keychains, and coasters
- Material test-grid generator — free tool to find your exact settings for any material
- Laser Tinkerer Energy Index — how settings are normalized across wattages
- Sourcing and confidence methodology — how numbers get on this site
- Ceramic tile engraving settings — similar surface-marking material; requires TiO2 or Cermark coating, air assist off
- Can a diode laser engrave glass? — related capability question (ceramic tile also works via similar mechanism)
- Can a diode laser engrave slate? — full capability guide including the invert-design rule, oil finishing technique, and physics explanation