My lithophane looks wrong: dark, washed out, blurry or striped

First, the four settings behind most problems

Check these in your slicer before anything else. The rest of this page goes symptom by symptom. The lithophane maker shows a “lit from behind” preview for your filament, so you can see most of these problems before you print.

It’s too dark, or you can barely see the picture

• The light is too weak or too far away. A lithophane needs a bright, even light 2–5 cm behind it. Daylight through a window works for testing; a dim bulb across the room doesn’t.
• The thickest parts are too thick for your light. Every extra millimetre of plastic lets through only a fraction of the light. Bring the maximum down to about 2.4–2.6 mm, or use a brighter light.
• The photo is dark. Dark photos make thick, dark lithophanes. Raise the brightness, or keep auto levels on so the darkest and lightest parts of the photo use the full thickness range.
• The filament isn’t white. Even light grey or cream filament blocks much more light.

It’s washed out, with no contrast

• The thickness range is too small. If the thinnest and thickest parts are close (say 0.8 and 2 mm), there’s little difference between light and dark. Go up to about 3–3.2 mm at the thick end.
• The filament lets too much light through. Clear, translucent and silk filaments glow everywhere. Use matte white PLA.
• The light is too close or too harsh. A bare LED right behind the print burns out the bright areas and leaves a hot spot. Move it back or put a diffuser (a sheet of paper works) between them.
• The brightness mapping is linear. Plastic doesn’t dim light in a straight line, so a straight brightness-to-thickness mapping crushes the shadows and flattens the rest. The lithophane maker’s default “True light” mapping corrects for that.

There are dark lines, stripes or blotches

• Infill under 100%. The most common cause by far. Hollow areas show as a dark pattern when lit.
• Gaps between the walls and the inside. If lines run along the outline, add a wall or raise the infill overlap so walls and infill fuse.
• Even stripes across a print standing up. That’s usually the printer itself (Z wobble or uneven layers), and the lithophane makes it visible. Printing flat avoids it.
• Wavy steps in smooth areas (a sky, a wall). The layers are too thick for the shading. Lower the layer height to 0.12 mm or less.

It’s blurry, or the detail is soft

• Flat or upright? Printed flat, every shade of grey is a whole number of layers, so a 0.12 mm layer gives about 18 shades between 0.8 and 3 mm. Printed standing up, the thickness comes from the nozzle’s sideways movement instead, which allows finer steps and more detail, but the thin panel needs a brim and slow speeds. Flat is the more reliable choice; upright can be sharper.
• The nozzle sets the finest detail. A 0.4 mm nozzle can’t draw features much smaller than about half its width. A 0.2 mm nozzle shows finer detail, and the lithophane maker’s detail setting follows your nozzle.
• The lithophane is small. A face 15 mm wide has very few lines to work with. Print bigger: a 100 mm wide lithophane is a good minimum for portraits.
• The photo is soft or tiny. About 1,000 pixels across is plenty, but a 300-pixel thumbnail won’t do. Crop to the subject so the face fills the frame.

It has holes, or bright spots that shine straight through

The thinnest parts are too thin to print solid. Keep the minimum at 0.8 mm. Going thinner makes brighter highlights but risks gaps.

It warped, or fell over while printing

• Upright prints: add a brim, slow down, and keep the frame on: it makes the panel much stiffer. A curved lithophane stands more steadily than a flat one.
• Near a light: PLA softens at around 60 °C. Use an LED, never a hot bulb.

Text or a face looks backwards

You’re looking at it from the other side. Turn the lithophane around, or use the maker’s mirror option before exporting so it reads correctly from the side you’ll display.