How UV printing works
A UV printer is an inkjet whose ink stays liquid until ultraviolet light hits it. A lamp beside the print head cures each pass as it lands, so the ink sits on top of almost any surface instead of soaking in, and it can be stacked into raised texture.
Step by step
- Jetting. A piezo inkjet head fires tiny drops of UV-curable ink onto the object on the flat bed, or onto a tumbler turning on a rotary attachment.
- Curing. A UV LED lamp riding with the head hardens the ink almost instantly.
- Underbase, color, varnish. On dark, clear or colored objects the printer lays down white first so the colors on top look right. Cyan, magenta, yellow and black make the image, and an optional clear varnish adds gloss or a matte finish and some protection.
- Texture. Printing cured layer on layer in the same places builds relief you can feel: 5 mm on the eufyMake E1, 7 mm on the xTool O1 Omni, and more on some crowdfunded machines.
Slick surfaces such as glass, metal, acrylic and some plastics need a thin primer or adhesion promoter first so the ink grips (OMTech, eufyMake). The materials guide goes through them one by one.
UV inkjet printing technology
Four parts do the work, and the makers differ mostly in how they build them.
- Print head
- A piezo inkjet head, usually made by Epson in these printers: the F1080 in the xTool O1 Omni, the OMTech Spectra A3+ and Morpho Standard, and the i3200 in the HeyGears G1 and G1X and Morpho Pro. The Epson SureColor V1070 uses Epson's own MicroPiezo head.
- Ink
- UV-curable ink, which stays liquid until UV light hardens it. Machines carry anywhere from six channels (CMYK, white and varnish) to eight on the HeyGears G1X and Morpho Pro and twelve on the dual-head Longer ePrint, so white can go down faster.
- Lamp
- A UV LED lamp that rides with the head and cures each pass as it lands.
- Height sensing
- The printer has to know how far the surface is from the head. The eufyMake E1 aligns with a camera, and the OMTech Spectra A3+ senses height with an infrared sensor.
Types of UV printing
Machines come in two sizes. A personal UV printer, which is what eufyMake and Longer call their desktop machines, has an A3-size bed or smaller and is made for one table; trade flatbeds are bigger, heavier and built for print shops. Past size, UV printing comes in a few types, set by how the object meets the ink.
| Type | How it works | Seen in |
|---|---|---|
| Flatbed | The object lies on a flat bed and the head passes over it. The usual way: phone cases, wood, acrylic, signs. | Every printer here. Beds run from 212 × 299 mm on the Epson SureColor V1070 to 350 × 450 mm on the OMTech Spectra A3+. |
| Rotary | An attachment turns a cylinder under the head, for tumblers, mugs and bottles. | eufyMake E1 (optional attachment, round objects 40-100 mm across); xTool O1 Omni (optional OR1 rotary); HeyGears G1 and G1X (objects up to 245 mm tall and 100 mm across). |
| Roll to roll | Film or flexible material is fed from a roll under the head. | eufyMake E1 with its roll attachment, and roll-to-roll and conveyor attachments for the Longer ePrint. |
| UV DTF transfer | The printer prints onto film, a laminator bonds the layers, and you peel and stick the result onto the object. | eufyMake sells a UV DTF laminating machine for the eufyMake E1, and the Longer ePrint comes in laminator combos. |
| Texture and relief | Layers are printed on top of each other in the same places to build raised, feelable relief. | 5 mm on the eufyMake E1, 7 mm on the xTool O1 Omni, up to 15 mm claimed for the Longer ePrint and up to 60 mm claimed for the Pro model of Morpho, whose software currently supports 5 mm. |
| Full-color 3D | Prints whole color 3D models using UV resin. | The HeyGears G1 and G1X Full-3D version. |
| UV plus fabric | A second head prints fabric inks for T-shirts and film transfers beside the UV head. | The xTool O1 Omni UV + DT Fabric edition, the Longer ePrint UV + DT and a HeyGears G1X fabric version. |
From the makers' own pages, linked on each printer's page. For prices and sizes see every printer compared.
UV printing against the alternatives
| Method | Works on | Color and white | Good for | Watch out for |
|---|---|---|---|---|
| UV printing | Hard goods: wood, acrylic, metal, glass, ceramic, leather, plastic | Full color plus white, so dark and clear objects work | One-offs and small batches of personalized objects, raised texture | Dear machines and ink; not for food-contact surfaces; can wear under heavy abrasion |
| UV DTF | Almost any hard surface, as a transfer sticker | Full color, white in the film | Curved or oversized items that won't fit under a flatbed | Needs a laminator; it's a sticker, not printed into the surface |
| Sublimation | Polyester fabric and polyester-coated blanks only | No white, so blanks must be white or light | Polyester shirts and coated mugs, cheaply per piece | No wood, bare metal, glass or dark items; needs a heat press |
| DTF and DTG | Fabric: cotton, polyester, blends | Full color with white | T-shirts and clothing | Not for hard goods, though some UV printers have a fabric edition that does both |
| Laser engraving | Wood, leather, acrylic, coated metal, glass (etched) | One tone: it marks the material itself | Permanent marks that can't peel or fade | No color |
| Ordinary inkjet | Paper, photo paper, printable vinyl | Full color, no white | Paper prints and stickers | Can't print straight onto objects |
Summarized from The Maker's Chest and OMTech.
Choosing between machines rather than methods? UV, DTF, sublimation or a Cricut sets out what each costs to run and who each suits.
Where UV ink falls short
- Cured ink is a hard layer, so it can crack on very flexible materials. Use flexible white where the printer offers it, or leave out the white on bendy leatherette.
- Very high heat can damage prints, and long spells of outdoor sun can fade them without protection.
- UV-printed surfaces aren't meant for direct contact with food (xTool, OMTech). Print the outside of a tumbler, not the rim or the inside.
Next: what to look for in a UV printer, or every printer side by side.