Relief and texture: tactile 3D effects in UV printing

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A UV printer can do more than print flat. Because every ink layer hardens immediately, you can stack layer upon layer until a tactile structure forms. This is how oil painting reproductions get brush strokes, signs get raised lettering and wood prints get a noticeable grain.

How relief is created

The principle is simple: the printer passes over the same spot several times and builds ink upward. Each layer is cured before the next one goes on. Where there are more layers, the surface is higher.

There are two common ways to build it up:

• White as the body, colour on top: Many layers of white form the shape, and a CMYK layer colours the surface. Result: coloured relief.
• Varnish as the body: Many layers of clear varnish. Result: a transparent, glossy structure over a flat colour print, for example for spot varnish effects or a water-drop look.

With the E1, for example, eufyMake describes exactly these two modes: coloured texture from white layers with a colour layer on top, and gloss texture from varnish layers. The basics of layer order are in Colour, white and varnish.

How high can it go?

That depends heavily on the device. For simple spot varnish effects, fractions of a millimetre are enough, and that is already clearly tactile. Devices that specifically advertise relief state considerably more. For the E1, eufyMake gives a maximum relief height of up to 5 mm.

Such values are maximums. In everyday use, far less than the maximum is enough for most motifs to give a clear tactile structure. Work your way up with test prints. Before buying or starting a project, always check the manufacturer’s specifications for your device and whether it supports relief in the software at all. Not every UV printer with a varnish channel offers a dedicated texture mode.

Time and ink needs

Relief is the most expensive effect in UV printing. Every millimetre of height consists of many individual layers, and each layer needs its own pass.

• Time: A large-area, high relief can take many times as long as a flat print. A small raised logo, on the other hand, is done quickly.
• Ink: Consumption rises with area times height. Because white or varnish usually forms the body, most of the usage is those.

Tips for saving:

• Raise only the areas that really need to be tactile, rather than lifting the whole area.
• Leave the background flat. eufyMake, for example, offers a mode that reduces the background height.
• Choose the lowest height possible. The visual difference between 0.5 and 2 mm is often smaller than the difference in consumption.

The printer software usually shows an estimate of time and ink before printing. Use it to compare different heights.

Setting up files: the height map

You usually control the height via a greyscale image, known as a height map:

• Light means high, dark means flat (or the other way round, depending on the software, often switchable).
• The height map has the same size and position as the colour motif.
• Soft gradients give gentle hills, hard edges give steps.

Here is how to proceed:

1. Finish the colour motif.
2. Make a copy and convert it to greyscale, or paint the height by hand.
3. Adjust the contrast: depending on the software, light or dark areas get more height. Check this in the manual or with a small test print and adjust the image accordingly.
4. Smooth out fine interference, for example with a slight blur. Noise in the grey image would otherwise become pimples in the relief.
5. Load it in the printer software as a texture layer, set the height and check the preview.

Some programs generate the height map automatically from the brightness of the photo. This is quick, but not always right: a dark sky becomes flat and a white cloud high, even if that is not what you want. For good results, a custom height map is worthwhile. More on file preparation in Preparing print data.

Application ideas

• Painting reproductions with brush texture
• Raised lettering on signs and door signs
• Wood grain, stone look or leather embossing on smooth boards
• Spot varnish on business cards and packaging samples
• Tactile elements on game boards or learning materials
• Decorative phone cases with a pattern

Limits

Durability: Tall structures stand exposed and take more from knocks and rubbing. Cured ink is rather hard and brittle. Relief can chip off when bent or struck.

Edges: Vertical walls are hard to print. Ink spreads minimally before curing, so edges on tall relief easily become rounded or untidy. Very fine, tall details such as thin lines come out worse than broad shapes.

Colour on the flanks: The colour layer sits on top. On steep flanks, the white of the layer below can show through.

Substrate: Relief needs a stable, well-adhering base. On glass or smooth metal without primer, a thick relief comes loose more easily than a thin colour print.

Food and skin contact: More ink also means more material that has to be fully cured. Relief does not belong on surfaces that come into contact with food.

For business use

Relief sells well because customers can touch it. Calculate the surcharge carefully, though: time and ink rise considerably. Print samples at different heights to find, for each product, the point where the effect is convincing without being needlessly expensive. For products that are handled a lot, flat relief with varnish is more durable than tall structures.

Continue with: Colour, white and varnish and Product ideas for UV printing.