How durable is UV printing? Scratches, sun, water and the dishwasher
are explained briefly when you hover over or tap them.
Once cured, a UV print is dry, touch-proof and considerably more robust than an ordinary inkjet print. It is not indestructible, though. How long it lasts depends less on the printer than on the ink, substrate, primer and protective varnish, and on how the finished part is used.
Scratch resistance
Cured UV ink forms a solid layer on the surface. It does not soak in as it does with paper or textile. This has two consequences: it is quite resistant to normal use, but if adhesion is poor it can flake off as a whole or be scratched off.
What determines scratch resistance:
| Factor | Effect |
|---|---|
| Ink type | Hard (rigid) ink is more scratch-resistant, flexible ink handles bending better |
| Primer | Often decisive for adhesion on glass, metal and smooth plastics |
| Varnish | Protects the colour layer from abrasion |
| Curing | Incompletely cured ink stays soft and delicate |
| Substrate | Greasy or dirty surfaces hold less well |
eufyMake names missing primer as the most common reason for peeling prints and says that a layer of varnish can double durability. More on this under Primer and Varnish.
A simple test for your products: wait 24 hours after printing, then press a piece of adhesive tape on firmly and pull it off with a jerk. If colour comes off, adhesion is not yet right.
Light and weather: indoors and outdoors
UV inks are pigmented and fairly lightfast. Outdoors, however, sun, rain, frost and temperature changes act together. Manufacturer figures:
- Roland DG states that its ECO-UV ink lasts up to two years outdoors if a gloss layer is applied as a finish.
- eufyMake gives 3 to 5 years for indoor prints, 1 to 2 years for unprotected outdoor signs and 2 to 3 years for laminated or protected signs.
These are guide values from the respective manufacturer for its inks. Other inks may perform better or worse. Check the data sheet of your ink. South-facing positions, high altitude and salty air shorten durability.
Behind glass or indoors without direct sun, a UV print lasts considerably longer than outdoors.
Water and moisture
Cured UV ink is waterproof. Rain or a damp cloth will not harm it. The edges are where it becomes problematic: if water acts for a long time, it can creep under a poorly adhering layer. The print then lifts from the edge.
With wood, the material itself also swells and moves. A printed wooden surface should not be left outdoors permanently unless the wood is protected all round. More on this in Printing on wood.
Dishwasher: generally no
Printed mugs, drinking bottles or cups are usually not suitable for the dishwasher. Heat, aggressive detergents and the water jet attack the adhesion. eufyMake expressly advises hand washing. The US retailer JPPlus writes in its instructions for UV-printed ceramic mugs: wash by hand only with mild washing-up liquid, not in the dishwasher.
A second question concerns food. JPPlus recommends not letting printed surfaces come into contact with food. For that reason, do not print on surfaces that come into contact with food or drink, for example the drinking rim of a mug, unless the ink used is expressly approved for this purpose.
Cleaning
- Soft cloth, lukewarm water, a little mild washing-up liquid
- No abrasives, scouring pads or steel wool
- No solvents such as acetone or cellulose thinner. Some inks tolerate isopropanol; this is stated in the data sheet
- Do not scratch, do not use a pressure washer
How to make the print last longer
- Degrease the substrate thoroughly before printing
- Use primer where the material needs it
- Choose the right ink: hard for rigid parts, flexible for bendable parts
- Make sure curing is complete
- Print varnish as a protective layer, especially on parts that are handled often
- For outdoors: choose material, ink and finish for outdoor use
What you should tell customers
Clear care instructions save you complaints. A short slip of paper or a sentence in the product description is enough:
- Clean by hand only, not in the dishwasher
- Wipe with a soft cloth and mild washing-up liquid, no abrasives
- Do not leave permanently in water
- For outdoor use: limited durability, no permanent direct sun if possible
- Do not use the printed surface as a cutting surface or a stand for hot items
For business
Do not promise durability in years that you cannot prove yourself. Better to word it cautiously (“for indoor use”, “dishwasher safe: no”). Test new materials with adhesive tape, cleaning and, if intended for outdoors, a test piece in a sunny spot. Complaints about flaking colour almost always have to do with adhesion, not with light. You will find help with this under Ink does not adhere.
Continue with: Varnish in UV printing and What does a UV print cost?