If you have been in the wide format print industry for a while then you will know when it comes to printing, there are many options available, each with their own unique characteristics and advantages.
Two popular printing technologies are eco-solvent and UV.
If you are not familiar with these types of technologies, keep reading. We will explore the key differences between them and when you might choose one over the other.
Before we look at the differences, let's have a quick look at the similarities. Below is a picture of two printers, the one on the left is an eco-solvent printer, and the one on the right is a UV printer.
Both print with liquid ink through a piezo printhead.
Both can be configured with cyan magenta yellow and black.
Both print roll-to-roll, meaning the media you feed into the printer comes on a roll and is mounted on the back of the printer, then it travels through the printer to the front and can be attached to a 'take-up' device and rolled back up again.
They are both capable of printing onto a wide range of media including SAV (self-adhesive vinyl), banner stock, canvas, PP (polypropylene), wallpaper, textiles, specialised paper, etc.
And prints from both can be used for similar applications including artwork reproductions, window graphics, stickers, pull-up banners, light boxes, signage, the list can go on and on.
So if they seem so similar, why do we need both?
Let's look at the differences.
Eco-solvent ink
Eco-solvent is a mature technology and is generally available at a lower cost than UV. It has a lot of media options allowing it to be used for a diverse range of applications. It became very popular with signwriters due to its weather resistance and outdoor longevity and although over-laminating will protect the print and extend its outdoor life, a print not needing to be chemical resistant or requiring more than roughly 3 years of outdoor life can simply be printed and sent for installation. Vehicle wrappers prefer eco-solvent too, thanks to its ability to retain colour density when being stretched over various contours.
Eco-solvent ink is generally available in cyan, magenta, yellow, and black which can create millions of colours, but can also include special colours such as light cyan, light magenta, light black, and orange. Spot colours such as silver and white may also be available but are not very popular due to causing a substantial decrease in print speed and less-than-ideal results in opacity (for white) and reflectiveness (for silver).
Special media is also required for eco-solvent printing because the ink partially migrates into the media. The advantage of this is the print has good rub resistance and also takes on the surface qualities of the media. eg matte, gloss, metallic. If it isn't a 'solvent media' the ink may absorb in and run through the media or sit on the surface and not dry which can happen with some PP products.
Eco-solvent printers require heaters to prepare the media for printing, controlling dot gain, and drying the print. Most eco-solvent printers will have three heaters: pre-heater, platen-heater, and post-heater, and depending on the print speed and media type will often be set to around pre: 35-45°C, platen: 35-45°C, and post: 45-50°C.
Out-gassing is a necessary process with eco-solvent printing. This takes place during the first 24 hours after printing and is when the solvent portion within the ink evaporates. During this time it is recommended not to over-laminate the print as delamination can occur. It is also recommended not to cut within the printed area because as the solvent evaporates the surface tension changes and the image will pull in on itself and cause the cut edges of the media to curl up.
UV ink
UV printing is very popular due to its capability to print on almost anything. Unlike eco-solvent ink that will partially migrate into the surface of the media, UV ink sits on the surface making it possible to print onto coated and uncoated stock, plastic, glass, wood, and media that may be difficult for eco-solvent and aqueous printers, so long as it meets the machine's media specifications eg thickness, width, and weight.
Being able to print directly onto almost anything provides many opportunities as well also delivering time-saving advantages compared to eco-solvent. For example: Imagine a corflute sign. Instead of printing with an eco-solvent onto PVC SAV then waiting for it to out-gas, trimming it, and then applying it to the corflute, UV printers (such as the VJ-1638UH MkII) can print directly to the corflute.
Customers are seeking much faster turn-around times for which UV can deliver.
Unlike eco-solvent, UV ink doesn't need to outgas. It is cured with ultraviolet light which is emitted from lamps (usually LEDs) that are mounted to the print head carriage.
Due to LED lamps running on low energy and producing minimal heat, heat-sensitive substrates to be printed to.
UV ink is cured almost instantly allowing higher ink volumes to be used creating deeper colour making it ideal for lightbox work, and because the ink sits on the surface of the substrate (porous materials will still absorb some ink), printing multiple layers and creating various textures is also possible.
UV ink naturally has a matte finish even when printing on a glossy media, however many UV printers have the option to run varnish ink which can be used to print gloss or add texture effects. White ink is also often available and can be printed either as an overlay or underlay.
Summary:
The ideal technology depends on your specific needs. Consider these factors:
Budget: Eco-solvent is generally more affordable.
Material: UV printing offers more versatility in terms of printable surfaces, however, there are many types of media made for eco-solvent.
Turnaround Time: UV printing is faster due to instant curing.
Application: Eco-solvent is generally preferred for vehicle wraps, stickers, iron-on transfers, most general signage. UV printing excels in printing directly to unqiue material, direct to rigid material, and creating textures and special effects.
Finish: UV ink typically has a matte finish, while eco-solvent can match the media's finish (glossy or matte).
Both UV printing and eco-solvent printing have their unique advantages and can be used in a variety of printing applications. By understanding the differences between these two methods, you can choose the best option for your specific needs and budget.
It is highly recommended you speak with a manufacturer to discuss your requirements.
MUTOH Australia has a range of UV printers and eco-solvent printers and is available to assist you with understanding the best option for your application.