Photo purchased from … www.depositphotos.com
The Printing Industry Exchange Blog is #12 of the best 40 digital printing blogs, as selected by FEEDSPOT.
How did they do that?
At our favorite thrift store my fiancee and I found a print of a beach scene printed on wood. The yellowish cast of the wood created an overall tone and feel of sand, and the swirls in the wood grain made it look like the wind had created dunes. The beach umbrella and empty chair (presumably the owner was in the surf) added to the overall ambiance. Don’t you wish you were there? I did.
Since I am a commercial printing nerd, my mind clicked on a few spaces, wondering how the artwork had been printed. I also thought about the options for printing on metal and glass, and even printing on irregular items like drinking glasses.
Printing on Wood
So I went to school on the subject. Apparently you can run a door, or any other large, flat piece of wood, through a flatbed inkjet printer. Such a printer differs from your inkjet printer at home in that it is huge, and it will accept “rigid media.” This is also different from the roll-fed inkjet printers used to produce full-size vinyl banners or component parts for even larger banners that are then sewn together.
UV flatbed inkjet printers are ideal for printing on wood, since UV radiation (i.e., light) cures the ink instantly on the surface of the wood.
I have also seen other wood items that have been printed and then coated with layers of flood varnish (or some other durable coating). This would be a step ahead of decoupage (laying a printed image on a box or table and then coating it with multiple layers of varnish to make the image essentially a part of the substrate). I would think printed surfboards were produced this way before the advent of digital commercial printing.
Such “print-on-wood” technology is also useful for imaging floorboards digitally. The things to keep in mind are the kind of ink you’ll be using, whether it will adhere firmly to the substrate, and how durable it will be, depending on its intended use. (For instance, printed floorboards need to be more abrasion resistant than wall panels.)
Printing on vinyl and then adhering the image to wood is a second option. And a third option would be custom screen printing, another ideal choice given the thickness of the ink.
Clearly this opens up possibilities not only for surfboards but also for all manner of interior design items.
Printing on Glass
Glass an interesting substrate. You can actually tint glass used in the exterior walls of buildings in such a manner that you can control the interior temperature to a good extent, depending on how the coloration affects the absorption or reflection of heat from the sun. Intelligent use of this capability can reduce air conditioning costs dramatically.
According to my research there are currently two main ways to image glass: custom screen printing and custom printing with ceramic glass inks. The former will not be as durable, since the screen printing inks will sit up on the surface of the glass completely. There will be no absorption into the substrate that might allow for a good bond.
On the other hand, ceramic glass printing actually makes the pigment a part of the glass, significantly increasing its durability. In this case the pigment (heat resistant enamel) is applied to the surface of the glass prior to its being tempered. The heat-based tempering process then fuses the pigment to the glass and strengthens the glass against breakage at the same time.
Granted, these options address issues of interior design and architecture, whereas it is also possible to print on drinking glasses, presumably also with these two kinds of ink. The custom screen printing ink (or digital UV ink) sits up on the surface of the glass, whereas the enamel ceramic ink would be fused to the glass.
In terms of logistics, the option of screen printing, for instance, would involve the glass’ being rolled around its center axis while the flat screen-printing apparatus above the glass allows the ink to pass through the open areas of the stencil and onto the glass.
The UV digital imaging option would involve digitally printing onto the glass, again with an ink cured by UV light, but this would also not be as durable as pigments that can tolerate the high heat of a kiln (ceramic glass inks), which would provide more durability. Presumably you can also decorate drinking glasses with printed appliques.
Understandably enough, since glass is an extremely flat, non-porous substrate, getting the ink to adhere is a challenge. In my research I learned about such products as Pyrosil and Pyrotrack, which promote adhesion. (Essentially, these adhere to the glass to strengthen the bond between the glass and the printing ink.)
Printing on Metal
I’ve seen a lot of photos printed on metal at street fairs and craft fairs. The background substrate gives a sheen to the entire print. But how do you do it? How do you print on metal?
Metal is like glass in that the substrate is exceptionally flat and also non-porous, so adhesion of the ink to the substrate is challenging.
In the past, custom screen printing and then digital inkjet printing would have been the methods of choice. In my research I learned that for the most part, digital printing is used to print photos on aluminum for display. Presumably this would be adequate, since the photo print would be hung on a wall (in contrast to something printed on floorboards or a flat metal floor). Also, presumably, using UV-cured inkjet inks would improve the durability of the inks and their ability to adhere to a non-porous surface.
That said, the new way to print on metal is via dye sublimation, which has a number of benefits.
First of all, as with dye-sub printing on polyester fabric, dye-sub printing on metal is usually done by inkjetting special sublimation inks onto a transfer sheet. This is placed against the metal substrate, and a heat press turns the solid inks directly into gas (i.e., sublimation means changing the physical state of the ink from solid directly to gas without the interim liquid state). The high heat fuses the image to the metal (as it also does with ceramic mugs and other rigid substrates–i.e., items other than fabric).
The good news is that once the image has been sublimated, it is resistant to the elements (heat and cold) as well as rub resistant and chemical resistant. The images are also resistant to UV light (i.e., exposure to sunlight), and they won’t bubble, or flake or peel off the substrate—essentially because the heat of the sublimation process has made the image part of the metal.
The one thing to keep in mind is that dye-sub printing needs a polyester base, so the metal must be coated with polyester (just like the garments used in dye-sublimation fabric printing).
The Takeaway
If you design promotional items, such as branded drinking glasses, or even glass, wood, or metal materials used for architectural structures, it would be prudent to learn about all the options you have for imaging onto these substrates.
From my research it seems that the main issues will be the adhesion of the ink to the substrate and its subsequent durability. But it also seems that you have multiple options, ranging from custom screen printing to digital printing (both inkjet and dye sublimation). Any process that fuses the image to the substrate will last a lot longer than a process that only deposits ink on the surface of the material. That said, it seems that UV digital printing is still a good (but somewhat less durable) option. In this case you at least have the ability to cure the ink instantly, which will allow it to sit up on the surface of (and adhere to) a non-porous surface like glass.
In all cases, however, it’s smart to look for skilled professionals well versed in custom printing on the substrate of choice, whether glass, wood, or metal, and to ask questions about such things as chemical resistance, peeling, flaking, and rub resistance. Make sure you vet the printer to ensure that the printed product looks as good in a few years as it did when it was delivered.