The process of silkscreen printing offers possibly the greatest versatility for the designer, it is flexible insomuch as it affords the opportunity to experiment with many different materials and ink systems.
A screen is made of a piece of porous and finely woven fabric (originally silk, but typically polyester or nylon since the 1940s), stretched over a rectangular wood or aluminium frame. Areas of the screen are blocked off with a non-permeable material, a negative of the image to be printed is then exposed on to said non permeable material.
The screen is placed on top of the stock, ink is placed on the top of the screen ready for a squeegee or rubber blade to be pulled down, along the screen. This process evenly pushes the ink through the open spaces of the screen onto the stock below.
Inks
Thermochromatic inks
Thermochromatic inks are heat sensitive and react when they come into contact with heat, be it the touch of a human or an hairdryer. Leuco dyes are coloured when they're at a cool temperature. Then, as heat rises, they become translucent, which lets them reveal any colours, patterns or words that may be printed on an underlying layer of ink. In other products, leuco dyes can be blended with another colour so that as temperatures change, a two-tone effect occurs. Mix blue with yellow, for example, and you have an ink that looks green at lower temperatures and yellow when heat rises. This is some basic science behind the way the inks work; there are small capsules that contain a colorant, an organic acid and a solvent. At lower temperatures the solvent remains in a solid state, keeping the colorant and acid in close proximity to each other, as a result they reflect light and create colour. As the solvent warms, the colorant and the acid separate and there's no visible colour, which in turn exposes underlying inks.
Because process is water based and consequently work only on paper based substrates, it can work on plastic but needs multiple layers of varnish to key it in
Examples
Even though it's not a new or innovative technology when used with a great concept the design can become quite innovative. For example the design below; 'The red dots are printed in heat sensitive ink, I wanted this to reflect that the 'problem' just doesn't disappear it will keep coming back unless we can continue donating and in effect touching the lives of these people.'
The image below is a business card created for somebody who produces photos and is made to look like a polaroid photograph; 'each letter or business card becomes a miniature Polaroid, snapshotting its experience with a potential client. It's delightfully analog in a world filled with more and more software induced effects. No doubt, this small analog wonder feels a step more magical than mimicking the effect on some webcam-equipped website might'
Both examples prove that when used along with a strong concept it's less of a novelty and more of an excitement, coming across innovating and something new.
Latex overprint
Latex overprint is a process predominantly used by the lottery or for the security of goods. But again when used along with a strong concept it can make the design less of a novelty and something with more meaning. For example by tying in the motion of scratching something off in with a concept something innovative and amazing can be created.
'The material on scratch cards is latex ink, to properly apply the ink to a printed material you need a nonporous surface such as a high gloss paper. Different processes take from 1-11 coats of latex ink depending upon the desired design, colours and opacity. It can be printed using three different processes; offset printing press, flexo or screen printing.' It also comes in a range of colours but the bog standard scratch card silver is the cheapest therefore the most commonly used, but if mixing your own ink up you can create what ever colour you want as long as you have it in metallic powder.
I found it really difficult to find much information on latex overprint because it's rarely used other than in commercial printing of lottery cards. Luke Obrien cofounder of Formula studio who recently graduated from our course used this process in the end of year show branding last year so I thought it would be best to go see him and find out more.
For Luke to get the job of branding it in the first place he had to pitch the idea to the board meaning he had to pitch ideas and mock ups, below is the image of his draft. He tells us because it was only a mock up he did it by himself mixing washing up liquid, binder and metallic printing powder which he then painted on to a high gloss sticky back sheet (form impermeable surface), as you can see from the picture it's quite streaky. Luke suggested screen printing the latex ink to form a much more cleaner even surface. However for the final prints they used a professional commercial printer.
The concept behind it all works hand in hand with latex overprint, it read 'this is the end', referring to the end of uni and how people feel, becoming an adult. However once the latex has been scratched off it reveals 'not' so it reads 'this is not the end' and the back reads 'this is just the beginning' I think it's a great use of the process and the human emotions.
Whereas the design below, created by Because Studio is just a novelty, something to collect and look pretty. It allows users to 'Satisfy your inner geek by choosing your favourite Star Wars galaxy then display them on the wall for all to see'
Another great use of it with concept is the third example, the scratch off cover up words within quotes that were censored by the Chinese government. There's not much information on the project but I think the whole process of revealing words that have been censored is like revealing the truth and how it stays revealed unlike returning to a solid state and hidden if the designer would have used thermochromatic ink instead. If used in the right circumstances along with a strong concept latex overprint can kind of blow minds, well for me it does because it's such a strong but simple message that is often revealed, I enjoy the whole process of user interactivity and revealing thing through touch or scratch off.
