Silk-screen printing is one of the most popular traditional printing methods in the industry to date. It was mainly popularized by Andy Warhol in the 1960’s with the iconic duotone Marilyn Monroe prints. Before that, it was a printing technique that the Chinese came up with around 1000AD, which didn’t get introduced to the west until the 18th century.
The technique of preparing this printing method has evolved greatly since it’s first appearance and has gone from simple stencilling, dangerous chromic acid salt sensitized emulsions to the far safer light sensitive emulsions we use now.
So why would you use screen-printing?
Silk-screen printing is one of the most versatile printing methods that we use as it can be used to print a huge variety of different effects, as well as printing onto anything which is flat.
Processes that can be achieved through screen-printing include: Caviar Beading, Cracking Ink, Discharge Ink, Expanding Ink, Flocking, Foiling, Four-Colour Process, Glitter/Shimmer, Gloss, Metallic, Mirrored Silver, Nylobond, Plastisol, PVC, Suede Ink, Water-based Ink, etc.
The variety of different finishes that can be achieved through screen printing emphasizes it’s popularity in commercial printing and therefore leaves it being an important process to know about in print.
Considerations:
Ink:
In regards to the nature of screen-printing, ink needs to be a certain balance of thickness and texture to pass through the mesh screen, not instantly dry, as well as fix to the stock without bleeding.
Every kind of stock is different in thickness, texture and how it was made. This means that the ink needs to be customised to each stock or one of the previous variables might not work.
This is tailored by something called binder/medium. This medium slows the drying of acrylic colour on the screen and reduces the risk of screen blocking, making it easier to wash out. Screens kept moist, will wash out easily with soap and water. The medium can be thinned with water.
Stock:
In regards to the use of stock within screen-printing, of course, every piece of stock is different in one way or another. When screen-printing onto paper, a paper screen is needed which has a high mesh count, this prevents the ink from flowing too much through the screen and making the image bleed. Papers have a massive range of different weights and textures that will produce a different finish as well as quality. In regards to textile materials, a textile screen is needed which has a lower mesh count than the paper screen, this allows the ink to flow through it more freely which lets the material absorb the ink.
Process:
The first thing to do to begin the process of screen printing is create your artwork, this can either be rendered by hand or digitally and then laser-printed onto on a thin piece of stock. Each layer of the artwork must be in black and white, the black areas will be printed and the white areas will be masked. This is called a negative. If there are multiple colours in the finished piece of artwork, a different negative must be made for each colour in the correct size.
The next part of the process is to coat the screen with light-sensitive emulsion. This is then left until it has dried onto the screen. The screen itself is made of a wooden or metal frame with a piece of mesh stretched over it.
Once dry, the screen in placed in an exposure cabinet with the artwork placed on top. This will harden the emulsion on the screen apart from what is blacked out, this would be the artwork.
Once the screen has been exposed, the artwork can be washed out of the screen’s mesh with a hose as the emulsion has hardened everywhere apart from where it wasn’t exposed. This will leave you with a fully prepared screen. The last thing needed to do before it is ready to print is to allow it to dry again.
Once dry, the screen can be loaded into the screen-printing bed. Here is where all of the printing is done.
The ink is applied generously at the top of the screen across the width of the artwork.
The screen is then flooded by pulling the ink over the screen with the squeegee until the artwork is completely covered.
To create your registration marks, pull the acetate onto the screen bed and print your artwork onto that, then place a scrap piece of paper beneath the acetate and line it up to where you want the artwork positioned on the stock. Use masking tape to register where to put the stock on the bench.
Put your stock onto the bed aligned to the registration marks and then pull the screen down. At an angle of 45°, apply pressure and push the ink through the screen using the squeegee blade.
Lift the screen up slightly and pull the ink back over the artwork to flood the screen and then take out the printed stock and leave to dry. This process is then repeated until printing is finished.
Finishing processes:
Plastisol:
Plastisol inks are one of the most common ink types used in screen-printing onto garments. The thickness allows the colours to be vibrant even on darker materials and also has a slightly plasticised texture. The finish of this ink type can be altered with additives, which could customise it or make it softer, or it can also be made thicker with more coats. This kind of ink requires heat to cure the print, normally around 150°C.
Water-based Ink:
Water-based inks tend to penetrate the fabric more than plastisol inks. This gives the printed texture a lot more of a softer feel. Because of the nature of this ink, it’s prime use is printing darker inks onto lighter materials, it is also good for prints which cover a large area. Some water-based inks require heat for curing.
Caviar Beading:
Caviar beading is mainly used in the textile industry for making beaded patterns on the surface of a textile material/item of clothing. There are a variety of different sized beads, which would result in different effects on the printed surface. The process is the same as normal screen-printing with ink but rather than ink, you flood a specialty textile glue and then press a pile of chosen beads onto the printed area with a flat surface adding pressure to the entire design. The remaining beads are put back and the material with the glued on beads is put through a drying process, which makes the surface a more permanent fixture.
Cracking Ink:
Cracking ink is quite a new method during screen-printing. Some people are fond of the aesthetics of ink cracks on a t-shirt/item of clothing as if it has been worn a lot already; this gives the printed material a vintage/distressed look upon it. Cracking ink is essentially extra brittle plastisol ink which when pulled on before a full cure, will crack and produce this vintage effect.
Discharge Ink:
Discharge ink is used mainly as a base coat for darker materials to bleach it allowing the use of water-based inks to follow it and show up. This means rather than having to use plastisol inks to screen print darker materials, the option is available to use water-based inks giving the finished print a softer feel.
Expanding Ink:
Expanding ink, also known as puff ink originally hit it’s peak in the early 1970’s when it was first developed. This is one of the original “special effects” inks. The printed surface expands slightly during the curing process, which creates a 3D texture to prints.
Flocking:
Flocking is a process, which consists of depositing a collection of small fibre particles onto a surface. After screen printing the textile glue onto the surface of the desired printed material, this can be achieved with a flocking machine which creates a high-electric field where the fibres are given a negative charge and the material’s surface is earthed which pulls the fibres to the surface of the material, sticking to the glued area.
Foiling:
Foiling is the process of applying a shiny/mirrored surface to a material. The glue is screen printed onto the material, warmed up with a heater/dryer and then the chosen foil is placed over the top of the material shiny side up inside a heat press, the foil then adheres to the glued surface.
Four-Colour Process:
Four-colour process is a technique used to screen-print full colour photographs by using a mixture of cyan, magenta, yellow and black dots placed close together to give the illusion that each definition of the photograph is a separate ink. Using this method, only four screens are needed which reduces costs, time and set-up. Because the inks blend, they need to be translucent which compromises the vibrancy of the colour.
Glitter/Metallic:
Glitter/Metallic inks are made of a combination of the chosen ink colour and an additive of metallic flakes or glitter to create the sparkling nature of the ink. The most common form of this ink is gold and silver. The difference between glitter and metallic is the metallic ink’s particles tend to be much finer.
Gloss:
Gloss inks are used in a process which comes after the surface is printed as an overcoat, which makes the previously printed inks have a shiny finish. This can also be done by itself to give any form of stock a finish that looks very similar to a spot varnish.
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