Our custom packaging specialists have been getting a lot of questions about the different printing methods, so we figured a blog post was in order.
There are 5 main printing techniques that we use in the packaging industry, each with their own advantages and disadvantages. In this post, we will focus on the following:
- Offset Lithography Printing
- Digital Printing (aka Inkjet Printing)
- Silkscreen Printing
Offset Lithography Printing
commonly known as Offset or Litho
This technique is a combination of 2 older printing methods – lithography and offset, and is an indirect printing system. It’s the most prominent technique in packaging today due to its versatility in printing and high image quality.
HOW IT WORKS:
A plate (most often made of aluminium) is engraved with the image to be printed, inked and pressed into a rubber roller to be then transferred to the printing surface which must be flat.
The ink is made of an oily substance that repels water and there is a dampening system set in place that will place water onto the surface where ink should not go. This means that the image areas of the surface will be receptive to ink, and the non-image areas will repel ink and be receptive to water.
Some presses do not use a dampening system (“dry offset” or “waterless offset”). In these cases, manufacturers use a silicone layer to repel the ink where it should not be printed.
- able to print on a variety of surfaces – paper, cardboard, plastic, corrugated material, metal and more
- high print quality
- availability of specialty coatings such as high gloss or matte soft touch
- colour gradients in graphics appear completely smooth
- high volume intake and productivity – some machines can handle up to 15,000 impressions per hour
- costly investment – need to create custom printing plates for each project
- print surface must be flat
- not feasible for short run or low volume projects
commonly known as Flexo
This technique is like a modern version of the letterpress. It gets its name from the use of a flexible relief plate in the process and is often used in the printing of food packaging.
HOW IT WORKS:
Whereas Offset is indirect, Flexography is a direct process where the rubber printing plate transfers ink directly to the printing surface.
The image is first engraved onto the plate with a laser. Then the ink is transferred from its chamber to an anilox roller where a blade removes the excess ink. After this is completed, the ink is pressed onto the printing surface, and the product is coated in the desired finishing.
Originally, flexography produced somewhat mediocre images, but with the help of digital printing, the quality has since improved.
- variety of print surfaces – corrugated paper, folding cartons, paper sacks, plastic bags, food wrappers
- Lower cost per unit compared to offset
- Lower investment costs
- print quality is still less than Offset
- colour gradients are not as smooth
- cannot produce photo quality images
Digital printing has grown rapidly within the industry in recent years. Its popularity is due to its precision and efficiency. You already have these printers in your home, office, business place and other common areas. With the availability of printers and cartridges in the market today, desktop publishing of high quality images is possible.
HOW IT WORKS:
This technique is very straightforward – the image is transferred from a device (e.g. a laptop) directly onto a variety of printing surfaces. In manufacturing, a large-format or high-volume inkjet or laser printer is used, instead of the one you may have on that desk in your study.
- lower everyday costs – no need for printing plates
- high quality of photographic and fine art print
- perfect for all business sizes
- low cost per unit for short-runs
- does not offer as many coating options (see Offset printing)
- cannot use metallic ink
- Colours may be difficult to match
- large volumes are more costly
commonly known as Gravure
Gravure is a direct and rotary technique of printing on packaging. This technique is ideal for very high volumes, such as newspapers and magazines.
HOW IT WORKS:
This process includes a rolling cylinder which is engraved with the image that has to be printed. Once completed, it is inked and pressed directly onto the print surface to transfer the image.
The rolling cylinder has different cell depths for ink. This means that deeper cells will have more ink and will be more intense in that print area, whereas a shallow cell with produce a lighter outcome.
Rotogravure printing is slowly being phased out in favour of Offset (for publication) and Flexo/Digital (for packaging).
- low cost per unit when running high volumes
- premium quality print
- cylinders last a very long time without causing any deterioration in image quality
- does not offer many coating options
- only feasible for high volumes
- high investment costs
commonly known as Screen
This type of printing is what we use exclusively to print on our reusable bags.
HOW IT WORKS:
This process uses mesh to transfer ink onto a print surface with the use of a blocking stencil to guide ink placement. Machines move a blade across the screen to fill the open mesh sections with ink. Finally, the blades reverse which causes the screen to momentarily touch the surface.
When screen printing, you can only add one colour at a time. This means that multiple screens would have to be used in sequence to produce a multicolour design.
- surface does not have to be flat
- can print on a variety of materials – PP non-woven, wood, paper, ceramics, glass, metal
- results are long-lasting – the composition of the ink contributes to the high quality allowing the design to last longer
- feasible for short-run and long-run projects
- each colour has a separate application – can be time consuming depending on the design
- need to create new screens and mesh designs for each project
Which Should I Be Using?
There are a number of factors to consider, each being unique to the client. If your biggest concern is the quality of printing, then we would suggest the following options:
- Paper Bags: Offset, Flexo
- Plastic Bags: Flexo, Screen
- Reusable Bags: Screen
- Folding Cartons: Offset, Digital, Gravure, Screen
- Corrugated Boxes: Flexo, Digital
- Rigid Boxes: Offset
- Labels & Stickers: Offset, Digital, Screen
- Pouches (Flexible): Flexo, Digital, Gravure
Other factors that can come into play when choosing a printing technique are:
- volume size
- colour accuracy
Our custom packaging specialists can guide you towards the right product, technique, volume, and more. At LeKAC, we’re not happy until you are!
Call us today for a free consultation.