There are many different methods of printing. Two are more commonly used when designing for brochures, letetrheads etc, so I’m just going to deal with them here. Digital printing and Offset Lithography.

Digital printing

In my experience, digital printing has always been ignored by production managers I’ve worked with. This was always due to poor quality, both colour and finished surface. Digital printing didn’t, and still doesn’t, have the same quality as Litho or Flexography. But the differences are becoming less and less obvious as technology in the field increases. So, when would you use Digital?

* For short full colour print runs
* For quick turn around

Advantages

* Generally cheaper
* No plates or films to be produced, therefore costs are limited
* Quick turnaround
* Large format printing

Disadvantages

* Colour recognition can be poor
* Digital printing can often produce banding on flat colour (the same as inkjet printers)
* Expensive for large qualities
* Same price for full colour as it is for spot colour
* Limitations on printing to certain paper types/weights

How does it work?

In basic terms, digital printing is like your desktop printer, just on a bigger, more expensive scale. An operator can load up some PDF artwork, press print and away you go. You can see how turn-around can be so much quicker, the whole production process is so much quicker than traditional methods.

Offset lithography

Offset Lithography, or just ‘litho’ as it’s often referred, is perhaps the most common method of printing onto paper. Both CMYK and Spot colour can be used. CMYK is full colour printing, whereas Spot colour uses specific Pantone colours, I’ll get onto to talking more about that though. The process for litho can be daunting and drawn out, it involves many steps, which each have their own dependancies and can be expensive if screwed up. First of all, there’s the planning up, or pagination.

Printing presses use large plates to transfer the image to paper, the most common in the UK is B2 size, which is slightly larger than A2. In order to make maximum usage of the paper and plate, several items can be ‘planned up’ on one plate. This can be incredibly complex for a designer to get his/her head around, let alone do it. Luckily, most printers do this for you. When they’re doing though, just a tip - check to see if there’s extra room. Sometimes you can get freebies produced on the back of client work, such as business cards or promotional flyers.

Next up is the films. In litho printing, film is produced from your pdf or Indesign file on an imagesetter and then a metal printing plate is made from that. There needs to be a different plate produced for every colour used. So, in a CMYK job, that’s 4 plates for every full colour page. You can see how things can become expensive if there’s a typo?

Then we have proofs. Once the films are made, proofs are produced by the printers to give to the designers to check and sign-off so the plates can be produced. These proofs (cromalins or colourmatch), are colour accurate, but can be expensive. Many production managers and designers still want to see proofs made with films despite the rise of technology such as ‘Direct to Press’ printing which cuts out the production of films and goes straight to plates.

One the proofs are signed off, the plates are made and the printing begins.
When would you use Offset Lithography?

Well, I’ve used it most of the time. It’s only recently, now that digital is really starting to improve, have I started to use alternatives.
Advantages

* Superior quality
* Availability
* Cost effective for large print runs
* Wide variety of paper stocks to print on

Disadvantages

* Can be expensive
* Lead time and turn around
* Expensive to rectify mistakes

How does it work?

Offset Lithography is a bit weird. It uses the repulsion of oil and water to transfer the image to the paper. The plates are chemically treated to accept oil based inks, and repel water, on the image areas and the opposite happens with non image areas.

A plate first contacts rollers of a clean solution or water and then is inked by other rollers. The oil-based ink ‘sticks’ to the image area. The image is then transferred from the plate to a rubber blanket. The rubber blanket then transfers the image onto the paper’s surface. This is why it’s called ‘offset’, because the plate never actually touches the paper.