Trapping, Plating, Trimming, and Printing: Let’s Talk Offset Printing.

Design, Printing

I want to talk about something that people in nearly every business will run across from time to time but might know nothing about, Offset Printing.

Anytime anyone is looking to print a large amount of one thing, from event coordinators printing invitations to corporate communicators making annual reports, it pays to know some details on how the deed gets done. Think of it think way, if you know nothing about fixing cars and your mechanic says you need new spark plugs and wants to charge you $500 to do it, you might not question the cost and never know your being taxed for your lack of know-how. This article will help demystify some of the dark arts of offset printing and might give you a leg up if you have to haggle print costs. 

Nuts & Bolts: What is Offset Printing?

99% of all print jobs are going to be done one of two ways: Digital or Offset. Both use CMYK colors to make all of the images. You are probably familiar with digital printing without even knowing it. Copy machines and office printers are classified as “Digital” printers. Digital printers use a very similar process, but use rollers or drums to get the ink on the page. Having Office Depot or Staples print off 50 band fliers, that’s gonna fall under digital. 
Offset printing uses metal plates that act as screens and apply the ink to the paper, one metal plate for each color. They are placed in order on a press then the paper is ran through on a spool, inked with each color and then cut to fit the finished size. The set up to run one print job takes considerably more time as opposed to digital. Think about the jobs you send to your network printer: a picture of your niece, a menu to that Chinese take-out place (the good one with the dumplings, not that other one), a meme that you are going to post on your cubical wall. Now imagine that each one of those would require four metal plates, lined up perfectly to make the printout, and then inked up. Digital printers can do that in a minute vs Offset would take hours to get one dialed in just right. 

When It’s Worth It: What is the magic number?

So if Digital printers are so much more versatile, why do things the hard way? Digital printers internally set up each job individually, even if it’s the same page being printed each time, they have ways to speed it up a bit and preferences saved, but it is still doing one piece of paper at a time. Offset is optimized to do one thing well, and that is to make one thing over and over, fast. What is the magic number? 2,000 copies. That is when the tables turn, and Offset starts to be a better value. The trick is, the more you print the better that value gets per piece because at that point you are nearly only paying for the paper you are printing on. An Offset press can also run much quicker than a digital printer once the job is running. 

Jargon: Print Speak.

Here are some terms you might hear getting thrown around when ordering a large offset print job. While most of them might not apply to every job, it will help you haggle if you know what you might not need.

Sheet Fed and Web. Sheet Fed means that each piece of paper is printed one at a time, pulling each sheet like your copy machine or home printer does. This is typically used for smaller jobs and they print what they need and no more. Web press is a much larger press that can print lots of jobs at once from one huge roll of paper that isn’t in sheets, the jobs get cut out of the sheet later. Some things to note, web press sometimes do “gang runs” of several smaller jobs at once. Imagine this as a puzzle where the press techs are trying to fit the most amount of dinner plates on a table. The end process means plating a bunch of odd shaped print jobs in a group and running the press to meet the quantity of the largest job on the press. This could be a bonus for you if you are hoping for any overages on your print job. I have had gang run jobs coming back with double what I asked for with no increase in the quoted price. 

Plating. This is the term you are most likely to hear from a printer because it is where the cost usually comes from. Plating is making the individual four color plates that will put the color on the paper. Think of each plate as a stamp that puts down the color. There will be four of them for the average CMYK job and if there is a change to what you want to be printed at the last minute that means they will have to remake all four plate. TIP! You are printing an invitation to an event and your printer already has made the plate and is printing later today when you get a call that one of your speakers can’t make it. Crap. The good news is If you are making a minor type change to text that is set up as black ink only (which it should be anyway) and if the text is in white space (i.e. doesn’t run over any pictures or other printed color), then they will only need to change one plate, the black one. 

Trapping. Sometimes called “Knock Out” as well. This one is more inside baseball than the rest, I know plenty of designers who don’t know what this means. Trapping is when you make sure the things on the page that you are printing don’t overlap in the final print set up. That large orange circle that acts as a background is a vital design element to the invitation, but so is the photo and text that go over the top of it. Trapping means that when they print, each object only takes up the space that is shown in the final product. 

Bleed. A bleed is any time you print beyond the dimensions of the final product and then trim it back to not have a border of white space on a final product. Bleeds cost more because it adds several additional steps to a print job and a lot of paper waste as well. 

Trimming. Pretty self-explanatory but can be costly so watch out for unnecessary trimming. If you have a print job with no-bleeds and it is running on a sheet fed press, then you shouldn’t need to trim at all. 

Color Bars. These are blocks of color that help the printers monitor ink levels to make sure that levels are not running low. They can check the dots to see if there are changes in the tone. 

Crop Marks. Lines that mark the edge of a document, most commonly used for print jobs with bleeds, but if the job is running on a web press they will need them regardless of bleed or not. 

Registration. The lining up of all of the four colors. A registration mark (looks a bit like a bullseye) is printed with all four colors, along with bars of each individual color, on jobs with a bleed. If the registration gets out of line then the registration mark will start to look blurry, with a halo of the color that is moving slightly. Jobs that come out looking blurry had poor registration. 

Binding. If you are printing anything that folds, from a multi-page book to a card, then you will have to pay for binding. Even a simple fold over card would require a score and a fold, both of those steps take time and precision to set up. 

Score. When the printer makes a mark or crease so that when the final fold happens the paper does so nice and clean. 

Web Break: Means the web press is down while they fix something, usually a paper feed or a roller somewhere started making the worlds biggest spitball out of your job. As in “We had a web break and the press is down for an hour while we clean up.”

Burn a Plate. This means making a plate, not destroying a plate. As in “the client decided they like cornflower blue better than the orange background so we have to burn all new plates.” 

Plate Wear Out. Even the metal plates will wear out after hundreds of thousands of prints, during those very long runs the printer will have to make back up plates. 

Work and Turn. When printing a two-sided job the printer will sometimes set up the press to double the size of the paper, printing the front on the right side and the back on the left for the front. Once the job is done they flip the paper and do the same on the back, knocking out two pieces at a time.

4 over 4, 4 over 1, 1 over 1, etc. These are color terms. If you are printing a postcard that has a full-color image on the front, but only black text on the back, that is a 4 over 1 (as in there are four colors on the front and one color on the back). A flier that has full-color images on the front and back would be a 4 over 4 (four colors on the front and four colors on the back). 

Matte, Satin, Gloss. Just like paints, printing can have finishes. Gloss would be your shiny, high-sheen finish, Satin would have a slight sheen, and Matte is flat with no sheen. I usually recommend Satin as it evens out the texture and discourages smudging.