Back in the day (1978) I can recall working the night shift to the sound of clunk, clunk, clunk of my printing press. 
I would arrive at 5:00 PM and work 12 hours in harmony with my printing press. As I became more confident in my skills I would often run 2 presses at the same time. Operating multiple presses simultaneously requires a keen set of ears.
If you have done a good thorough set up then all you really need do is listen. There is a certain musical rhythm that printing presses play. All I would really have to do was make pulls (Check a press sheet) every 15-20 minutes. It was the pressman’s responsibility to ensure the quality of every printing order which was controlled by the human eye.
One of the principles in printing back in the day has not changed over time that is defining what makes a quality printing order. The answer to that is very simple in the eyes of a pressman, the first sheet looks the same as the last sheet. The biggest difference from yesterday’s print shop to today’s is digital control. There are digital Lithography presses, Engraving Machines, Thermography – raised printing and Letterpress. All of these printing presses are sheet fed presses and are the main topic of this blog. Printing presses and paper go hand in hand in this business. When there are problems in the pressroom it is important to quickly discover whether your problem is paper of machine related. Most of the information compiled here deals with the relationship that paper and the printing process have.
The trouble we used to experience was resolved manually 90% of the time, while today many of these problems are resolved with technology. A pressman’s mechanical and optical abilities are not really as much of a requirement. You will notice that I have put list of links at the top of the page that outline many of the day to day problems commercial printing companies faced with.
- “Pits” in Offset Plates- The printing plate is the last step in prepress. A plate is made only after the client has
approved the Proof. When plates are made they are stripped, processed and developed Or CTP (computer to plate). A plate must be flawless or the job will be flawed when printed. It doesn’t always mean that a new plate is required though. There are tools designed to help touch up plates that can otherwise be used. In most cases (not all) a plate can be repaired by contacting the subtractive area with a special pen. When repair areas are printing in 100% ink they are simple to repair, however when the pit is in one of the 4 process colors plates(CMYK) it can be a little trickier. When fine, detailed touch up is required a loupe is used to magnify the surface. This way hand etching dots is much easier.
- Lumps and Image Pick outs- Sometimes the purchasing agent tries to save a few bucks by bringing in a lower grade or converter stock. My experience has always told me to stick with the reputable brands. It is always a crap shoot when you bring unfamiliar paper types into your productive printing operation. Besides the fact that non brand paper can be a nightmare to produce on press it can also be very taxing on finishing machines such as guillotine cutters. If the material is a course fibre with higher than usual wood content it can wear out the blade on the cutter in no time. It is a good idea for the press team to be in touch with
purchasing to feedback whether a substandard material is worth the savings in the end. You will often find that the money saved on the paper ends up costing in production, plus the headaches of press people trying to pull it off. I can remember having to beat my dog on many occasions, as a result of paper that could not be massaged to run 
- Anti-Offset Spray – This is a fine white powder that is used to prevent uncured (wet) inks from staining on the back of the sheets on top. It is usually delivered by fine nozzles that are positioned at the end of the printing press just before the sheet lands in the delivery table. When a press is producing heavy ink coverage on glossy paper allot of offset powder is needed. The more ink on each sheet the higher the concentration of powder needed. This becomes even more necessary when printing orders that are covered with 100% overall ink or varnish. In the case of varnish if no offset powder is used you can end up with a solid “brick” of paper. Any press operator that has done this knows what I am talking about.
- Water interference- Water is necessary in conventional offset printing because it keeps the plate clean in the non subtractive areas (areas that don’t print). Your water solution is mixed usually with alcohol and a plate etch formula. This formula can be tweaked depending on the paper surfaces and the climate in the pressroom. It is a good idea to record formulas that work for given circumstances so they can be easily repeated. The materials that usually require different formulation are non porous printing surfaces. Here you will need a recipe for ink and water to balance perfectly. It is usually easy to see the visual impact the water interference has in the printing process in images. The images may appear water streaked and faded in certain areas. Often apprentices believe it to be a plate problem but once the plate is checked and there are no flaws it is the next logical problem and get be corrected by attaining the proper balance, usually.
With specialty papers good manufacturers will send instructions with recommended mixtures. - Fibers Contaminate Printed Image- The fibers from paper become more evident when running through a printing press. When each sheet of paper is printed with inks a tremendous amount of pressure is used. If the paper that is being printed is a textured finish, like linen or laid even more pressure is used to deliver the impression on each sheet of paper. If the paper is substandard the risk of fiber contamination is greater. When I was running presses we used to remedy this by running our thumbs on the plate surface while the machine was running. I had a few workmates that I shook hands with that had less than 5 figures. Once the fibers are removed from the plate the printed quality is noticeably better. Again, by altering the contents in your fountain solution you can compensate for paper that has high fiber release in production.
- Dust Accumulation - Dust will always build up on the blanket cylinder. The amount of build up is determined by the paper itself, the prepress cutting of the paper and overall natural dust in the air. These factors are the main contributors to dust build up on your blanket. At some point when the print blanket becomes to dust covered the press must be stopped and all blanket cylinders are manually cleaned with a rag and blanket wash. Blanket wash is a cleaner specifically made for cleaning blankets, doing wash-ups and breaking through paper substrates quickly. If dust build-up is not cleaned when necessary the over-all printing quality suffers by appearing not as crisp as it could be.
- Picking During Lithography – Picking is not as much of an issue on a single color presses. In 4 color printing a sheet of paper travels through a press and is hit by 4 different cylinders compared to one for a single color printing press. When the sheets begin to pick the pressman can hear a “picking or whipping” sound. Picking usually occurs towards the tail end of the sheets. The more solid the image is at the tail the more chance of seeing it in the image. The printed sheets will end up landing in the delivery table with a slight buckled look. That, coupled with the picking sounds are tell tail signs. You can stop up, clean the blanket and try to remove pressure on the printing press to a minimum.
In my day of printing it was always interesting, fun and challenging to know that you were producing tomorrow’s news. If I had a chance to go it again I wouldn’t change a thing. I have probably left my fingerprint in a million different places in my time on press at the same time print and litho has left a permanent fingerprint on me.
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