I'm collecting various printing process examples for my students but I am missing rotogravure. I believe I saw it once on a beer bottle but it got thrown away and I haven't found another example so far.
How would I recognize this process and on what type of products would I be more likely to find this used?
Ideally, something that is fairly easily accessible. Postal stamps?
Rotogravure is used for very huge quantities of prints because of the cost of the cylinders that are used instead of plates; engraving the cylinders is more expensive than standards plates. They are also more resistant to large runs compared to normal offset plates that can easily get scratches or need to be prepared again after a certain quantity.
That a method often used for food packaging, corrugated boxes, mail catalogs, wallpaper, flexible packaging, postcards, etc.
According to Wikipedia:
The rotogravure printing process is the most popular printing process used in flexible-packaging manufacturing, because of its ability to print on thin film such as polyester, OPP, nylon, and PE, which come in a wide range of thicknesses, commonly 10 to 30 micrometers.
Other appreciated features include:
- printing cylinders that can last through large-volume runs without the image degrading
- good quality image reproduction
- low per-unit costs running high volume production
As for most prints, to recognize the process, you'll probably need to use a magnifier on products that are printed in big quantities and look at the pattern.
Easy to find example:
Bottle wrap from big corporation like Coca Cola like this image below
Some close up examples of Rotogravure:
Source: http://www.metropostcard.com/techniques5.html
Regarding stamps and money, you might want to investigate the "copperplate printing" process:
Gravure printing is a direct descendent of older intaglio printing (gravure and intaglio, commonly used synonymously, are different processes; all gravure printing is intaglio, yet all intaglio printing is not gravure—for example, copperplate printing, which is an intaglio process without being considered a gravure process)
Sheetfed Gravure....
A variety of intaglio plates are used for high-quality, specialty printing such as bank notes, postage stamps, money, securities, and other such documents. These can either be sheetfed or web-fed, and are more commonly known as copperplate printing. See Copperplate Printing (unfortunately, broken link)
Source: http://printwiki.org/Gravure
In this process, fine-line engravings are transferred to steel plates from which an impression is made on sheets of distinctive paper.
Source: https://en.wikipedia.org/wiki/Bureau_of_Engraving_and_Printing#Currency_production
What to use if for?
Is for long runs, hundreds of thousands, so it is (or was, I am not sure) used in newspapers, where you did not needed a superb resolution, needed fast print process, one ink, and long run. That was the main factor, durability on long runs.
But I don't know if it is very widley used today. The newspapers need a higher resolution now, want full color prints, faster preparation times, smaller runs than before...
An alternative today is flexography and rotary offset.
A plain gravure is used in shorter productions like wedings logos, embossed (or debossed) business cards, but also in a very high production line... money.
So that answers the question on why you want a gravure in the first place? You want to see and feel the emboss, or in the bills you want to feel the texture of the ink.
But in rotogravure is more difficult, becouse you did not wanted to feel the texture, but just have long durability of the matrix, so the machine did not put too much presure, so it is hard to difrerentiate from a flexography.
Probably one characteristic on rotogravure is that you could not have a big patch of ink, you need it always to have a pattern. If you have lets say a big square without a pattern, you will have a ink mess, becouse the ink needs to stay there by itself.
