This is an interesting article Kevin started to write for us at the time of his death in 2019. There’s affection and regret reading this but, as usual, pleased at finding so many interesting facts. I hope you enjoy this piece written by a wonderful friend.

A frisson of awe ran down my neck as I looked up at color on the cave wall in front of me. The image of the bison was painted 19,000 years ago, by an artist who used shades of black and ochre to showcase his skills of depth and perspective, eighteen millennia before European artists would rediscover perspective in the art of the Renaissance. Such is the power of ink and color when used with skill.

The Grotte de Font-de-Gaume is the last of the French prehistoric caves with polychrome images still open to the public—with very limited access by strict reservation. A UN Heritage site, it was discovered on December 12, 1901  by a local schoolmaster. Over 230 images are in the cave; 30 of the best are shown during the tour. Our guide, though disclaiming his skills in English, punctuated his French tour with excellent English asides to make sure we were included in the  vivid details he shared of each image. Each member of the tour seemed appropriately awed.

As I listened to our guide, an impossible thought raced through my head; what would the artist who painted these prehistoric animals think of the ease with which visual art can be created and reproduced in our modern world? 

Early inks

Until recently all inks were made from easily found natural materials. Black ink was most common (and still is).

Ink was developed about the same time in China and Egypt, around 2500 BC. India ink was actually made in China, using soot collected from oil lamps (lampblack) and water. Sometimes, animal fat was substituted for water. Iron gall ink became a standard in much of Europe for many centuries. Early records show this ink being used on papyrus in the Roman Empire, becoming a primary ink during the Middle Ages, and remaining in use well into the 20th century. Artists such as Rembrandt and Van Gogh drew with gall inks; early drafts of the Declaration of Independence were written in gall ink, as were DaVinci’s notebooks. These inks could not be erased easily, and were in great demand due to their permanence.

Illustrate what early inks were made of.
Oak gall is used to make ink.

Gutenberg’s tests showed that the ink common to the time wouldn’t work with his new invention. Water-based ink would simply run all over, so something more viscous was needed. Gutenberg set to work testing and mixing until he found a formula that worked on his presses. This ink was analyzed in the 1980s, using a cyclotron at UC Davis. Tests documented changes in ink composition as various batches were made to print Gutenberg’s Bible as it was printed over 4 years and contained a surprisingly high amount of both lead and copper. The UC Davis research played a key role in the writing of Gutenberg’s Apprentice, an historical novel by Alix Christie, describing when various books of the Bible were printed and then assembled, showing variations in substrate as well as ink, etc. Subsequent analysis done in London of six copies of the Gutenberg Bible in various countries in Europe showed that various copies were printed at different times, using a variety of ink sets of varying colors. The primary inks displayed the variations expected when mixing batches by hand. 

Modern inks

Contemporary Ink for presses comes from large scale manufacturing operations, as do inks used in inkjet printers.

One of the most fascinating areas of ink development has been the growth in various types of ink for inkjet printers. Before inkjet printers, there was a clear distinction between inks used for presses, which are made with pigments, and inks used for writing, which were made with dyes. Early inkjet printers used dye-based inks. This distinction became very important as the market for inkjet printing expanded in various directions. 

Pigments versus dyes

Dye or Pigment? It's in how the ink "sits" on the paper. Image courtesy of © DTM Print GmbH

In both pigment ink and dye ink, a colorant provides the color, and something else carries the color to the paper or other substrate on which it is used.  Pigment inks are composed of ground particles of a particular color, suspended in a carrier. Other components of pigmented ink can include humectants, which prevent ink from drying too quickly, and anti-foaming agents.  Clay is sometimes added to extend the ink as a filler. Thickening agents, wetting agents and biocides to preclude mold or other biological agents can also be included.  All of these additions can be generically referred to as stabilizing agents. 

Dye-based inks, by contrast, are composed of the colorant, which is dissolved in the carrying agent, as opposed to being suspended in the carrier (pigment inks). Water was the most common carrier for many centuries. Additives similar to those used in pigment-based inks can be part of dye-based inks. While dye-based inks continued to be used in writing pens, it’s only now,  more than five hundred years after Gutenberg first made oil-based inks for his press, we've returned to dye-based inks for use in the new technology of printing, using sprays of ink. 

This Epson P7570, and most of the large format Epson inkjet printers, use pigment-based inks that are constantly improved for durability, dry time, accuracy and consistency.

Inks for inkjet printers

The French word for a spray or spurt of liquid is giclée. Technically speaking, all inkjet printers are giclée printers. In practice, this word is used to market higher end inkjet printing, targeted at fine art markets. Fine art printing was (and is) a driver of rapid developments in inkjet printing as the technology spread into the marketplace.

Originally, inkjet printers used dye-based inks, but now, there are multiple types of inks used in inkjet printers. 

In the early days of inkjet photo printing, traditional photo company employees were fond of showing the same image printed on inkjet paper and on photo emulsion paper, taped in windows with half of each sheet covered. Very quickly, the inkjet paper exposed to sunlight faded, while the photo emulsion print stayed full of color. This gave a false sense of security about job stability to those employees. Meanwhile, inkjet printer manufacturers rose to the challenge of print longevity, and while improving aqueous inks, also released new printers using pigment-based inks. 

Much of the research devoted to ink for inkjet printers was to produce the most durable images possible.

Pigment-based inks, because they are made by grinding up colorants and suspending them in a carrier fluid, have larger molecules of colorants. While these do not sit as flat on the surface of paper as aqueous inks sit on coated inkjet substrates, they resist fading better. The best pigment-based inks are considered to be “archival”, a word connoting extended longevity. Their downsides include a higher expense to manufacture, and a need to be even more proactive about ensuring that the printer’s heads are not allowed to dry out and clog. 

So far, we’ve talked mostly about ink on paper. Time to look at inks needed for printing on other substrates. Standard papers are great for many things, but other printing surfaces are often needed, with inks appropriate to the substrates.

Dye-sublimation inks

These inks are used primarily for printing on synthetic fabrics. They are permanent, so that the printed material can be laundered without fading. Specialized dye-based inks are used to print, either directly onto fabric, or onto a special paper, in reverse.  If paper is used, the dry  transfer paper image is then sandwiched with the fabric, and run through a press at a consistent speed, temperature and pressure; fabric printed directly instead of using a transfer paper is also treated with heat and pressure. The image on the transfer paper is vaporized by the heat and pressure, transferring onto the fabric. Failure to control variables can lead to color-critical variations unacceptable to the client, and full rejection of the job, so process control is essential. This technology is in use in a variety of places, such as small, one at a time T-shirt shops, as well as high volume production operations, such as printing a whole series of Winnie the Pooh garments for Disney. 

Digital t-shirt printing heat press machine in printing production shop.

Solvent inks 

 An outdoor sign or billboard will quickly deteriorate outside if printed on paper, so other substrates are used to stand up to the challenges of direct sun, snow wind and rain. Inks designed for paper aren’t going to work on weatherproof substrates such as vinyl. Enter solvent inks. The inks are manufactured using pigments, not dyes, with carrier compounds and resin. The resin in the ink bonds the pigments in the ink to the vinyl as well as providing protection for the bonded color.

These waterproof inks and substrates can withstand fading outside from sunlight, including ultraviolet light. Surfaces such as vinyl don’t need to be coated, either before or after printing, and the range of color that can be printed is excellent. The cost to manufacture is relatively inexpensive. Downsides include the need for ventilation of the oil-based carrier compounds in the ink, the need for drying equipment to set high-speed printed inks, and the possibility of becoming allergic to these inks, which can occur for some people with repeated exposure in printing environments.  

Solvent inks can be classified as hard solvent inks or mild/Eco solvent inks. The hard inks will last longest and stand up best to the elements without requiring special coating, but require careful management of fumes through special ventilation. They also dry fast enough that they are used to print on substrates that can’t tolerate much in the way of heat. 

The mild inks are intended for use in enclosed spaces without specialized ventilation. They are slow-drying, and often require heating units to aid in efficient production times. Mild solvent inks have grown in popularity as advances in ink technology have improved pricing, color gamut and durability. Regrettably, the use of the term “Eco” is not particularly accurate, as the inks are not environmentally friendly as that term is usually understood.

UV inks

This segment of the printing market has experienced rapid growth recently. The ink contains chemicals which allow the ink to be cured with ultraviolet light exposure. After printing, the UV exposure causes the ink to dry very quickly, becoming a solid. No evaporation happens, and no solvents soak into the substrates. This is particularly desirable because of environmental and health concerns surrounding evaporated solvents.  Since the UV exposure is very short, substrates that can’t tolerate much heat can be printed using this process. The speed of this process measured from impression to fully finished print is one of its key selling points. 

Other advantages are the wide range of uncoated substrates on which these inks can be used. These inks are rugged when dry, providing sturdy, high quality prints. 

These inks are comparatively expensive, and require special add-on units to generate the UV light that will cure the ink as soon as it’s printed. These inks are not very flexible, so their use is primarily on rigid substrates, often very large sheets of metal, wood or plastic, printing using grand format devices. The ink has enough volume that prints can show a slight 3D effect, built up on the surface of the print.  

Some may think it mundane, but ink has been the lifeblood of our civilization for thousands of years. Ink gives wings to artists, shape to our writers’ words, communication to our commerce, and carries our love to those we write. It’s a far cry from the original inks made from animal suet and lamp soot, but ink has evolved to serve new needs as they appear. The forms may change, and its uses, but ink is at our heart.

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