Myths about inkjet ink - Part 1

By learning about the properties and the formulations of inkjet inks, we arm ourselves with the knowledge to better understand cartridge problems that we encounter. In Part 1 of Myths about inkjet inks we look at a overview of the make up of inkjet inks.

Distilled or RO Water
Pure water in most inkjet inks is the largest component of the ink. Pure water is exactly neutral at a PH of 7.00 and it is important to remember that all components of the ink are water soluble or in the case of pigments are a suspension.  

Glycol or other Humectant
Humectants are extremely important in a inkjet ink. Without humectants the ink would clog or dry in the inkjet cartridge nozzles in an alarmingly short period of time. Remember, most modern day inkjet nozzles are about 10-20 micron in diameter. So it's extremely important for the ink to contain the correct percentage of humectant. With inkjet inks its a trade off - too much humectant can result in  long drying times. Depending on the humectant used, too much may also result in the ink being too thick (viscous).

Colorant
The pigment or dyes in the ink produce the color of the ink. It's important to remember that the quality of the dye or pigment can be the main determing factor in the quality of the ink from the customers perspective. Colorants are the main cost involved with inkjet inks, the cost of colorants cannot be hidden. A better quality colorant is more stable, more reliable, produces better colours with better light and smudge resistance and with pigments smaller and more advanced pigment dispersions. Remember that very low cost inks which are on the market cannot contain a higher grade colorant as the colorant in many cases is more expensive than what these inks sell for.

PH Buffer
A Ph Buffer effectively sets the ink at a correct PH. For example most inks are in the PH range of 7 - 9.5 (Alkaline). The PH of the ink in our case must be compatible with any existing ink remaining in the cartridge and also compatibility with the cartridge and the printers purge system. The PH of the ink must not vary too much as components like the colorant will only stay in suspension or solution at a certain PH.
So by adding various solutions into the cartridge that are not compatible with the ink - like tap water which contains chlorine etc and an unknown PH can cause issues with the ink which of course can affect printing or the cartridge reliability. It's also important to remember that the PH of tap water can be between 6 and 8 generally depending on where you live - pure distilled water is PH 7.00 and contains no additional chemicals.

So its best to clean inkjet cartridges with a dedicated inkjet cleaning solution or at the least pure water and not tap water.

Surfactants
Surfactants are commonly used all around us - most cleaning products contain surfactants. You may not know what a surfactant is but in inks it lowers the surface tension of the ink - which is critical in the ink drying time on the paper and the spread of the ink drop. Surface tension of different inks vary between cartridges and whether the ink is designed for a black text type ink or a colour or photo ink.

Co-Solvent
Co-solvents are used to change the viscosity of the ink or help a colorant or other component becoming part of the solution or suspension.

Biocide
Biocides are added in less 1% of the formulation - they are designed to prevent microbes and bacteria from growing in the ink and changing its properties which will effect the PH, viscosity, surface tension and colour in many cases. This is extremely rare and I have only ever seen ink been affected this way once in over 10 years.

Other agents
There are quite a few other agents which can be added to an inkjet ink for various reasons. UV inhibitors can be added to some dye colorants to help UV/fade resistance. Water soluble binders or resins can be added in very small quantaties to aid in reducing smudging in a ink. There are many many more additives that are used for various purposes. You wont be surprised to hear that many of these unqiue additives like many things in our industry are all patented.

SENSIENT INKS

We promote Sensient inks (a $billion corporation) because they are an ink centric company that employ all of the above factors in their manufacturing processes. They only use premium products and state of the art technology and practices which is why they are the world leader in the production of cartridge specific inkjet inks.

In part 2 we look further into the properties of ink and how it all works in a ink cartridge.