“Is it solvent?”
As many of our customers are aware, BIG Images produces prints on huge inkjet printers. In fact, the posters, trade show graphics, banners, and other materials offered by Wide format and Large-format printing companies depend on the same Ink Jet technology found in the office.
The Ink Jet printer is a relatively new phenomenon, replacing dot matrix only 15 to 20 years ago
[1] (although the first thermal Ink Jet printer was actually invented in 1977). Two varieties of Ink Jet exist: Thermal and Piezoelectric
[2], but ultimately, the principle behind the two are the same; a drop of ink is propelled from the ink head and onto the media at precisely the right time to produce a recognizable image at increasingly impressive speeds.
…a solvent printer is unique in that it heats up the media … leaving the ink embedded in the media!
While the mind tries to wrap around the possibility of such perfect timing, let's focus on what is important when purchasing a BIG image. Interestingly, it's not the manner in which the ink happens to arrive on the media, but the particular solution in which the ink is contained. Anyone who's ever tried to combine oil and water knows that the two just don't mix, because water is a polar molecule while oil is non-polar
[3]. Aqueous inks are dissolved in water, a polar substance while solvent inks are dissolved in, well, solvent, a non-polar substance
[4]. Paper is polar, plastic is non-polar and this is where it becomes important to the consumer.
Trying to apply a polar-based ink to a non-polar surface or vice versa achieves the same unhappy results as mixing oil and water. Aqueous inks absorb well into paper because both are polar. Likewise, solvent inks adhere well to plastic media such as vinyl banners. Aqueous inks produce beautiful results on paper but cannot stick to plastic unless the media is coated. This involves lining the vinyl material with a thin emulsion that will accept the aqueous solution, an expensive procedure which is very much reflected in the price of the rolls — and in the charge to the consumer! These lower-quality banners and vinyls can be recognized by the clay-like feeling of their surfaces. The emulsion is easily scratched, is prone to kinking, and is not overly fond of water, thus, limiting the outdoor life to 6 months.
Solvent printers, however, can print directly to uncoated plastics. Solvent printers are a relatively recent development in ink jet technology and are a much larger investment than their aqueous siblings. It is the solvent inks’ ability to print directly onto banner vinyls and other plastics that makes them so valuable. In fact, a solvent printer is unique in that it heats up the media being printed upon to allow the solvent to actually penetrate the plastic, leaving the ink embedded in the media! This means that solvent-printed vinyl medias are very scratch resistant and can be exposed to water and weather for years without harm.
This is precisely why BIG Images has invested into its solvent printer system for all its outdoor materials.
So, the next time you order a vinyl-based print, be sure to ask “Is it solvent?”
- "Inkjet Printer." Wikipedia, The Free Encyclopedia. 18 February 2007 1954 UTC
, accessed 19 February 2007.)
Thermal Ink Jets rely on a steam explosion produced by heated elements to propel an ink bubble out of the print head, while the more recently emerged Piezoelectric Ink Jet utilizes a crystal which changes shape in response to electrical excitation forcing a drop to emerge (same source as )
Electrons in a covalent bond are shared between two atoms, but if one of the atoms is more electronegative than the other, it has more affinity for the electrons. A polar compound contains atoms that are highly electronegative such as Oxygen and Nitrogen covalently bonded to less electronegative atoms such as Carbon and Hydrogen. Water is the primary example of a polar compound having two Hydrogen atoms covalently bonded to one Oxygen. The electrons spend more time in orbit around the more electronegative atom. (In water, the oxygen atom). As a result of this electron "hogging", the more electronegative atom develops a slight or partial negative charge while a partial positive charge develops around its covalent partner (the Hydrogen atoms in water). This can happen even if the molecule as a whole is neutral. Due to these partial charges, polar compounds are attracted to one another while non-polar compounds which are neutral, are repelled. Non-polar compounds have atoms whose electronegativity is closely matched. Oil is a common example, composed of long chains containing Carbon and Hydrogen. The electrons spend an equal amount time around each atom, thus each atom is neutral as is the entire molecule. These molecules are weakly attracted to one another due to Van der Waals forces and aggregate together due to their repulsion to polar molecules. (Very large molecules such as long Carbon chains with one or two polar groups can also behave as non-polar because of their overall size.) "Chemical Polarity" Wikipedia, The Free Encyclopedia. 14 February 2007 0517 UTC accessed 19 February 2007.
3 Chemists will of course argue that a solvent is any medium in which something else, i.e. the ink, is dissolved. So, technically both the water and the solvent are solvents.
