Gel pen
Encyclopedia : G : GE : GEL : Gel pen
Gel pens are gel inked ballpoint pens. They come in many different sizes and in a huge variety of colours. They are primarily used for thin patterns or writing, but can be used for colouring small areas in a specific colour.
Design
The general build of a gel pen is similar to that of a ballpoint pen. They have a barrel and a cap. They also have an unscrewable metal head. Most gel pens have grips, some made of rubber and some of plastic.
What distinguishes a gel pen from a ballpoint pen is, of course, the gel ink. It consists of pigment suspended in a water-based gel.[link] The pigments are typically copper phthalocyanine and iron oxides, and the gel is made up of water and biopolymers, such as Xanthan gum and tragacanth gum, as well as some types of polyacrylate thickeners. Since pigments are opaque, gel pens are available in bright colours that stand out on dark paper.
By contrast, ball-point pens use a paste ink based on a solution of a dye solute in an alcohol solvent, and fountain pens use a dye solute in a water-based solvent. India ink (based on carbon black pigment) is perhaps the ink closest to gel ink, although it is usually made with an alcohol and shellac-based solvent and is only available in one colour, black. In other words, no other kind of pen (besides "paint pens") can write on dark paper and appear bright.
Another trait of gel pens is that they resist common laboratory analysis. The American Secret Service has maintained the International Ink Library for many decades. Because manufacturers change their ink formulas slightly from year to year, thin-layer chromatography (TLC) can be used on ink from traditional pens to trace the manufacturer and date of manufacture of most inks. The pigments in gel ink do not dissolve, and therefore cannot be analyzed with TLC.
Types
There are several different types of pens. There are different sizes of nibs, ranging from 0.5 mm to 1.5mm. There are also scented varieties, like chocolate, strawberry, mint, vanilla and coffee.
Colours
The colours can range from dark browns to bright yellows. There are also several different styles of colouration:
- Normal — These include ordinary colours like black, blue, red, and green. Insoluble durable pigments are used, eg. phthalocyanine dyes, carbon black, or iron oxides.
- Metallic — These are the metallic versions of the normal colours including gold, silver and bronze. Powdered aluminium is used as the additive.
- Glittered — These are colours with glitter added to them to give a sparkly effect. Cosmetic-grade ground glass is used as the additive in Sakura-brand pens.
- Mixed — These are different colours mixed together in the ink to for an interesting effect of ink colour. These usually use pastel colours.
See also
References
- ["Just for the gel of it"], Chemical Innovation, American Chemical Society
- ["What are Gel Pens?"], WiseGEEK
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