Inkjet Paper: Peeling Back the Layers
There is a temptation to look at the price of a box of inkjet paper and be a little indignant at the price. It’s just paper after all? Isn’t it? Well, no, it’s not just paper. There is a lot of technology and chemistry that goes into making good quality inkjet papers. Manufacturers have to ensure the printed image will be stable over time, that the ink adheres properly, that the paper can absorb the correct amount of ink to achieve a good colour gamut, that the paper has the correct weight and stiffness for the purpose, and a host of other factors. Papers go through an exhaustive research, development and testing process.
This blog will give you a brief introduction as to how the different types of inkjet paper are made. Once you understand the differences it may help you choose the correct paper for your print.
Images © Paul Gallagher, Abi Symons, Martina Cross, Paul Hassell,
Andrea Campiche & Nigel Harniman
Photo papers mimic the look of analog photographic prints and are glossy or semi-glossy in appearance. The actual paper is sandwiched between layers of polymers and coatings that give the paper its gloss, curl resistance and stiffness. The top micro-porous ink layer allows dye ink through almost instantly to an amorphous silica or precipitated calcium carbonate coating below whilst pigment inks tend to be held in the pores themselves. This rapid absorbency means they can typically take more ink than a matte paper and deliver a larger colour gamut.
The pores in the ink receiving layer are as small as 20nm, and they have to be to absorb the picoliter droplets of ink coming from the inkhead. The total ink receiving surface area of an A4 sheet of photo paper can be as large as a tennis court. The speed of absorbency guarantees a sharp dot shape rather than a slow spread of the dot that you would see on uncoated plain paper. The polyvinyl alcohol in the ink-absorbing layer also has small electrical charge that helps it bind to the oppositely charged ink. The polymer layers make photo papers water and touch resistant. Metallic inkjet papers have an additional metallic layer that gives them that metal-like look.
Fibre-based (Baryta) inkjet papers have a layer of barium sulphate, a clay like mineral, coating on top of the base paper. This gives the paper a high level of reflectivity and whiteness, while maintaining a traditional look and feel. On top of the barium sulphate there is an additional coating to absorb and bind to the ink. The base of a baryta paper can be either cotton or wood-pulp based
Fine Art Papers
The base paper in fine art papers are typically made more traditionally and often contain large percentages of cotton and other natural fibres. The papers can often be given a texture by being passed through special rollers. All inkjet fine art papers have a top ink receiving polymer coating. Otherwise the ink would just soak into the base paper. The difference in the coatings and layers of fine art papers is the main factor that requires them to use matte black ink rather than photo black ink. The chemistry of the black ink changes in each case to make it suitable for particular paper types.