Technical difference between matte and glossy papers

[OmerYair]

Hello,

Even though I'm aware of the apparent differences between the many types of papers, I have no idea what is technically different between them. What makes a glossy paper glossy? What makes it matte? I know from other printing forms that gloss can be achieved by adding a layer on top of the paper base that holds the printing material while matte paper is made of a single layer that is used both as base and as the printing material - is it the same with pigment papers?
If matte paper can absorb more ink as stated by many forum posts, why can't it absorb the black glossy ink (in Epson's case)?
What is Canon's glossy ink? Is it a black pigment similar to Epson's or is it an opaque shinny layer?

Where can I find more info on the subject?

[OmerYair]

If it interest anyone here, this is Carsten Sürig's answer (Digital line products manager at Hahnemühle):

"Glossy and matt papers are different because of their coating. The paper base might be the same for some glossy and matt papers. There are different types of coatings, such as matt, glossy and semi-glossy coatings which are applied to the paper base. Inkjet coatings are absorbing the ink and prevent it from getting into the paper. If there would not be an inkjet coating on top of the paper, the paper fibres would absorb the ink and would spread it across the paper surface (this would almost look like as if you would apply watercolour with a paint brush in one spot on an uncoated paper)."

[Ernst Dinkla]

What makes a glossy paper glossy? What makes it matte? I know from other printing forms that gloss can be achieved by adding a layer on top of the paper base that holds the printing material while matte paper is made of a single layer that is used both as base and as the printing material - is it the same with pigment papers?
If matte paper can absorb more ink as stated by many forum posts, why can't it absorb the black glossy ink (in Epson's case)?
What is Canon's glossy ink? Is it a black pigment similar to Epson's or is it an opaque shinny layer?

Most inkjet coatings have more than one layer applied to the paper base, 2 - 3 or more is not uncommon. For both matte and gloss papers. That is just the inkjet coating, the base material can already have different layers like in RC papers there are polyethylene layers at the front and back of the paper base. Starting from pure paper base there usually is a barrier that prevents the ink media to penetrate the paper base, on top of that a layer that absorbs the ink media and on top of that a layer that fixes the pigment but allows the ink media to go through to the second layer. Hahnemühle Photorag for example has 3 layers applied by Sihl. Gloss can be the result of a satinizing with calendars the top layer of finely ground absorption powders (micro ceramic etc) and/or an additional coating with gelatine or PVA. The last is usually for dye inks.

There is no problem with the absorption of black glossy pigment inks by matte papers but that will not deliver a gloss black on matte papers and the maximum density is lower than possible with matte black pigment ink. The last has more pigment particles that are also larger than the particles in black gloss pigment ink. To improve on that some printer models also squirt larger droplets of matte black pigment ink than they do with gloss black pigment ink (HP models and that method is more often used in CAD printer models). The finer black pigment particles are ground and the more homogene they are the less opaque they become. The gloss black has to penetrate the inkjet coating better to create a glossy surface and gets its high Dmax there mainly by the gloss, an optical effect. The matte pigment black has to rely on its opaqueness to reduce the white reflection of the paper, the bigger pigment particles will not penetrate a gloss coating and reduce gloss too by their size.

Talking about pigment inks there is not that much difference between Canon, HP and Epson black inks that matter for your subject. There is a polymer encapsulation on all the pigment particles to enhance the bond to the coating and reduce gloss differences if printed on gloss papers. The encapsulation can improve fade resistance and is sometimes colored to neutralise the usually warm carbon pigment.



met vriendelijke groeten, Ernst
Shareware too:
330+ paper white spectral plots:
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm

[Johnny_Boy]

... Hahnemühle Photorag for example has 3 layers applied by Sihl. ...

What is the significance of the 3 layers on Hahnemuhle Photorag? Are all photorag papers like this, or only Hahnemuhle? Are 3 layers BETTER than 1 or 2 layers?

[OmerYair]

Thanks for replay Ernst!

If I understand correctly, the higher DMAX of glossy surface papers is caused since more light is reflected in one direction instead of spreading evenly to all directions? (The less light reaches the viewer is translated into deeper black?)
I don't know if it is related but it can explain why matte papers exhibit better highlights gradation when compared to glossy papers under the same lighting conditions.

[Geraldo Garcia]

That is right.

A matte surface reflects light diffusely while glossy surfaces also produces specular reflections. More glossy, more specular and less diffuse reflection.
It is possible to have a matte and a glossy paper that, when printed with black ink, have the same level of absorption and reflectance of light, but usually the black on the glossy paper will look darker than the black on the matte paper because of the way the light reflects on the surfaces.

Let´s say that the black printed on both papers absorbs 90% of the light and reflects 10% (just to ease the math), on the matte paper we will have 10% of diffuse reflection and on the glossy paper, lets say, 8% of specular and 2% of diffuse. If you put both papers on a wall, at the eye level, the light coming from the ceiling will likely hit the paper from an angle about 30º to 45º. The diffuse reflection on the matte paper will send some of the reflected light towards your eyes, lets say half of it, so the black area on that matte paper sends 5% of the light back towards your eye. On the glossy paper the specular reflection will bounce at the same angle towards the floor, not hitting your eyes that will only see half of the diffuse reflection, 1% on this example. That makes the black on the glossy paper looks much darker than the black on the matte paper, even if both reflects the same amount of the light. You will only see specular reflection on the glossy paper if you have a light source at the opposite angle to your eyes, then you see a glare.

As our brain/eye combination compensates the white point easily, but not the black point, a interesting thing happens: the perceived contrast on matte papers varies inversely to the amount of light hitting the surface. On a dark room you have a lot of contrast, on a bright room not so much. On a glossy paper the amount of light has less influence, but the angle of incidence of the light can reduce the perceived contrast due to glare (specular reflections of lights or bright walls).

I hope that helps and forgive-me if the text is not well written, I am not used to give this explanation in English.

Best regards.
 

  

[Ernst Dinkla]

What is the significance of the 3 layers on Hahnemuhle Photorag? Are all photorag papers like this, or only Hahnemuhle? Are 3 layers BETTER than 1 or 2 layers?

With Photorag the first coating applied is to improve the bond between the paper base and the following coatings -a primer-, then a coating for absorbing the ink medium/water is applied followed by a coating to reduce bleeding = keep detail, the one that arrests the pigment particles. When asked about some canvas qualities and different pricing it was explained to me that cheaper qualities had only 2 coatings. Which gave a lower Dmax and less gamut. I expect similar policies with other manufacturers.

For sheets you may see an extra coating applied at the back to keep the paper flat in changing humidity. Some manufacturers find it as easy to give both sides the same coating which has the same result but also make the paper printable on both sides.


met vriendelijke groeten, Ernst
Try: http://groups.yahoo.com/group/Wide_Inkjet_Printers/