What keeps pigment ink on paper

Started Jul 21, 2019 | Discussions
Alexey Senior Member • Posts: 1,223
What keeps pigment ink on paper

i understand that with dye ink, the dissolved color particles are so small that they travel deep into and under the coating of photopaper.  But what keep pigment ink on paper?  What prevents it from falling off the surface once dry, especially with matte papers?  Does some amount actually fall/rub off with time as photos are handled?  Or does pigment somehow become one with paper?

mike earussi Veteran Member • Posts: 8,757
Re: What keeps pigment ink on paper

All inkjet paper has a coating on its surfaces called a microporous coating. This keeps the pigment in place.

https://www.freedompaper.com/large-format-inkjet-media-coatings

https://www.photopaperdirect.com/blog/?p=118

OP Alexey Senior Member • Posts: 1,223
Re: What keeps pigment ink on paper

Does that mean that if I print on paper that is not microporous, (say, regular printer paper),  more of the pigment will fall off once dry?  If I handle the pictures once in a while, is it likely that considerable amount of the dye will be worn off or fall off the surface in, say 100 years?

mike earussi Veteran Member • Posts: 8,757
Re: What keeps pigment ink on paper

Alexey wrote:

Does that mean that if I print on paper that is not microporous, (say, regular printer paper), more of the pigment will fall off once dry? If I handle the pictures once in a while, is it likely that considerable amount of the dye will be worn off or fall off the surface in, say 100 years?

What do you mean by regular printer paper? All inkjet paper today has the microporous coating on it. If it's not made for inkjet printing then it has no coating and the print will look washed out, dull and unsharp and the ink may rub off (but it won't just fall off).

technoid Senior Member • Posts: 2,276
Re: What keeps pigment ink on paper

mike earussi wrote:

Alexey wrote:

Does that mean that if I print on paper that is not microporous, (say, regular printer paper), more of the pigment will fall off once dry? If I handle the pictures once in a while, is it likely that considerable amount of the dye will be worn off or fall off the surface in, say 100 years?

What do you mean by regular printer paper? All inkjet paper today has the microporous coating on it. If it's not made for inkjet printing then it has no coating and the print will look washed out, dull and unsharp and the ink may rub off (but it won't just fall off).

Depends on the printer. Generally, printing on regular paper doesn't dry as quickly and may smudge for several minutes after printing. Ink is a mixture of water and a glycol. They both soak into inkjet paper fairly quickly. Nearly instantly. You can even run water over it right after printing and it won't run.  Not so much on regular paper and it can take some minutes to dry depending on the printer. But regular paper makes pretty awful prints with really bad DMax and washed out colors. If you want to print on regular paper get a dye printer.

NAwlins Contrarian Veteran Member • Posts: 5,303
Paul Roark says inks have binders.

[W]hat keep pigment ink on paper? What prevents it from falling off the surface once dry, especially with matte papers?

I know that I don't know, but I know that Paul Roark is an expert with inkjet printing, at least / especially B&W. He reports that inks need binders to adhere to glossy / coated inkjet papers, but not to matte papers. To quote one of his papers:

Because there is no binder in this generic base, inksets make with is are very clog-free. Binders needed for glossy inks are a type of glue that is a major factor in inkjet clogging.

Significantly, the Canon and HP pigments have a coating that is compatible with the generic base with no binders because the HP and Canon pigments have their own coating technology that binds the particles to the glossy papers.

See http://www.paulroark.com/BW-Info/Ink%20Mixing%20Generally.pdf.

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