What is the Porosity of paper? A deep dive into the science of ink absorption

What is the porosity of paper? This may seem like a simple question, but it has a surprisingly complex answer. In this article, we will take a deep dive into the science of ink absorption and explore how porosity affects the way that ink behaves on paper. We will also discuss some of the factors that affect porosity, including weight, thickness, and composition. By understanding porosity, you can make better decisions about the type of paper you use for your printing projects!

What is the porosity of paper?

The porosity of paper is a measure of how much air can pass through the paper. This affects how well the paper absorbs ink and how fast the ink dries. A more porous paper will absorb ink more quickly, but it will also dry more quickly. This can be beneficial if you are printing on a high-speed printer, but it can also be a downside if you want your ink to dry slowly so that you can have time to fix any mistakes. A less porous paper will take longer to absorb ink, but it will also dry more slowly. This can be beneficial if you want to give yourself more time to work with the ink, but it can also be a downside if you are printing on a high-speed printer.

How to control the porosity of paper

There are several factors that affect the porosity of paper. Weight, thickness, composition, and many other parameters all affect the porosity of paper. Paper manufacturers can control porosity by adjusting these factors.

Type of fibers

Longer fibers result in stronger papers with less porosity. Common fiber types used in papermaking include wood pulp, cotton, and flax. The porosity of paper also varies depending on the materials it is made from. For example, recycled paper tends to be more porous than virgin paper.

The composition of the paper affects porosity. Papers with a higher percentage of cellulose are more porous than papers with a lower percentage of cellulose. This is because cellulose is a hydrophilic substance, which means that it absorbs water easily.

Weight of paper

The most important factor is the weight of the paper. Heavier papers and thicker papers tend to be less porous, while lighter papers and thinner papers tend to be more porous. This is because the heavier paper has more fibers per unit area, which makes it easier for the ink to penetrate the surface of the paper.

Thickness of paper

The thickness of the paper also affects porosity. Thinner papers are more porous than thicker papers. This is because thinner papers have less fiber per unit area, which makes it easier for the ink to penetrate the surface of the paper.

Manufacturing process

The porosity of paper can be controlled during the manufacturing process by adding or removing chemicals and altering the conditions under which the paper is made. An increased level of fiber refining increases the fiber bonding which reduces the porosity. Same way surface sizing, coating, calendering, etc. affect the porosity of paper.

Benefits of highly porous paper

One of the benefits of highly porous paper is that it allows for better ink absorption. This means that the ink will dry more quickly and evenly, resulting in a smoother and more consistent appearance. Additionally, highly porous paper is less likely to bleed or smudge, making it ideal for use in high-quality printing applications.

Another benefit of porosity is that it can help to prevent ink from spreading or pooling. This is because the pores in the paper act as a barrier, preventing the ink from moving around too much. This can be especially helpful when printing on glossy or coated papers, which are more prone to smudging and bleeding.

Finally, porosity can also affect the way that colors appear on paper. Highly porous paper tends to produce brighter and more vibrant colors, while low porosity paper can produce muted or duller colors. This is because the ink is able to penetrate deeper into the pores of the paper, resulting in a richer and more intense color.

Benefits of low porosity of paper

While porosity is generally considered to be a positive trait, there are some instances where a low porosity paper may be preferable. For example, if you are printing on a very thin or delicate paper, porosity can make the paper more susceptible to tearing. Additionally, porosity can also cause the paper to warp or curl if it is not properly supported.

Choosing paper for your printing projects

When choosing paper for your printing projects, porosity is one of the factors you should consider. By understanding how porosity affects the way that ink behaves on paper, you can choose the best paper for your specific application. If you need your ink to dry quickly, choose a more porous paper. If you want to give yourself more time to work with the ink, choose a less porous paper. And if you are printing on a high-speed printer, keep in mind that porosity can be both a benefit and a downside!

How do you test the porosity of paper?

To measure the porosity of paper, you need to determine how much ink is absorbed by the paper. This can be done by weighing the paper before and after it is saturated with ink. The difference in weight will give you the amount of ink that has been absorbed by the paper.

There are other ways to test porosity, but this is the most common method. TAPPI T460 method is also used to test porosity, which principle is the volume of air that passes through the test specimen.


Porosity is important because it affects the way that adhesive or ink behaves on paper. If the paper is too porous, the ink will spread out and look blotchy. If it is not porous enough, the ink will sit on top of the paper and may even run off. Do you have any questions about porosity or paper? Leave a comment below, and we will do our best to answer them!

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6 Responses to What is the Porosity of paper? A deep dive into the science of ink absorption

  1. Anura Liyanage says:

    I would like to know plant fiber based pulp package prosity
    I am making paper pulp 50% pineapple leaves fiber muxing with waste paper
    Thanking you

  2. Fabio Ortuño Ramallo says:

    Good morning, i have a problem with porosity and ink. I thing the problem is that the paper is too porous and the ink loose clarity, for example, a bright green looks like and old green, that have been there for a lot of time. But thank you for the information is very useful

    • James Johnstone says:

      Make sure the ink you use is compatible with the paper product materials. If you are using a water based ink with paper that is hydrophobic you will need to use a different ink base. Have your paper tested for porosity, or trail with other paper products with less porosity. You may need to up the dye load in your ink manufacture process.

  3. Lynne says:

    What is the proper way to identify printing paper that resists bleeding? Paper to be used with epoxy crafts.

  4. quentin says:


    how can I calculate the porosity of paper with the mass of ink emitted into the paper?


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