Recurring spot pattern on newspaper pages

[James44]

Hello, first time poster here. Also, I am not a press worker, but a researcher.
I have found old newspaper issues with "spots" on them, the same spots, usually in a similar position, across multiple issues of the same newspaper. I call them "spots" because they are areas with the printed ink missing. The "spots" also go through to the underlying page, but to a smaller effect. For example, a paper with a spot on page 3, has a smaller version of the spot on page 4. There are several issues where these same spots appear in the same position. A friend of mine who worked in newspapers said it sounded like a damaged blanket. I think the paper was printed on a Goss.
I have no experience with presses, any ideas about this? Here are examples of 2 pages on the same piece of paper. View attachment 292417View attachment 292418
Thanks in advance!

 

[SteveSuffRIT]

Most modern newspaper press use web offset (cold-set) lithography.
The ink transfer from the plate (metal) to the blanket (rubber) then to the paper.
If the rubber blanket is damaged, sunken inward, it will not transfer ink from plate or to paper. This is often called a smash or ding.

 

[James44]

Most modern newspaper press use web offset (cold-set) lithography.
The ink transfer from the plate (metal) to the blanket (rubber) then to the paper.
If the rubber blanket is damaged, sunken inward, it will not transfer ink from plate or to paper. This is often called a smash or ding.

Thank you for your response. I'm not clear on why a blanket smash puts a mark on both sides of the paper.

 

[MacTwidget]

Thank you for your response. I'm not clear on why a blanket smash puts a mark on both sides of the paper.

This is because a newspaper press generally prints both sides of the web at the same moment. You need both blankets to firmly press against the web for each side to make an even impression. If you have a large "smash" in one blanket, the web does not have support in that area to provide a solid support for the other blanket.

 

[Richprints]

don't think of it as a mark, think of it as a lack of print. The ink is not transferring to the paper due to a low spot from smashed blankets

 

[Magnus59]

This should give you some idea of what a newspaper press blanket looks like, they are quite different to a sheetfed offset blanket
Goss Blanket change

 

[MacTwidget]

They are quite similar to sheetfed offset blankets. The only difference is the Goss Sunday 200 uses gapless blankets.

 

[Magnus59]

They are quite similar to sheetfed offset blankets. The only difference is the Goss Sunday 200 uses gapless blankets.

I was referring to the method by which they are mounted rather than the structure of the blanket material.

 

[James44]

This should give you some idea of what a newspaper press blanket looks like, they are quite different to a sheetfed offset blanket
Goss Blanket change

Thank you. Very interesting.

 

[James44]

If someone wanted to cause such a defect on a specific part of the paper, like on a particular article, could purposely damage the blanket to do that? If so, how hard would it be?

 

[Magnus59]

If someone wanted to cause such a defect on a specific part of the paper, like on a particular article, could purposely damage the blanket to do that? If so, how hard would it be?

This sounds like a tinfoil hat conspiracy theory, if you had physical access to the machine, yes, of course you could hit the blanket with a hammer, but as soon as the pressroom foreman saw it, he would stop the run and ask the operators to replace the blanket, so such sabotage would most likely be futile.

 

[James44]

This sounds like a tinfoil hat conspiracy theory, if you had physical access to the machine, yes, of course you could hit the blanket with a hammer, but as soon as the pressroom foreman saw it, he would stop the run and ask the operators to replace the blanket, so such sabotage would most likely be futile.

Well, the defect lasted about six weeks, across a few issues, only on certain days of the week. The motivations and circumstances are unknown.

Anyway, the question was not if you could damage it, but if you could do it in a specific place on a page?

 

[Magnus59]

Well, the defect lasted about six weeks, across a few issues, only on certain days of the week. The motivations and circumstances are unknown.

Anyway, the question was not if you could damage it, but if you could do it in a specific place on a page?

Once there's an image on the blanket, technically you could damage a specific area because you can see where on the blanket that section of image is being transferred.

 

[James44]

Once there's an image on the blanket, technically you could damage a specific area because you can see where on the blanket that section of image is being transferred.

Oh I see... That's very interesting.

 

[bill kahny]

Kind of like cutting the blanket to leave an "un-coated knockout" for inkjetting.