This is basically a rephrase of this question from Sustainability SE. Paper manufacturer UPM claims they have paper that has the same key characteristics (as white, as thick and as usable in office equipment) as "usual" office paper but lower "grammage" (mass per square meter) and therefore (the claim continues) lower load on the environment.

One example is UPM Kymmene Yes Paper - they offer Yes Light with 70 gsm grammage and Yes Bronze copy/print with 80 gsm grammage. Looks like the two papers are very similar in everything except grammage and brightness (and 70 gsm paper even has better whiteness):

            Grammage  Thickness  Opacity  CIE Whiteness
Yes Light    70 gsm    0,105 mm    92%       165%
Yes Bronze   80 gsm    0,104 mm    93%       150%

the manufactures further says that 70 gsm paper has 10 % smaller environmental load per sheet compared to the same paper in 80 gsm.

They claim 10% lower load, but 70 gsm paper uses about 12,5% less abstract "material" compared to 80 gsm paper. Where have the 2,5% disappeared? It's "just" 2,5% when you compare 2,5% and 100%, but it's 20% difference when you compare 12,5% and 10%. If the process was explained - something like well, we make tiny enclosed pores in the sheet and that allows us to use 12,5% less fiber, but we need more energy for making those pores with compressed air so we lose those 2,5% for making pores and so the net advantage is 10%. And btw here's how we estimated that the extra energy we spend amounts to about 2,5% and not any other number. Nothing like that. The process is not detailed and there's this "10%" claim out of nowhere.

So the manufacturing process is not detailed. Do they use less fiber? How do they achieve the same thickness (do they use or add plutonium or other not so green materials)? Finally, if there exists such a brilliant technology for producing paper as usable as usual one but with less raw materials why wouldn't everyone license it?

So my question is...

Is there any independent data on how such paper is produced and how its manufacturing process is different from that of "usual" paper in environmental terms?

  • Using less material should make things greener; however, adjusting the weight (gsm) of the paper a standard process and different papers have different weights depending upon their application. I'm not sure what the skeptical claim is here?
    – rjzii
    Nov 19, 2013 at 13:52
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    @nico Mind the marketing speak, saying "very good printability and runnability" is not the same as claiming that it is exactly the same. Plus, it's not that far off the standard 74 gsm office paper.
    – rjzii
    Nov 19, 2013 at 18:46
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    My reading of their product description, however, suggests it's simply a lighter-weight paper. They don't make any magical claims that their 70 gsm paper is somehow identical to the 80 gsm paper, except that it uses 10% [sic] less material; they only claim it has a "touch and feel" of 80 gsm paper. I suspect most people couldn't tell the difference between "normal" 70gsm and 80gsm paper, by touch and feel of a single sheet.
    – Flimzy
    Nov 21, 2013 at 14:07
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    In conclusion: The only notable claim I see here is that 70gsm paper has a "10% smaller environmental load" than 80gsm paper. That's not a very interesting claim, since it only takes a little math to find the answer (and assuming gsm is a linear scale, it's really a 12.5% difference, but whatever). The interesting claim isn't actually made: that their 70 gsm paper is somehow "magical".
    – Flimzy
    Nov 21, 2013 at 14:11
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    @Flimzy We don't require questions here to be about interesting claims. If what you just said in your comment is correct, write it as an answer instead.
    – user5582
    Nov 21, 2013 at 17:16

1 Answer 1


You seem to be focusing on two specific claims made by the Yes light marketing material.:

  • touch and feel like 80 gsm

This claim is incredibly subjective, and therefore difficult to analyze objectively. It seems plausible, though, that 70gsm paper would have a "touch and feel" like that of 80gsm paper. In certain regards, all paper has a "touch and feel" like 80gsm paper, even cardstock. All paper products have a certain "touch and feel" in common. Note the claim is not that it has a "touch and feel identical" to 80gsm paper...

  • 10 % smaller environmental load per sheet compared to the same paper in 80 gsm

This claim is very easy to analyze. AS gsm is a standard measurement, and means grams per meter2, it's easy to do some simple math:

(80gsm - 70gsm) / 80gsm = 12.5%

So, Yes light has 12.5% less mass per square meter than 80gsm paper.

So the original claim, that the Yes light paper has a 10% smaller environmental load per sheet should be approximately correct. This assumes, of course, that paper weight is directly proportional to environmental load, which seems to be a reasonable enough assumption on the surface. (Perhaps examining this claim would be worthy of a separate question, if anyone doubts it).

The final claim, borrowed for your Sustainable Living post, is that the Yes light paper has the same thickness as the Yes Bronze paper:

            Grammage  Thickness  Opacity  CIE Whiteness
Yes Light    70 gsm    0,105 mm    92%       165%
Yes Bronze   80 gsm    0,104 mm    93%       150%

I don't have any of either of these papers at my disposal to measure them, but due to truth-in-advertising laws, I'm willing to put at least a small amount of faith in this claim. But more importantly, you don't seem to be questioning the claim, but rather are asking for an explanation as to how paper with less mass can match (or exceed) the thickness of another paper with more mass. Such explanations of paper manufacturing are off-topic here.

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