Weight Just A Minute! What’s the deal with this paper?
I don’t know about everyone else, but more than once I’ve confused myself trying to determine the differences in paper weights. The paper weight on one package says it is 60 lb paper, but yet it feels much lighter than another package of paper that states it is also 60 lb weight. What’s the deal? Unfortunately, the Constitution does not guarantee that all paper is created equal – so let’s try to figure this out.
Understanding paper weights is best accomplished by first acknowledging that, yes, it’s confusing. The U.S. unit of measuring paper in pounds (lb) is more complex, or perhaps perplexing, than the metric system, which measures paper weight in grams per square meter (gsm). Pound weights vary as to the type of paper it is – or how it’s categorized. For example: text stock (including bond stock, book stock, writing stock), or card/cover stock. What can be even more confusing is that paper weights within the categories can differ. For example, a bond paper weight of 24 lbs is the same as a text paper weight of 60 lbs. Rattled yet? An eye opener for me was when I learned that the basis weights for each paper type is based on a fixed weight of 500 sheets of that paper’s standard sheet size. Ah! Since not all standard paper sizes are the same, as a result the basis weights are likely to vary as well. Now we are getting somewhere. Above we used the example of bond weight and text weight, so let’s compare a standard sheet size for those two papers: a bond sheet size is 17” x 22”, but a text sheet size is 25” x 38”.
So how can we best get an apples to apples comparison when looking at different papers? I mentioned earlier the metric system’s use of gsm (grams per square meter). Let’s call this the “equalizer”. No matter what paper type you are comparing, gsm makes all things equal: the higher the gsm, the heavier the paper weight. Using the example of bond vs. text weight, let’s see what the gsm weight is: 24 lb bond is 89 gsm, and 60 lb text is (drum roll please…) also 89 gsm.
Putting it into practice, I can offer up the following suggestions: First, when trying to understand the lb. weight of paper, determine what paper type is being defined (bond, text, cover, etc.). Second, look for the “equalizer”, the gsm weight. If you can compare paper weights based on gsm, then you have a straight forward comparison unclouded by other variables. Third, whenever possible, feel the paper to compare the weights! All the math in the world is no substitute for a good ole’ fashioned touch test. It’s not scientific, but can be effective. When all else fails, there are several online tools available that can help – both conversion charts and tables.
Other attributes that affect the overall properties of paper are caliper (thickness), and sheffield (texture)…but I’ll leave the science of that to those more knowledgeable than myself – like the engineers at our Southworth paper mill.