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Paper Thickness and Weights - Don’t Get It Twisted August 13, 2015 21:56

Paper comes in a multitude of thicknesses, weights, feel, and finishes. All of these attributes and combinations have different purposes. With so many variables, all of this can often be confusing, even for people who have been in the industry for some time. Even the most O of the Gs have trouble differentiating sometimes. So chill, and let me lay it down:


Pound

Probably the most common way of measuring paper is weight (or by pound); often you’ll see a package of paper saying 24# text or 80# cover. This is generally used to understand paper used in small format printing applications as it refers to the weight of a an uncut ream of paper, or 500 sheets. So a 24# text would represent the weight of 500 sheets. It is important to note that the basic sheet size is not the same for the different types of paper (e.g. bond, book, text, cover). Confused? Don’t worry, you really only need to know the common ones. There are actually two other main features of paper which are also often misunderstood: thickness and weight.


Mil

Most roll media, such as the paper used in large format printers, is measured in thickness by it’s caliper, which is indicated in “mils.” Often confused for millimeters, a “mil” is actually an imperial measurement and refers to one one thousandth of an inch. So, for instance, Poster Perfect’s Premium Matte Poster Paper has a caliper of 10 mil, meaning it is 10/1000’s (or 1/100th) of an inch. Paper thickness is a crucial determinant when choosing the purpose and function of your print. Generally, the thicker the paper, the less likely it’ll get damaged, and the more long term applicable it will be.


GSM

Paper weight is measured in a number of ways. For our purposes, we’ll take a look at the grams per square meter, or GSM of a paper. This is simple enough: the GSM is simply the weight in grams, of a one by one square meter piece of any given media.

Though paper weight often has a correlation to paper thickness - the thicker the paper, the higher the GSM - it is not always so direct. A good example would be to compare the weight and thickness of Poster Perfect’s Satin Photographic paper (8mil, 198 GSM) and our Premium Matte Poster Paper (10mil, 200 GSM). These two papers are a whole 2 mils different in thickness, or 20%, while they are only two grams different in their paper weight, about a 1% difference. The reason for this has to do with a number of factors. Density, material composition, and surface texture are all reasons why a very thick paper may have a lower GSM than that of a thicker paper. Our Satin Photographic paper is very densely compressed and so has little air makeup contributing to its volume. Furthermore, the printable surface has very little texture, resulting in a very smooth lustre finish. We typically use mils and GSM to describe our paper because it gives the best overall detail about the paper we use.


Summing It Up

pound: weight per 500 sheets (one ream of paper) of a standard sheet size based on grade (bond, book, text, cover)
mils: measures thickness (or caliper) of a substrate; 1 mil = 1/1000 of an inch
GSM: grams per square meter, measures weight in grams per 1 by 1 square meter


Paper thickness and weight are good things to be familiar with, since knowing what you need will eliminate the guesswork and ultimately save you time and money. It’s important to be informed so you can get the right kind of print for your project, one time for your mind. Be sure to ask your printer if you have any questions!