Q. In an art store, I saw papers displayed by grades. I asked the clerk to explain the differences between each paper, and he told me that it was their weights. Can you explain the weights and grades of watercolor papers?
A. Theres a tremendous variety of surfaces and weights among papers, but each manufacturer has its own way of defining its series of papers.
For watercolor papers, you should be aware of some basic vocabulary related to surface texture. Not-pressed papers (sometimes simply called not) have been allowed to dry after manufacture without pressing under weights; their surfaces are rough and irregular. Cold-pressed papers have been pressed under cold weights during the drying process and have a somewhat irregular surface but arent as rough as not-pressed papers. Hot-pressed papers have been pressed under heated weights while drying and have a relatively smooth surface. There are other surface textures for papers, too, such as those with a plate finish (very smooth), all depending on the method of manufacture.
The weight of a paper is determined by the weight in pounds of one ream (500 sheets) of a particular paper. For instance, if a ream of 22×30 paper weighs 300 pounds, a sheet of paper in that ream is referred to as 300-lb. paper. This system can be confusing, however, because that same thickness of paper in a larger sheetsay, 29-?x4173151;would be called 555-lb. paper because thats how much a ream of the larger paper would weigh. A clearer way to designate papers of different thicknesses is to state the weight of a single sheet of paper measuring one square meter in area. This is called a papers grammage (gm/m2 or gsm), and this measurement stays consistent regardless of the weight of the ream.
To find out which paper is best for you, you may want to purchase as many different types of watercolor papers as you can, try them all and make note of the ones that are pleasing to use or fulfill a certain need.
Steve Smith is senior editor for The Artist’s Magazine.