Auction catalog weight - it's not lumber doing that
- its dirt ( Well, OK, clay)

Ever ask yourself: Wait a minute, books are made out of paper and paper is made out of wood. So why is this coin auction catalog heavier than a similar-sized plank of wood? The reason those beautiful auction catalogs are so darn heavy I learned from my old field of advertising which involved a lot of coordination with printers: Clay coated paper.

NOTE: I am a new NBS member, and over the last two months I have read every E-Sylum of the last 15 years and seen no mention of catalog paper weight - thus here you go!

This advertising device I dealt with during more than 25 years as an advertising agency owner. Those wonderful glossy catalogs with those razor-sharp images are printed on the nicest paper stock for photos which is called coated stock. Coated with what? The coating is white clay. So you could say that is a type of dirt, or mud or pottery being added to wood pulp and doubling the weight of the basic paper's ground wood.

If photographs are just sort-of important, the book can be printed on a nice uncoated stock. But when many millions of dollars worth of coins and banknotes are being illustrated, only razor-sharp, vibrant reproduction of four-color images will do.

Coated papers have a smooth clay coating applied over the groundwood base paper. The base paper is made first, then put through a bath of clay coating while running on a machine, followed by calender rollers smoothing out the coating and adding as much as half the weight of the paper.

Coated papers are categorized into grades by their brightness and gloss levels, but they all add a lot of weight because of the clay coating. The coating is finished to a high gloss, or it may be matte, or dull. The most expensive of the coated papers are the heaviest - and those coin auction companies do not cut corners.