The thickness of paper stock measured in thousandths of an inch or the number of pages per inch.
Bulk refers to the thickness of paper; thicker papers have greater bulk. Bulk affects how the paper feels and performs well, so its influence must be recognized.
There are two forms of bulk: apparent bulk and true bulk. Apparent bulk refers to the thickness of paper when dry, while true bulk measures thickness when wet.
Bulk is important as it determines how the paper feels; thicker paper stiffens up more. Furthermore, bulk also affects its performance: thicker papers resist creasing and folding more efficiently than thinner versions.
Bulk can be measured using various techniques. One such approach involves using the caliper, which measures stack thickness in microns or thousandths of an inch.
Weighting the paper stack provides another method for measuring bulk, known as its basis weight and expressed as pounds per ream (500 sheets).
Bulk is paramount because it determines how the paper feels and performs, with thicker papers having greater bulk.
Bulk should always be an important consideration when choosing paper thickness. Bulkier papers can be more difficult to fold and crease, taking up more space in your office or storage facility. On the other hand, thicker papers tend to be more durable, withstanding wear and tear better. If you need durable paper for use in scrapbooks or photo albums requiring constant abuse (i.e., scrapbooks/photo albums), bulkier would likely be your best bet. However, if folding/ creasing needs are easier or storage space is limited, thinner papers might be best.