I have been asked to try and unpick what the paper ‘weights’ and ‘grades’ are all about.
When you buy paper and card it is graded in one of two ways – by ‘weight’ – or by thickness of the sheet. It's really to give you a guide as to what you are buying.
OK - paper weights
The ‘WEIGHT’, (really the density of the paper) is expressed in terms of grams per square metre (g/m˛). The unofficial unit symbol "gsm" instead of the standard "g/m˛" is also used; very rarely you might see the symbol ‘#’.
Basically the higher the number, the heavier the paper.
There are different ‘types’ of paper :- Bond, writing, ledger / Manuscript cover / Blotting / Box cover / Cover / Bristol and tag / Tissue / Newsprint / Hanging, waxing, bag, etc. / Book, Text, Offset / Index Bristol / Paperboard (all types).
The weight of a paper type is the fixed weight of 500 sheets, measured in grams, in that paper type's basic sheet size. This way, consumers can easily compare papers of differing brands, within the same paper type. 80 g/m˛ bond paper is always lighter and thinner than 90 g/m˛ bond, no matter what its cut size. And 80 g/m˛ bond letter size and 80 g/m˛ bond legal size papers are the same weight paper having different cut size.
However, a sheet of common copy paper that has a basis weight of 80 g/m˛ does not have the same density as the same size sheet of coarse paper (like newsprint or blotting paper or tissue paper). It is important to note that the "basic sheet size" is not the same for all types of paper. So you MUST compare like with like.
It does sound a bit of a muddle – but most of the basic paper and card that you will be buying for crafting will fall into one or two types. It will probably be either cover or Bristol – and these are very similar. You might find odd differences, but you will soon be able to compare easily and develop a ‘feel’ for the weight.
Typical office printer paper is 80 g/m˛.
A nice weight for a card inner is 90 g/m2 or 100 g/m2 (Even 120g/m˛).
Card stock that you need to be able to fold easily – for albums etc 200 g/m2 – 230 g/m2
Card stock for making cards – 230 g/m2 - 270 g/m2
Framing and outer matting – 300 g/m2 +
And thickness
While paper is measured by weight, heavier card and board is measured by THICKNESS in micrometres. It is measured with a calliper and expressed mils. A mil is a thousandth of an inch (0.0254 mm)
Again, the higher the number, the heavier the paper.
VERY roughly 0.081 mm = 60 gsm
0.12 mm = 90 gsm
0.147 mm = 105 gsm
0.157 mm = 130 gsm
0.185 mm = 150 gsm
0.188 mm = 160 gsm
0.216 mm = 200 gsm
0.234 mm = 220 gsm
0.25 mm = 250 gsm
0.289 mm = 270 gsm
0.33 mm = 285 gsm
0.356 mm = 308 gsm
0.445 mm = 385 gsm
I hope that helps a bit.
Next time I will look at why art paper has different 'finishes' - it's much easier!
Design and 'how to' pages
