Grammage of paper. The paper grades used in the liners and corrugating medium of corrugated boxes, are identified by it’s nominal weight, ie; mass of paper or board expressed in
grams/metre², or gsm.
Following are examples of the way that board grades are expressed, using the paper
grammage:
112/112-112/1 B – this indicates a very lightweight board single wall grade in B flute
200/250-140/1 C – indicates a strong grade of single wall board in C flute
The first two numbers relate to the outside liner and inside liner, then the following number after the ’–‘ relates to the corrugating medium.
175/112/175-112/2 B/C – indicates a medium strength Twin Cushion (or Double Wall) board grade in B and C flute.
The first three numbers relate to the outside, centre and inside liners, then the following numbers after the ‘-‘ relate to the B flute and C flute corrugating mediums.
Following is a list of commonly used paper grades. The grammage may vary a little from supplier to supplier, but this guide will ignore those variations:
Corrugating medium:
112 gsm Recycled – often a dual purpose medium and liner
140 gsm Recycled or semi-chem
180 gsm Recycled or semi-chem
Liner paper:
112 gsm Recycled – often a dual purpose liner and medium
130 gsm Kraft liner
150 gsm Recycled or kraft liner
200 gsm Recycled or kraft liner
230 gsm Recycled
270 gsm Kraft liner
430 gsm Kraft liner
500 gsm Kraft liner
150 W/L or Env Recycled white liner
200 W/L Recycled white liner