GSM (grams per square metre): GSM is the weight of one square metre of paper or board in grams. It is the basic measure of how heavy, and roughly how strong and costly, a grade is.
In more detail
Paper is sold by grammage. A 120 GSM kraft paper weighs 120 grams per square metre. Higher GSM usually means a stiffer, stronger sheet, but strength also depends on fibre quality, so GSM alone does not define performance.
Why it matters
Price, strength, stiffness and how a sheet runs on converting machines all start from GSM. Always state a tolerance, for example 120 ± 4 GSM.
How it is measured or specified
Cut a known area from several points across the reel, weigh it and scale to one square metre. Ask how often your supplier measures it.
Questions
What is GSM?
GSM is the weight of one square metre of paper or board in grams. It is the basic measure of how heavy, and roughly how strong and costly, a grade is.
Why does GSM matter to buyers?
Price, strength, stiffness and how a sheet runs on converting machines all start from GSM. Always state a tolerance, for example 120 ± 4 GSM.
Why does GSM matter?
Price, strength, stiffness and how a sheet runs on converting machines all start from GSM. Always state a tolerance, for example 120 ± 4 GSM.
Explain GSM in more detail.
Paper is sold by grammage. A 120 GSM kraft paper weighs 120 grams per square metre. Higher GSM usually means a stiffer, stronger sheet, but strength also depends on fibre quality, so GSM alone does not define performance.
How is GSM measured or specified?
Cut a known area from several points across the reel, weigh it and scale to one square metre. Ask how often your supplier measures it.
What is Burst factor?
Burst factor is the bursting strength of paper divided by its grammage. It lets buyers compare the strength of grades of different weights.
What is Caliper?
Caliper is the thickness of a sheet of paper or board, usually in microns. It matters for stiffness and for how board runs through carton machines.
What is Kraft paper?
Kraft paper is a strong, usually brown paper used for packaging, sacks, tubes and corrugated board. Recycled kraft is made from recovered fibre.