When we speak of Board Grades we are really speaking about the combination of papers that make up the board. The quality of paper varies tremondously as does the grammage (or weight) of the paper. In the picture to the right you can see single faced corrugated which is made up from the fluted board being laminated to a single piece of paper. This is the first step in manufacturing board.

The second step is when this single faced product is laminated to another layer of paper. This becomes Rigid Single Wall Board.

If a further layer of single faced corrugated is stuck to this it becomes Double Wall Board. This has more strength, especially when it is stacked and this would be the normal choice for boxes that are going to be pallletised.

When it comes to the choice of paper or Liner as we call it in the industry, you can choose between White or Brown in either Kraft (Almost no Recyled Content) or Brown Test as the liner with a higher recycled content is called. For the inner liner we would either use Test or Chip (A almost fully recyled paper) In practise the paper Grades and Grammages can be used in almost any combination.

And then the shape of the flute varies! As seen in the image alongside you have a number of flute sizes ranging from A-F (And some board manufacters have also introducded flute shapes of their own, meaning that we now have K and R to fit in as well!

When looking for a suitable board grade you may see something like this;

125KT BC This simply means that;

125 - The Paper is a nominal 125grams per square metre

K - The Outer Liner is Kraft

T - The Inner Liner is Test

BC - One layer is a B Flute the other a C (Double Wall Board)