Introduction
What Is Paperboard
Paperboard is essentially thick paper. It is usually at least 0.0012inches thick and can be thicker.
How Is Paperboard Made?
The paperboard manufacturing process follows the continuous commercial paper-making process using a variation of the Fourdrinier machine. dryers are arranged in groups called sections. Paper dryers are typically arranged in groups called sections The gaps between sections are called draws.
Pulp
Wood chips are processed chemically and mechanically to render the fibers used to make paper. The fibers are mixed with water, additional fillers, and additives to make pulp.
Paperboard pulp is made primarily from wood chips and recycled paperboard.
The pulp is stored in the headbox.
The headbox agitates the pulp so the fibers are well mixed. It also dispenses the right amount of pulp onto the forming section through an opening called the slice.
Forming Section
The pulp, which is more than 99.5% liquid, feeds onto a rotating mesh that stretches between two large rollers. The flat area is called the drainage table.
Several rollers support the drainage table. Suction boxes draw the water out of the pulp.
The moving mesh and the suction boxes orient the fibers in the pulp, so they begin to form paper.
When the paper web reaches the end of the drainage table, it is about 25% paper fibers.
The paper leaves the forming section and moves to the press section.
Press Section
The paper web moves off of the drainage table mesh onto a felt belt in the press section.
The press section removes most of the remaining water by mechanical pressing. Pairs of rollers squeeze the paper web against a water-absorbing felt.
The space between rollers is called the nip. It is essential to the entire paper-making process. You may see references to the nip as you read about paper and its manufacture.
Initially, the felt belts were wool. Today, they are synthetic water-absorbing fibers specifically woven to maximize water absorption.
Presses can either use a single felt or a double felt. Single felt presses make one side smoother than the other. Double felt presses are used in the first stage of paperboard production because it makes both sides rough.
As the felt rotates, it goes through its drying station.
By the time the paper leaves the press section, it is about 35% paper fibers.
The paper leaves the press section and moves to the dryer section.
Dryer Section
The paper sheet now enters the dryer section, which finishes removing water from the paper.
The dryer section uses another method to dry paper. The forming section squeezes the paper web against felts, which absorb the moisture. Unlike the forming section, the dryer section uses evaporation to remove water.
The paper web passes over a series of steam-heated cylinders. The heated cylinders make the water evaporate very quickly.
To improve evaporation further, felt belts hold the sheet against the heated drums. Dryer felts have a very open weave made of coarse thread that lets the moisture quickly pass through them.
Also, the dryer is usually enclosed to hold heat and improve the drying rate.
Paper shrinks as it dries. So the dryer section is often made up of several different groups of dryers.
The paper leaves the dryer section and moves to the calendar section.
Calender Section
The last step for the paper is the calender section which puts the final surface finish on the paper.
This section uses multiple pairs of steel drums to compress the paper reducing its thickness.
When it completes this section, the paperboard is cut to its final size and stacked for packaging.
What Is Chipboard
Chipboard is the name Americans use for paperboard made from 100% recycled paper. It comes in a variety of densities and thicknesses. It is usually brown like kraft paper.
Crafters use chipboard for scrapbooking, bookmaking, paper modeling, rubber stamping, laser cutting, and putz houses.
What is Greyboard
Greyboard is the name used primarily in the UK and Europe for paperboard made from 100% recycled paper. It is usually gray because recycled newspapers are a significant part of the pulp.
People also refer to it as strawboard because, in the past, cereal straw was the principal part of the pulp.
Paperboard Sizes
If this is your first time looking for some paperboard, selecting a size may seem a bit confusing.
Fortunately, paper sizing works the same for all paper products. Two characteristics of paper, its thickness which is called the caliper, and weight are used to size all paper.
You are probably used to thinking about paper only in terms of its weight. For example, when you buy paper for your computer’s printer you go looking for a specific paperweight. You never really give any thought to the paper’s caliper(thickness).
Because it is so thick, the paperboard’s caliper(thickness) is more important than its weight. While you rarely see the paperboard weight listed whenever you go shopping you can’t ignore it.
You could find two paperboards of the same caliper(thickness) but one weighs more than the other. The one that weighs more has pressed more fibers into the same caliper, so it is denser. This usually means it is also stiffer.
Most paperboard is mediumweight. But you can find heavyweight and lightweight versions of the same caliper paperboard. Depending on the kind of paper crafting you are doing, paperboard weight may be important to you.
How Does The US Size Paperboard
Caliper
Caliper is measured in points.
One point is equal to 1/10000 of an inch or 0.0001inch.
So 25 point paper is 0.0025 inches thick.
Weight
The basis weight of paper is the weight of a basis ream.
For paperboard, a basis ream is 1000 basis pages.
The dimensions of a paperboard basis page are 12inches x 12 inches or one square foot.
Thus the basis weight of paperboard is the weight of 1000 square feet of paperboard.
How Do ISO Countries Size Paperboard
Caliper
Caliper is measured in microns. A micron is 1/1000 of a millimeter. So 1000 microns equal 1 mm.
The symbol for a micron is µ – the Greek letter mu. You will often hear people talk about Mics. A Mic is one Miron.
Unlined chipboard comes in calipers from 300 Mics (0.3mm) to 5000 Mics (5mm).
Weight
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