Papers and boards: Stock forms, sizes and quantity calculations

Welcome to Papers and Boards: Stock Forms and Calculations

Ever wondered why the paper in your printer is always the same size, or why a cereal box feels much thicker than a birthday card? In the world of Design and Technology, we use stock forms and standard sizes to make sure materials are easy to buy, transport, and use. In these notes, we will look at how paper and board are sold and how you can calculate exactly how much you need for a project.

1. What are Stock Forms?

A stock form is the standard shape and size that a material is produced in by a factory. Instead of making every single piece of paper a custom size (which would be very expensive!), manufacturers stick to a set of rules. This makes materials cheaper and ensures they fit into things like printers and folders.

Common Stock Forms for Paper

Paper is usually sold in sheets or rolls. The papers you need to know for your exam are:
• Copier paper: Standard paper used for printing and writing.
• Cartridge paper: Thicker, high-quality paper often used for drawing.
• Tracing paper: Translucent paper that allows you to see through it to copy designs.
• Bond paper: High-quality durable writing paper.
• Heat transfer printing paper: Also known as sublimation paper, used to transfer designs onto other surfaces using heat.

Common Stock Forms for Board

Boards are thicker than paper and are used for packaging and displays. Key types include:
• Folding boxboard: Layers of printable surfaces, used for most retail packaging like cereal boxes.
• Corrugated board: Has a "fluted" inner layer for strength; used for heavy-duty shipping boxes.
• Solid white board: High-quality bleached board used for luxury packaging.
• Foil-lined board: Laminated with a thin layer of foil to keep heat or moisture in (like takeaway containers).
• Packaging laminate (e.g., Tetra Pak): A complex material made of paperboard, polyethylene, and aluminium foil used for liquids like milk or juice.

Key Takeaway: Buying materials in stock forms keeps costs down and ensures consistency across the industry.

2. Standard Sizes: The "A" Series

You are probably familiar with A4 paper, but the whole "A" system is very clever. It is based on a simple ratio. If you fold a piece of paper in half perfectly, it becomes the next size down.

• A0 is the largest size in this series and has an area of exactly \(1\text{m}^2\).
• A1 is half the size of A0.
• A2 is half the size of A1.
• A3 is half the size of A2.
• A4 is half the size of A3... and so on!

Memory Trick: The larger the number, the smaller the piece of paper. An A5 sheet is much smaller than an A1 sheet!

Did you know? If you put two A4 sheets side-by-side, they make exactly one A3 sheet. This relationship makes it easy for designers to scale their work up or down.

3. Measuring Thickness and Weight

We don't usually measure paper by its thickness in millimetres. Instead, we use GSM.

Paper Weight (GSM)

GSM stands for Grams per Square Metre. It tells you how much a single square metre of that paper would weigh.
• Standard printer paper is usually about \(80\) to \(100\) gsm.
• Anything over \(200\) gsm is generally considered to be board rather than paper.

Board Thickness (Microns)

While board can be measured in gsm, it is also often measured in microns (\(\mu\text{m}\)).
• \(1000 \text{ microns} = 1\text{mm}\).
• A typical business card might be around \(350 \text{ microns}\) thick.

Quick Review: Paper is usually described by weight (gsm), while board is often described by thickness (microns).

4. Quantity Calculations

In your exam, you might be asked to calculate how much material you need for a specific product. This involves a bit of maths, but don't worry—just take it step-by-step.

Calculating Area

To find the area of a rectangular sheet, use the formula:
\(Area = length \times width\)

Example: If a designer needs a piece of board that is \(0.5\text{m}\) long and \(0.4\text{m}\) wide:
\(Area = 0.5 \times 0.4 = 0.2\text{m}^2\)

Calculating Wastage

When you cut a shape out of a square sheet of paper, the bits you throw away are called waste. Designers try to minimize waste to save money and the environment. This is often done by tessellating (fitting shapes closely together).

To find the Percentage Waste, use this formula:
\(\text{Waste \%} = \frac{\text{Total Material} - \text{Used Material}}{\text{Total Material}} \times 100\)

Costing Calculations

If you know the price of one sheet, you can find the total cost of a production run.
\(Total Cost = Number of Sheets \times Price per Sheet\)

Common Mistake to Avoid: Always check your units! If the price is given per square metre but your sheet is measured in millimetres, you must convert them first so they match.

5. Summary and Tips for the Exam

• Standardisation: Stock forms make materials cheaper and easier to use globally.
• The A-Series: Remember that A4 is half of A3. If you need \(4\) pieces of A4, you can cut them from \(1\) piece of A2.
• Material Choice: Use Corrugated board for strength (shipping) and Foil-lined board for insulation (food).
• Maths: Always show your workings in calculation questions. Even if your final answer is wrong, you can get marks for using the correct formula!

Final Tip: When calculating how many items you can cut from a sheet, always round down to the nearest whole number. You can't make half a cereal box!