Laminating Pouch Size Guide

Size the pouch to the document, then pick a thickness

Two decisions, and they are independent of each other. The size has to match what is going inside. The thickness decides how the finished thing behaves in a hand.

• A3 for posters and large charts.
• A4 for letters and worksheets, and for signs. Most pouches sold anywhere are this size.
• A5 for half-page notices and menus.
• A6 for postcards and recipe cards.
• Business card and ID for badges and tags, and anything going into a wallet.

Every pouch is a few millimetres larger than the paper it is named for, which is not slack. It is the seal, and the next section is about what happens when people cut it off.

Why the pouch is bigger than the paper

That clear border all the way round is where the two layers of plastic bond to each other. Without it, they are bonded only to the paper, and paper is not something laminate sticks to.

Which produces the mistake everyone makes once: trimming right up to the paper after laminating destroys the seal. The layers separate at the cut edge, moisture gets in behind them, and within a month the thing you laminated is worse off than if you had left it alone.

If the finished item needs to be a particular size, trim the paper before it goes in. Afterwards, leave three to five millimetres of clear plastic all round and cut nowhere near the edge.

Microns, and a warning about the number on the box

Thickness decides stiffness, and stiffness decides whether the result survives being handled by thirty children.

• 75 to 80. Thin and flexible, and the cheapest per pouch. For anything that will be filed rather than handled.
• 125. The general-purpose choice. Holds its shape but still bends, which is what most classroom display work wants.
• 175 to 250. Rigid. This is the correct band for flashcards and name badges, for menus, and for anything picked up daily by children.
• Above 250. Very stiff, and worth checking your machine can take it before you buy a box.

One caution about the number itself: manufacturers do not agree on whether it means the thickness of one side or of both together, so a 250 from one brand is not always a 250 from another. If stiffness matters, read the pack rather than trusting the headline figure, and buy a small quantity of an unfamiliar brand first.

Getting a clean result

• Let the machine finish warming up. Feeding early is far and away the commonest cause of cloudy, half-sealed laminate, and it cannot be fixed afterwards.
• Sealed edge first. The folded edge leads and the open edge trails. Always.
• Centre the item so the border is even, because an off-centre sheet has a wide seal on one side and almost nothing on the other, and the thin side is where it will fail.
• Use the carrier if your machine came with one, particularly with thin pouches.
• Lay it flat to cool. A pouch bent while warm keeps the curl permanently.
• Never re-feed a finished pouch to fix a bad patch. It distorts, and it jams.

Reading the failures: cloudy means too fast or too cool, and bubbles or wrinkles mean the item shifted on the way in.

Things not to laminate

It is permanent, which makes it the wrong answer more often than people assume.

Anything you will need to write on with an ordinary pen. Dry-wipe markers work, and that is the entire point of a reusable sheet, but pencil will not mark laminate at all and permanent ink will not come off it.

Originals and documents of record. A certificate can be invalidated by being laminated. So can a passport, and so can most legal paperwork, and none of it can be undone afterwards. Laminate a copy; keep the original in a folder.

Photographs you care about, because the heat can damage the emulsion on some print types.

Anything that changes. Timetables, class lists, price lists. A laminated version that is out of date is worse than a paper one, because it looks authoritative and nobody feels able to write on it.

Before you press start

1. Find the document size and take the matching pouch. It will be a few millimetres larger, and that is correct.
2. Pick the micron band by how the finished item will be handled, not by how important it feels.
3. Check the figure is inside your laminator's rated range. Not every machine takes the thick ones.
4. Warm up, centre, sealed edge first, and lay it flat afterwards.