Greaseproof Paper Weights Explained: Which gsm Do You Need?

What does gsm mean on a greaseproof quote?

Gsm is grams per square metre: the weight of a one metre square of the paper. For greaseproof the working range runs from about 30 gsm at the light end to about 60 gsm at the heavy end, and the number sits on every quote next to the size.

A higher figure means more fibre in every square centimetre. The sheet gets thicker, stiffer and a little less see-through, and a carton of it is noticeably heavier to lift onto the shelf. Thickness is measured separately in microns, but on greaseproof the two track closely enough that gsm is a fair shorthand.

What gsm does not tell you on its own is how well the paper resists grease. That depends on how hard the pulp was beaten and how dense the sheet is, which is why a well-made 35 gsm can outperform a loosely made 45 gsm.

How weight changes the feel of a wrap

Pick up a 30 gsm sheet and it drapes like tissue. It folds around a round bun easily but the corners do not hold a crease, so a wrap can spring open in the bag. At 40 gsm the sheet has a bit of body: a fold stays put and the paper rustles when you tuck it.

By 50 gsm you are into something that stands up on its own. It lines a basket without slumping and takes a sharp corner fold that looks tidy on the counter. Beyond that, at 55 to 60 gsm, the paper feels more like a lightweight wrapping stock, and it is the base for coated freezer paper.

The customer notices this too. A burger handed over in a floppy sheet feels like an afterthought. The same burger in a crisp 40 gsm wrap with a printed logo feels like it came from somewhere that cares.

Is 30 gsm greaseproof too thin for a chip shop?

For a wrapped portion of chips, usually yes. Hot chips give off steam and fat at the same time, and a 30 gsm sheet goes translucent and soft at the folds within minutes. It is fine as an open sheet in a tray or a cone where nothing is tucked, and it is the usual choice when the paper is one layer of several.

Light grades shine on the bakery side. A 30 to 35 gsm sheet separates layers of shortbread in a tin, lines a cake box or slips between slices of tray bake without adding bulk. Glassine for bakery bags sits in the same band at 30 to 40 gsm, with a smoother, glossier face.

If you want a light sheet because it costs less per sheet, ask us to quote two weights. On a typical print run the gap between 30 and 40 gsm is smaller than most buyers expect.

40 to 45 gsm: the weight most wraps settle on

This is the band that burger bars, kebab shops and sandwich counters come back to. It folds cleanly, holds a crease, resists hot fat for the length of a lunch and prints well on both kraft and white stock.

A 300 × 300 mm sheet at 40 gsm wraps a standard burger with room to tuck under. Step up to 45 gsm for a double patty with sauce, or for anything that sits in a bag for a delivery ride of twenty minutes or more.

For chip shops this band also covers the inner sheet of a two-layer wrap. The burger wrap paper sizes and weights page shows the four sizes that cover most buns.

When does 50 to 60 gsm earn its place?

Three jobs ask for the heavy end. The first is a basket or tray liner that has to lie flat under a full portion without curling at the corners or tearing when the customer lifts it. The second is a sheet that doubles as a placemat on a tray, where it must survive a knife and fork.

The third is butcher's freezer paper, which starts from a 45 to 60 gsm base and then takes a coating on one side. The weight stops the sheet splitting when a frozen joint is unwrapped at −18°C.

Heavy greaseproof costs more per sheet and takes up more shelf space, so do not order it for a wrap that is eaten in five minutes. Save it for the jobs above, where a thinner sheet would fail in front of the customer. A heavier liner for baskets and trays is the usual example.

Which weight for which job

The table gives the weights most of our trade buyers end up with. They are typical picks, not fixed rules; a quote can carry any weight in the range.

Where two jobs share a counter, pick the heavier of the two weights and run one stock. A 45 gsm sheet is a perfectly good sandwich wrap; a 35 gsm sheet is a poor basket liner.

Does a heavier sheet hold back more grease?

A little, but less than people assume. Grease hold-out comes mostly from density, and weight only helps by putting more dense fibre in the way. Going from 40 to 50 gsm buys you minutes, not hours, under a portion of fried chicken.

Where weight really helps is at the fold. A thin sheet creases hard and the fibres open slightly along the crease line, which is where the first grease shadow appears. A heavier sheet bends on a softer radius and the fibre stays closed.

So if your problem is a stain in the middle of the sheet, ask about a denser grade. If the problem is at the corners and folds, go up a weight.

Weight, print and show-through

Lighter greaseproof is more translucent, and that affects the print in three ways worth knowing before you approve a proof.

• On 30 to 35 gsm white stock a dark logo shows faintly through the back of the sheet. For a wrap that is fine; for a bag that is printed on one side it can look like a mistake.
• Kraft stock is naturally less see-through at the same weight, so one colour on 40 gsm kraft hides show-through better than the same colour on 40 gsm white.
• Heavier sheets take a touch more ink before the print looks solid, which is why a 55 gsm liner is often quoted at a slightly higher ink coverage than a 40 gsm wrap.
• A step-and-repeat pattern disguises show-through far better than a single large logo, because there is no blank area for the ghost image to sit in.

None of this is a reason to go heavy. It is a reason to look at the proof on the weight you actually ordered, which is what the free design proof is for.

How to choose a weight in five steps

If you are ordering printed greaseproof for the first time, this order of questions gets you to the right gsm without buying samples of everything.

1. Name the job: wrap, open sheet, liner, bag or interleave.
2. Say how hot and how greasy the food is when it meets the paper, and how long it sits.
3. Decide whether the sheet is handled once at the counter or carried, bagged and unwrapped later.
4. Pick kraft or white, because kraft hides show-through and lets you go a weight lighter.
5. Ask for the quote at two neighbouring weights and compare them before you approve the proof.

Samples of the stock can be asked for on the quote, and a written price comes back within one working day. Every size in the sheet and roll size chart can be cut at any weight in the range.