PVC banners: sizes, grommets and how to tension them

It is always the first question, and the answer is less intuitive than you would expect: the limit is height, not length.

The machine prints up to 111.8 cm of material width. That measurement becomes the banner's height, while length runs along the roll and is effectively unlimited: a 4, 5 or 6 metre banner is no problem. If you need a banner taller than 111.8 cm, it is composed of butted panels with an overlap — excellent for backdrops, less so for a banner that flaps.

Some sizes we are asked for often, with reference prices:

• 200 × 80 cm — from € 90, the balcony or railing size
• 100 × 148 cm — € 96, portrait, good for entrances and shop windows
• 300 × 100 cm — € 140, the façade or sports-ground size

For non-standard sizes we quote by the square metre: the shape need not be rectangular, but any special cut has to be agreed beforehand.

A grommet is a metal ring reinforcing the hole: without one, PVC tears around the rope at the first serious gust.

The rule: grommets at all four corners, then around the perimeter roughly every 50 cm. On a 3-metre banner that means seven grommets along the long side, not two.

It is the part people most often economise on, and the one where they should not: a banner's hold depends on how many points share the load. With only four grommets, every gust dumps everything onto four points; with twelve, the same push divides and no single point reaches tearing.

Two special cases:

• Banner on scaffolding or mesh: close grommets, every 30-40 cm, and cable ties instead of rope.
• Banner hung only from the top, flag-style: grommets along the upper edge and a small weight at the bottom (a bar, or even a tube through a sewn pocket), otherwise it wraps around itself at the first breath of wind.

Most banners that fail do not fail because of the print: they fail because of how they were tensioned.

Tension with bungees, not rigid rope. An elastic or spring absorbs the gust and gives it back; a tightly knotted rope transfers the whole shock to the grommet, which eventually gives way and takes a piece of the material with it. This single tip extends the life of an outdoor banner more than anything else.

Do not stretch it drum-tight. A rigidly tensioned banner has no margin: any push becomes a tear. Leave a little slack — it will move, and that is fine.

Watch out for closed surfaces. A large banner on a solid gate is a sail: wind cannot pass and pushes everything. If you are leaving it for months in an exposed spot, budget for that — or consider fitting it only for the period you need.

On weight: 450 gsm is the standard and is fine for normal use. 500 gsm has more body and copes better with long exposure and windy spots. The price difference is small: if the banner will stay outdoors for months, start at 500.

As with roll-ups, 300 dpi is unnecessary: a banner is read from five, ten, twenty metres. At that distance 80-120 dpi at final size is enough, and for very large banners you can go lower still.

What really matters is text size. A practical sign-writer's rule: every centimetre of letter height reads from about 4 metres away. So:

• letters 5 cm tall → readable at ~20 metres
• letters 10 cm tall → ~40 metres
• letters 2 cm tall → ~8 metres, which is nearly useless on a façade

Hence the consequence few people accept willingly: a banner holds very little text. A name, one thing, a large phone number. If you need to explain something, a banner is the wrong medium.

One last detail: leave 3-4 cm of inner margin clear of text on every side. That is where the grommets go, and if the banner is tensioned it is the area that distorts most.