Choosing the correct weight and thickness of correx for outdoor signs and posters

roadside advertising boards
Poster sizes explained
20th August 2018

Choosing the right specification of correx for printed outdoor signs and poster boards is important to ensure their durability in all weathers. As a bit of background, Correx is actually a trade name that has become a generic term to describe corrugated or fluted plastic sheeting.

Although it’s widely thought of as a plastic version of the more common corrugated cardboard, its manufacture couldn’t be more different. As a comparison, the basic corrugated cardboard is made of 3 ‘layers’: the two face sheets with a corrugated wavy liner within, which gives it structure and thickness.

Corrugated’ plastic isn’t actually corrugated at all. Unlike corrugated cardboard, it’s one single piece of extruded plastic, with a structure consisting of two faces with internal fluted dividers.

It’s simple to make, in that a liquid plastic is forced through a metal template or ‘die’, it cools and comes out the other side as one continual length, ready for trimming into panels. Imagine a kids plasticine shape making toy, or pasta mill…and you’re somewhere near, but just on a different scale.

Standard’ correx, cortex, covex, corex or whatever you want to refer to it as traditionally comes in two thicknesses; 4mm and 6mm. Once upon a time, manufacturers kept to industry standards of thickness and weight of sheet, and sheets from different suppliers were virtually indistinguishable.

Latterly things have changed, with the tide of rising costs, and now those industry standards have disappeared as manufacturers lessen the specification of the product in a bid to save costs.

Thickness versus Weight

Correx is measured in 2 different ways, much like paper: it has a thickness described in mm’s, as well as a weight, described in ‘grams per square metre’, or gsm for short.

With regards to thickness, all manufacturers work on ‘industry tolerances’ of plus or minus 10%. What this means in reality is that if 4mm thick board is ordered, there’s every likelihood that the sheets will actually measure 3.6mm, and never 4mm. Even less likely, 10% thicker at 4.4mm!

Traditionally a 4mm thick sheet was actually 4mm thick, and was made to a weight of 700gsm. (This means that a sheet of 1m x 1m would weigh 700grams) Manufacturers are now making what they describe as a 4mm sheet in weights as low as 575gsm, whilst it’s thickness may be as low as 3.5mm on occasions.

Choosing the correct correx for the job in hand.

Screenprint & Display are experts in the production of printed correx signboards, temporary printed poster boards and the like. Working with the UK & Europe’s correx board manufacturers, we have our own specifications of correx sheet manufactured especially for our own uses. Call us today to discuss your project, and we’ll assure you of the best and most suitable material to use, to give your printed signs a long and useful life.

Email sally@screenprintanddisplay.com or call 01347 823230