If you’re just getting started in the vinyl sign business and have questions about those ubiquitous roadside signs on stakes (some folks call them "bandit signs"), this blog post is for you. It’s a beginners’ guide to Corrugated Plastic Sign Blanks. We’ll answer the basic questions about “cor-plastic” sign making, including how to cut it, mount it, grommet it, hang it, and even print on it. Everything you want to know about Corrugated Plastic Sign Blanks, and why they are so popular.

Cor-Plastic: What is it?
Cor Plastic Substrate
Cor Plastic substrates are durable and inexpensive.

Cor-Plastic, also known by the trade name Coroplast™ is a corrugated plastic substrate made from thin polypropylene plastic sheeting. Think of it as corrugated cardboard made from plastic. Hence the name “Cor-Plastic”. It comes in various shapes, sizes, and colors, with the most popular form being 18” x 24” white. A standard cor-plastic sign blank is 4mm thick, but thicker, more rugged versions are available. SignWarehouse offers cor-Plastic sign blanks in three sizes: 12” x 18”, the top selling 18” x 24” and 24” x 36”. Two of these three sizes have ready made companion items for displaying the sign blank. We’ll talk more about those in a moment.

Cor Plastic Close Up Showing Flutes
Cor plastic close up showing flutes, which always run parallel to the short side.

What makes these lightweight plastic signs so popular? They’re vinyl friendly, easy to use, versatile, and very affordable. Cor-plastic is the ideal substrate for short term outdoor vinyl graphics. Its smooth surface makes for quick and permanent adhesion by just about any adhesive backed vinyl. The flutes (the open channels inside the corrugation) make it easy to mount on vertical stakes for quick and easy insertion in any relatively soft unpaved surface. For this reason the finished package is often referred to as a “yard sign”. By the way, the flutes are always parallel to the short side. This means that when the sign is mounted on a stake, it would be in "landscape" mode. For use on hard surfaces like sidewalks, cor-plastic signs can be displayed in small portable A-frames. For indoor displays, these nifty light weight signs can be easily hung with grommets or new hangers that fit inside the flutes. So cor-plastic blanks can be used in lots of different commercial and retail spaces from roadsides to restaurants. And finally, they’re very economical. At less than a dollar a piece, corrugated plastic sign blanks are the industry’s least expensive vinyl substrate. So if you’re going to offer low cost retail signs, cor-plastic is a must have in your shop’s inventory. Once you’ve got it, how do you mount, cut, or hang it?

Stakes and Flutes
Cor Plastic Yard Sign on H Stake
Digitally printed cor-plastic yard sign on metal "H" stake.

 The most common application for cor-plastic signs is the roadside or yard sign, mounted on sign stakes, also known as ‘step stakes’. The most common question about this type of display is the orientation of the flutes. On 18” x 24” sheets, the flutes are perpendicular to the 24” side of the sign blank. In other words, they are situated so that, when you mount the sign on the stakes, your sign will be in a “landscape” orientation, 18” tall and 24” wide. Mounting is a simple matter of aligning the flutes with the tops of the two vertical stakes so that the stakes can penetrate the flutes, and gently pushing them together so that the stakes go in evenly. To plant your newly mounted sign, place the lower stakes in the ground and push. You can apply pressure with your size twelves on the lower bar, but do so gently. Placing your foot in the middle of the bar may bend it. To reduce the risk of deforming the crossbar, place your foot at the edges where the crossbar is welded to the stakes. Switch from left to right to step the stakes into the ground evenly. If you have particularly tough ground or very high winds, you may need a thicker, heavier gauge stake like the Heavy Duty Cor-plastic holders.

A-Frames, Hooks and Grommets
Red cut vinyl on yellow cor-plastic mounted in A-frame stand.
As noted above, cor-plastic signs can also be used as street signs on hard surfaces using A-Frames or other displays. A-Frames are designed to display two sign blanks; front and back. Most of these are lightweight portable plastic items with channels into which your decorated signs can be easily inserted. These come in sizes configured for 18” x 24” and 24” x 36” sign blanks. The downside to being portable is that they can be ‘ported’ from place to place by heavy gusts of wind. For a more robust way to display your cor-plastic signs, opt for the popular new Wind Sign. Wind Signs have upper and lower channels into which you can slide the top and bottom of a 24” x 36” sign blank. They have heavy bases into which sand or water can be poured to increase weight and wind resistance. And they have wheels for easy movement from place to place. But don’t limit yourself to using cor-plastic as ground or floor based signage. These light weight substrates can also be used for hanging displays using hooks or grommets. Two clever new products have been designed to facilitate the use of cor-plastic for indoor signs. The Twist N Hook and Pick N Hook, introduced to the market in late summer 2011, can be fitted snugly into the flutes of a sheet of corrugated plastic. Each has a hole through which wire can be run to hang signs from lowered ceilings and other architectural structures. And finally, for vertical displays, corrugated plastic blanks can be turned into vertical hanging displays using good old fashioned grommets. Because of its relative softness, a 4mm cor-plastic sign blank can easily be pierced by standard #2 grommets using a grommet setter.
Cutting & Printing Corrugated Plastic Signs

As you become more proficient selling cor-plastic signs, you may get orders for non-standard sizes or large volume signs. Non standard signs are a particular challenge. Because it’s so thin and soft, one would think cutting a corrugated plastic sign blank to a smaller size would be a simple matter of whipping out your safety ruler and Olfa knife. Not so. It’s almost impossible to get a straight edge if you have to cut parallel to the flutes. You’ll need some cutting tools designed to handle this hurdle. We have a couple of handy options: the Coro-Claw and the Coro-Claw X. What about cutting across the flutes? If you are doing just a few signs, then you can use your trusty OFLA knife with a good straight edge. If you are doing quite a number of blanks, you can use use a vibrating multi tool. Used with a straight edge it can produce a pretty clean cut.

What about large volume signs? If you get an order for 1,000 signs with two to three colors -- a distinct possibility in an election year—you will quickly discover that weeding all that vinyl is no fun. That’s when you need to consider picking up a screen printer designed for sign stock. If you’re not ready for high volume orders yet, don’t worry. Just take advantage of the unique properties of cor-plastic for easy, high margin signs. It’s the most affordable and versatile sign substrate ever invented and works especially well with vinyl graphics. Corrugated plastic and vinyl go together like peanut butter and jelly, Batman and Robin, dollars and cents.