Materials

Coroplast aka chloroplast, corex, and other names refers to a corrugated polypropylene material which is lightweight, reasonably rigid, and low cost.

One noticeable thing about a coroplast sign is that you can see the lengthwise “flutes” which make it corrugated.  Flutes can be vertical or horizontal depending on the need for rigidity in one direction or another, or for the need to insert rod/wire in them.  Often flutes will run in the same direction as the longest side of the sign to prevent folding over in the wind or during handling.  However if you are using the coroplast with a wire sign holder (step stake) the flutes must be vertical since the step stake wires are vertical.

Typical thickness is 4mm but 6mm, 8mm, and 10mm are not too hard to find typically.  Easy to cut and grommet.  Weatherproof but can be brittle in the cold or bent in the wind.  Considered for use indoor for years unless in direct sunlight, or outdoors short-term.

We use coroplast often for real estate sign riders (top or bottom hanger), or for low-cost yardsigns utilizing step stakes.  If you have a wood backing board, applying coroplast to the front of that, while not the most professional looking close up, can be an economical way to make a sign along a highway or development property.