Coroplast

Coroplast is used in the making of plastic signs. In much of the SPAD world, coroplast is usually shortened to "coro".

Coro is the plastic equivalent of corrugated cardboard. It consists of two parallel plastic sheets with vertical spars between them. The channels created by these spars are termed 'flutes'. When working with coro, always ensure that you are thinking about the direction in which the flutes travel.

Coro usually comes in two varieties of thickness.

4mm
2mm

The 4mm seems to be more prevalent than the 2mm.

Cutting Coroplast

Coro can be cut using a sharp knife such as a new bladed box cutter. It is strongly recommended that a guide be used to ensure that the blade does not deviate from any desired straight line. Making a few scores with the blade rather than a single deep cut seems to give the best results and best accuracy.

Cutting in the same direction as the flutes is easiest, cutting against the direction of the flutes is also not that difficult. Cutting with the flutes can be easily done with a hand held flute knife such as a Coro-Claw. The most challenging direction is one that is neither parallel or perpendicular to the flutes but rather at an angle. The texture of the cut keeps changing. Slow and steady seems to offer the best results.

Flashing Coroplast

In order to glue one piece of Coro to another, CA glue may be used. Unfortunately, it is not enough just to apply some glue to the parts to be bonded. By nature, the plastic used for making Coro does not bond well unless its surface is first "activated". A common technique for achieving this is called 'flashing'. This involves passing a flame over the surface for just a moment, being careful not to melt the surface. A hand-held torch seems to work well for this task and can be purchased for under $15 from your local hardware store. Test your technique on a scrap piece first. Water should not form droplets, but a thin film on properly activated Coro.

Pinning Coroplast

The flutes of Coroplast can be attached to make a column or free standing sign by using a Coro Pin. The pin acts as a huge bobby pin and goes in the flutes of two sides of Coroplast to attach them.

Suppliers

Regal Plastics - Retail supplier in TX, OK and LA.

References

Coroplast home page - The makers of Coroplast.