In this description, "Corrugated" is used as shorthand for corrugated cardboard. The free CORTEC guide has more information on where to find corrugated, and how to effectively use it in theatre work.
A 4'x8' sheet of corrugated, as used in the scene shop, is composed of one or more linerboard walls sandwiching one or more corrugated flutes. The flutes, consisting of a series of cardboard arches, are glued to and supported in place by the side walls, creating a remarkably strong structure. Corrugated has become a sophisticated, hi-tech product, with strength requirements designed for modern needs, such as stacking boxes to great heights and surviving the rigors of long distance shipping. When laid flat on a hard floor, it is strong enough to be walked on with flat shoes without denting.
To satisfy its customers, many combinations of corrugated boards have been developed. The basic types are single face, single wall, double wall, and triple wall. there are several sizes of flutes, with more than one size frequently being used in the multiple wall configurations. For flats, the double wall 4'x8' sheet with a size B flute combined with an E flute on the front surface works well.
Corrugated always has a front and a back. The front wall linerboard is somewhat heavier material, creating a smooth surface. On the back of the sheet the corrugations are slightly visible, especially when lit at a low angle. This makes laying out folding and cutting lines easy, as the flutes provide a reliable 90 degree, parallel grid to draw & measure by.
Corrugated commonly comes in a Kraft color finish and a White color finish.
For stage use, corrugated MUST BE FIRE RESISTANT for safety, and to meet local fire code regulations. For instructions on how to effectively treat corrugated, please consult the guide.