What Is Foam Board (Foamcore)? Uses, Thicknesses and Limits

Foam board, usually called foamcore in print shops, is a sheet of lightweight polystyrene foam sandwiched between two smooth paper facings. It is rigid enough to stand on an easel, light enough to hang with tape or adhesive strips, and smooth enough to carry a sharp print, which makes it the go-to board for indoor signs and presentation displays.

Its weak point is the same light foam: a corner dropped on the floor dents, and the paper facings do not like water or humidity. Foamcore is an indoor material.

Thicknesses we print on

Our solid signs offer foamcore in two thicknesses, both white: 3/16 in (about 5 mm), the everyday board for easel signs, posters mounted for an event and wall displays, and 3/8 in (about 10 mm), noticeably stiffer, for larger panels that must stay flat or look substantial from the side. Standard sign sizes run from 18 x 24 in up to 48 x 96 in. We print directly on the board with UV ink on our Océ Arizona flatbed, and cut custom shapes on our Colex SharpCut.

Where foamcore works, and where it does not

Foamcore is at home in conference rooms, trade-show booths, open houses, weddings, retail displays and classrooms: anywhere a sign is indoors, handled carefully and needed for days or months. It is a poor choice outdoors, in damp rooms, or where the sign will be bumped, leaned on or carried around a lot, because the surface dents and the facing can peel or warp with moisture.

Which one for your job?

Choose foamcore for light indoor signs and displays, 3/16 in for most jobs, 3/8 in for large or premium panels. Choose PVC (Sintra) when the indoor sign must survive handling, and coroplast or aluminum composite when it goes outside.

Common questions

Can foam board go outside?

Not for long. The paper facings absorb moisture and the foam dents easily, so foamcore is an indoor material. For outdoor signs, choose coroplast or aluminum composite.

What thickness of foam board should I choose?

3/16 in suits most easel and wall signs. Step up to 3/8 in for large panels, signs that must stay perfectly flat, or when the edge thickness should look substantial.

Is foamcore the same as foam board?

Yes. Foamcore, foam board and foam core board all name the same material: polystyrene foam between two paper facings.

Products where this term matters

See also in the dictionary: PVC board (Sintra), Coroplast, Aluminum composite (Dibond) · full dictionary