Spray foam

Spray foam is a very specialised packing material, often required for use in shipping valuable fragile items. Engineered packaging principles are designed to protect sculptures, vases, large fossils, lamp bases, busts, computers, furniture, chandeliers and other objects of unusual shape. By virtue of the liquid foam expanding by up to 280 times the volume of its liquid state, it efficiently protects almost any size, form and weight. Instapak, a product made by Sealed Air, is a common trademark for this sort of packaging.

The custom fit of the molds, top and bottom, securely and uniformly cushions the object. There are many types of alternative materials that can be used to handle more specific needs.

"Spray foam" is also an informal term used to refer to various plastic foam materials that are used in building construction to provide thermal insulation and minimize air infiltration. Polyurethane and polyisocyanurate are two types of foam used in this application.

Another type of use quite familiar in South East Asian countries is applying the pu or pur foam by spraying it against the bottom of roof tiles under high pressure with a spray gun. A hard but flexible layer of rigid foam is then created and seals all the tiles to each other and to the steel structure.

This spraying method, especially very popular in Thailand, is used not only against heavy leaks but helps also as insulation against the enormous heat the roofs constantly face.

This tropic heat actually is the cause that the steel structure, which most roofs in that part of the world are built on, expands and contracts all the time. By doing so, the sun-battered steel structure causes the roof tiles to dislodge and slowly creates small openings between the roof tiles, through which rain water can run into, creating leaks that can cause much damage to plastered ceilings and electric wiring.