Expanding foam, also known as insulation foam, is a product that provides airtight insulation around materials, joints and components. The foam acts as a filler to seal cracks and holes around parts and fittings. These sealants form a barrier to repel moisture, insects and air from creeping into gaps.Expanding foam normally has a mousse-like consistency, which hardens via a chemical process when it comes in contact with atmospheric humidity. Once cured or hardened, the foam will not expand or shrink, being durable against damp and other weather effects.There are different packaging types available, such as spray cans and cartridges. There are also various sizes available, including 300ml, 500ml and 750ml.How to use expanding foam?Expanding foam can be applied using a foam gun, a handheld can or a spray can:Gun – Foam applicator guns or dispensing guns are widely used to apply foam and sealants. They enable easy application and can often help to control the levels of foam that are applied.Handheld – Fitted with an application nozzle, handheld expanding foam cans are easy to use and do not require additional equipment, such as a gun.Spray can – For less precise coverage, or larger areas, spray cans are an ideal method for applying expanding foam. Spray foam is a type of expanding foam which is sprayed in place using an aerosol can.PU foam (polyurethane foam) requires moisture to expand and cure. It is advised to lightly spray the area with water first. Then apply the expanding foam. Once cured, any excess can be cut or sanded off or additional foam can be added.What is expanding foam used for?Expanding foams have many uses across industry and retail, for both indoor and outdoor use. The foam sealant can be used to fill the openings and insulate around window frames, window sills and awkward gaps, and to seal pipes and hoses.Expanding foams are also applied in indoor building activities and in repair work to ceilings, walls and cavities. The foams are rot-resistant and can be used to bond and seal the rings around manholes.