[[image:Expanding foam & tape tube extension 4661-3.jpg|right|200px]]
==Uses=* Fills gaps between sheets of rigid [[insulation]], to make the whole layer draughtproof & insulating * Fitting windows * Fills holes where [[Plumbing|pipes]] go through walls ** [[cement]] mortar is a more traditional option ** Foam accomodates small amounts of movement * Insulates awkward to reach small spaces
==Types=Open cell versus closed cell, aka half pound & 2 pound foams * Closed cell has more resistance to passage of moisture, insulates more, and is stronger & denser
Some foams expand a lot, low expansion foam only expands a little.
Some come in a can with delivery mechanism, some are intended for use with a separate better quality foam gun. After use the gun must be cleaned out with solvent while the foam's still liquid.
Basic foams are flammable, and can produce toxic smoke in a [[fire]]. Fire rated foam gives fire resistance time.
==Gotchas=Things can go very wrong with expanding foam... [http:// www.diyfaq.org.uk/humour.html#foam canoe story].
The high level of expansion can catch people out, resulting in spilt wet foam & damage.
Some foams generate very high forces as they expand /after/ solidifying. Misused as cavity [[insulation]] it can bring down masonry walls with its expansive force. Don't fill enclosed spaces with expanding foam, it needs expansion space.
The stickiness of the wet foam can be a problem, resulting in it getting spread a lot unintentionally. Pay attention to stray wet foam blobs. Put a dustsheet or newspaper down.
Set foam is too weak to give much support to solid [[filler]] applied over it. Where this will be done, allow enough room for a good depth of filler, and preferably reinforce the bulk of the filler with any of: * plastic fibres * metal mesh * added [[Adhesive|PVA]] or cement * or use [[sand]] & cement rather than filler for the bulk
==Tips=Damping the material its sprayed onto can help it set faster.
If a longer delivery tube is needed and nothing's to hand, an extension can be made with [[Tapes|tape]], as shown in the pic above.
Protect the cured foam from daylight, UV degrades it rapidly.
Set foam has a mess of a finish, but is easily trimmed with a [[Knives| knife]].
=ìonomising=If money's tight: * Use cheaper fillers where insulation isn't needed, such as [[cement]] mortar. * Cut sheet [[insulation]] to fit, rather than guesstimating. When possible hold it in position and draw round with a pen to see where to cut. Don't assume room corners are square, they're often not. * Poke insulation offcuts or scrap expanded polystyrene into any big gaps so less expanding foam's needed. Its easiest to inject some foam then press the pieces in. * Sometimes gravity can be a pain, with wet foam applications repeatedly falling out of position, wasting foam. Apply [[Tapes|parcel tape]] to partially cover the gap to help it stay in place while wet, then apply the foam behind it.
==Cleaning & Removing=Wet foam is sticky, drips a lot, and causes troubles.
===Skin==Nothing removes set foam from skin other than determined scratching and peeling. If you ever wondered what waxing feels like, this is your chance to find out. Trouble is it takes lots of small tear-offs, and a lot of scratching, so expect the skin to look red for several days. Its not too evil, but avoidance is only sensible. Get all you can off before it sets! Lightweight gloves are recommended.
===Clothes==Its tempting to scrape the wet foam off, but don't. This pushes the remaining film of foam into the cloth, making it impossible to remove later. The result is ruined clothes. Remove the clothing and leave the wet foam to set untouched. The whole lot should peel off later leaving a clean result.
==Êrpet==Same principle applies to [[carpet]], prevent anyone treading on it and let it set. That way you minimise penetration into the pile, and can get the maximum amount of removal in the end.
===Hard Surfaces==Wipe the wet foam off, or let set and peel off.
==Storage=Shelf life is shortish. Once the can is opened, further storage is optimistic, but sometimes succeeds, especially with separate gun type foams.
==Disposal=Left over foam can make fake turds for the kids. Don't move the nozzle while depositing, keep it completely still, and dump the foam onto polythene or newspaper. The can can go in the bin.
[[Category:Adhesives]] [[Category:Cleaning]] [[Category:Fixings]] [[Category:Insulation]] [[Category:Materials]] [[Category:Plastics]] [[Category:Windows]]