Spray Foam Cans

No. These are gun-grade refill cans: foam only, designed to screw onto a spray foam applicator gun. They are not straw cans.

If you don't have a gun, a complete spray foam kit includes the gun, cleaner and safety gear with the cans. If you're only missing the tools, the IxirPro Starter Kit adds a gun, cleaner and safety gear without foam.

A straw can sprays through a disposable plastic tube. It's fine for a few small gaps, but once you open it, you generally need to use it all within a short time before the valve seals up.

A gun-grade can has a threaded valve that locks onto an applicator gun. The gun lets you control the flow precisely, from a pencil-thin bead to a wide fill, and it keeps a partly used can sealed for weeks. You also waste less foam, which is why insulation work is done with gun-grade cans.

• IxirPro 25oz: about 20 sq ft at 1 inch. A good all-round refill.
• Magic Chems 25.4oz: a similar yield, about 20 sq ft at 1 inch.
• IxirPro 30oz Mega: about 23 sq ft at 1 inch, with roughly 20% more foam per can.

All three are closed-cell foams rated R-5.66 per inch. Pick the Mega can for larger areas, where fewer can changes save time. For touch-ups and smaller projects, the 25oz cans are the better value.

1. Shake the new can for 30 to 60 seconds before you start.
2. Close the flow-control knob on the gun.
3. Unscrew the empty can, then immediately screw on the new one. The goal is to keep the gun open to air for as few seconds as possible.
4. Spray a short test bead onto cardboard before going back to the wall.

Never leave the gun without a can attached. If you're stopping for the day and won't finish the can, leave it on the gun with the knob closed, or run gun cleaner through it if you're done for good.

Once fully cured, after about 24 hours, the foam is rigid and water-resistant. You can trim it with a knife or saw, sand it flush, and paint it with latex paint.

Outdoors, don't leave it bare. Sunlight breaks down cured foam over time, turning it yellow and then brittle, so paint it or cover it. Indoors in living spaces, building codes generally require a thermal barrier such as drywall over the foam.