How to clean a foam gun before the foam cures
Updated: 23 October 2026
You have just laid a bead, or you have found yesterday's foam gun solid in the shed. The difference is whether the polyurethane inside is still wet. This is how to clean a foam gun while solvent can still do something, and when to stop forcing a trigger that has seized. None of the eleven guns in the [foam gun comparison](/hub/fillers-adhesives-and-sprays/foam-gun) includes a cleaner. Peter F. used Soudal, Penosil, Bond It and Health and Safety Executive guidance, plus the review notes. We did not strip a gun in a workshop. A qualifying purchase can earn us a commission at no extra cost to you.
You have just laid a bead, or you have found yesterday's foam gun solid in the shed. The difference is whether the polyurethane inside is still wet.
You have just laid a bead, or you have found yesterday's foam gun solid in the shed. The difference is whether the polyurethane inside is still wet. This is how to clean a foam gun while solvent can still do something, and when to stop forcing a trigger that has seized. None of the eleven guns in the foam gun comparison includes a cleaner. Peter F. used Soudal, Penosil, Bond It and Health and Safety Executive guidance, plus the review notes. We did not strip a gun in a workshop. A qualifying purchase can earn us a commission at no extra cost to you.
Our top picks
| Badge | Product | Cleaner in box | Coating stated | Shut-off | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  fischer fischer PUP M3 metal foam gun | No | PTFE basket | Not listed | 8.6 | about £19.84 | View offer |
| Best value |  Lytool Lytool PU expanding foam gun | No | Not stated | Barrel valve | 8.1 | about £14.29 | View offer |
 Grapelet Grapelet PU foam gun | No | Not stated | Not listed | 6.8 | about £8.99 | View offer |
On this page
Leave the can on or take it off
If the can is still part full and you will shoot again soon, leave it screwed on. Soudal and Penosil both take that path. Close the flow screw and wipe the tip. fischer's page for the PUP M3 says an opened can can stay on during a break. Take the can off when it is empty, when you are changing foam, or when the gun will sit for a long gap. Soudal says to empty the can before you unscrew it, because foam can spray as the valve releases. Fitting the can stays on how to use a foam gun.
Flush while the foam is wet
Gun cleaner is a separate acetone aerosol. It is extremely flammable. Follow the can you bought. Penosil: shake the cleaner, screw on with the valve up, and shoot with the cleaner upside down until the liquid runs clear. Wait about two minutes, then spray again. Bond It: pull the trigger while you screw the cleaner on, let it sit about two minutes, and repeat until clear. Soudal's sheet: pull the trigger several times with pauses of about 10 to 15 seconds, and use the black adapter on the outside. A clear stream means uncured foam is leaving. Test the cleaner on a hidden spot of uPVC or paint first.
What cleaner will not do
Acetone dissolves uncured foam. It does not dissolve foam that has cured inside the barrel. Soudal's sheet says cured foam has to come off mechanically. Bond It says not to use sharp instruments on the coating. A PTFE title does not change that rule. GDUSMCN's bullets say residue peels without harsh solvent. Cleaner is still not in the box. Do not soak the gun in a jar of neat acetone. The buying checks that reject a no-cleaner title are on the foam gun buying guide.
If the gun is already blocked
Forcing a seized trigger is how a cheap gun snaps. Grapelet reviews include a gun that blocked on first use and one that snapped when the buyer tried to strip it. If the barrel is solid, the solvent can will not restore it. Replace the gun when cleaner will not open a path. Guns with larger review files are on the best foam gun page. Do not puncture empty aerosols. Bond It's sheet says that from 24 August 2023 adequate training is required before industrial or professional use. A householder flushing one gun is not that course.
Common questions
Do I clean the gun after every bead?
Not if the can stays on and you will shoot again soon. Close the flow screw and wipe the tip. Clean when the can is empty, when you change foam, or when the gun will sit for a long gap. Leaving wet foam in an open gun overnight is what cures the needle. A wipe of the tip is not a flush of the barrel.
Can I leave the can on the gun overnight?
Yes, if you will use the rest soon. Soudal and Penosil both describe leaving a part-used can fitted, with the adjustment screw closed. It is not a guarantee that every gun will still flow after weeks. Some fischer reviews mention three weeks. Others report a gun that failed after one use. If you are finished for the season, empty and flush instead.
Does acetone or gun cleaner remove cured foam?
No. It dissolves foam that is still wet. Soudal's data sheet says cured foam comes off mechanically. Picking a cured skin off a frame is possible with care. Picking it out of a needle usually ruins the gun. Do not put acetone on your skin. Soap and water are what HSE and Soudal say to use on hands.
How do I flush the gun?
Use a foam-gun cleaner can, not a guess. Penosil says shoot with the cleaner upside down until it runs clear, wait about two minutes, and shoot again. Bond It says pull the trigger while screwing the can on, then wait about two minutes. Soudal's sheet uses short bursts with 10 to 15 second pauses, and an adapter for the outside. Follow the can you have. Stop when the stream is clear.
Can I soak the gun or pick the needle with a knife?
Do not pick the needle with a knife. Bond It says sharp instruments damage the coating. Do not soak the gun in a jar of acetone. Grapelet reviews include a gun that snapped when someone tried to strip a blockage. If the foam inside has cured, solvent and force are both poor bets. Replace the gun rather than lever the trigger until the body breaks.
What if the gun is already solid inside?
Treat it as finished if cleaner will not pass. Cured foam in the barrel is not something acetone dissolves. Forcing the trigger can snap the gun, which is already in the review notes for a seized Grapelet. A replacement still needs cleaner in the same order, and a part-used can left on between beads. Repeating the dry storage is what blocks the next one.
Is cleaner safe on uPVC and paint?
Not automatically. Soudal says to test plastics, lacquer and paint first. Acetone can dull a frame if you flood it. Wipe splashes while they are wet, on a spot you have checked. Keep the spray on the gun and the tip. Empty cans should not be punctured. Council rules differ, and expanding-foam tins often go to a household recycling centre rather than the kerbside sack.
Related pages
Sources
Public UK sources used for this comparison. amazon.co.uk prices, stars and review counts were taken from the listings on 19 October 2026.
- HSE, Isocyanates (retrieved 19 October 2026)
- HSE, occupational asthma substances (retrieved 19 October 2026)
- Penosil UK, straw foams vs gun foams (retrieved 19 October 2026)
- Screwfix, how to use an expanding foam gun (retrieved 19 October 2026)
- Soudal UK, storing an opened can (retrieved 19 October 2026)
- Soudal Gun & Foamcleaner TDS (retrieved 19 October 2026)
- fischer UK, PUP M3 33208 (retrieved 19 October 2026)
- Environment Agency aerosol canister guidance (retrieved 19 October 2026)