Hot Melt Glue Gun Cleaning and Maintenance Routine

Hot melt glue gun care, cleaning and maintenance.

An industrial hot melt gun needs little cleaning, because normal hot melt remelts next time. What it needs is good habits: keep the nozzle pointing down and park the gun on its stand, listen for the vent after each trigger pull, turn the temperature down in long breaks, keep the glue clean, and replace the nozzle and seals when they wear. PUR is the exception: flush it before the gun stands idle.

For industrial hot melt guns such as Reka: MS 80 and MS 200 hand guns, air-driven TR guns and cartridge guns.

A hot melt gun that is looked after gives the same bead day after day and lasts longer. One that isn’t starts dripping, blocking and stopping the line. The good news: the care it needs is mostly habit, not work.

Every time you use it

Nozzle down, always. Never hold the gun level or nozzle-up, and never lay it down while the glue is liquid. Liquid glue runs into the vent valve on the lid and blocks it. This single habit prevents the most common fault we see: a gun that keeps dripping.
Park it between jobs. Put it on its stand, wire stand, magnetic plate or balancer, never on its side.
Listen for the vent. On air-driven guns, the gun must vent audibly through the vent valve after each trigger pull. If it goes quiet, the vent may be blocking; clean it before glue starts to escape. See vent valve cleaning.
Let the glue melt fully. Never force the trigger on half-melted glue; it damages the gun.
Keep the glue clean. Close the bag after each fill and never load dirty glue. See storing hot melt adhesive.

During breaks

Turn the temperature down in long breaks. Glue held hot for hours chars into brown flakes that block the nozzle.
Don’t leave a hot gun unattended.

At the end of the shift

Switch off and unplug. Pull the plug, not the cord.
Leave normal hot melt in the gun. It remelts next time, so the gun needs no cleaning.
PUR: flush before it stands. Run a cleaner cartridge through the nozzle and adapter (about 20 minutes), especially before a weekend or a long idle spell. Cured PUR cannot be remelted.
Park it upright. Put it on its stand, so any glue left in it stays away from the vent.

How to clean it

Inside, with normal hot melt: nothing to do. The glue left in the gun remelts next time.
Polyamide glues: they char easily and may need a special cleaning agent. Reka’s is Dyeclean #2265 (see spares). Never a solvent (below).
PUR: flush the nozzle and adapter with a cleaner cartridge (about 20 minutes) before a weekend or a long stop. Cured PUR cannot be remelted.
A blocked nozzle: replace it. On air-driven guns you can also flush it: fill halfway, 20 to 40 °C below working temperature, one pass at 6 bar. See changing a nozzle.
The vent valve (air-driven guns): clean it with the gun warm when it stops venting. See vent valve cleaning.
Burnt glue: brown or black flakes mean the glue was kept too hot or too long. See brown flakes.
Changing to a different glue: use up or empty the old one first; on cartridge guns, flush the nozzle and adapter. See storing hot melt adhesive.

Regular checks

Check	What to look for	What to do
Nozzle	Dripping, less glue, a bead going off at an angle	Replace the nozzle; see changing a nozzle
Vent valve (air-driven)	No venting sound, glue at the lid	Clean the vent or fit a new silencer and seals, with the gun warm
Lid (MS guns)	Glue in the lid’s venting hole: low flow or a leaking nozzle	Clean or change the lid
Cable and air hose	Cuts, kinks, damage at the plug	Stop using the gun until it is replaced
Compressed air	Water or oil in the line	Use an oil and water separator; 2 to 6 bar
Glue colour	Brown flakes, dark glue	Lower the temperature; see brown flakes
MS guns: casing	Hot melt leaking out of the casing	Stop at once: the piston O-rings are worn and need a repair

Never do this

Never clean with solvents (benzine, benzene, toluene, acetone, turpentine and similar): there is a risk of explosion.
Never go above the adhesive’s working temperature.
Never open the gun beyond the parts the manual lets you change (nozzle, lid, vent-valve parts). Home repairs void the warranty; send the gun to us instead.

Keep these spares at the factory

A spare nozzle of each type you use costs little and turns a blocked nozzle into a quick change. On air-driven guns, keep a complete spare lid at hand: when a vent blocks, swap the lid and clean the old one later. Wear-part sets are available by model: see spares and genuine spares and wear parts.

When to call us

If the gun doesn’t heat, shows an error, or a fault comes back after these checks, stop and tell us. Shut the gun down at once if an air-driven gun’s temperature drops to 130 °C and climbs again, or an LCD model shows 2.5.9 and blinks.

Questions.

How do I clean a hot melt glue gun?

With normal hot melt there is nothing to clean inside: the glue left in the gun remelts next time. Wipe the outside of the nozzle and the housing with a cleaning agent made for hot melt, never a solvent. With PUR, flush the nozzle and adapter with a cleaner cartridge before a long stop. Replace a blocked nozzle, and keep the vent valve clean on air-driven guns.

Do I need to clean my hot melt glue gun after every use?

Not with normal hot melt: the glue left inside remelts next time. PUR is different: flush the nozzle and adapter with a cleaner cartridge before a long stop.

How do I know the vent valve is working?

On air-driven guns, you should hear the gun vent after each trigger pull. If it doesn't, the vent may be blocked; see vent valve cleaning.

How often should I change the nozzle?

When it wears or gets a foreign object in it. The signs are dripping, less glue than usual, or a bead that goes off at an angle.

Why is there brown, burnt glue in my gun?

The glue was heated above its working temperature or held hot too long. Lower the temperature, and turn it down during long breaks.

Which spare parts should I keep at the factory?

At least one spare nozzle of each type you use. On air-driven guns a complete spare lid saves the most downtime when a vent blocks.