How to Clean Hot Melt Adhesive Guns and Spray Paint Nozzles

Firms using hot melt adhesives and spray painting as part of daily routines know that cleaning their equipment after use can be more cost effective than constantly replacing precision components.  A cursory Google search discloses common cleaning recommendations include soaking in solvents and running wires through openings.  Here we describe how ultrasonic energy can clean hot melt adhesive guns and spray paint nozzles in minutes and more thoroughly than manual methods.

How Ultrasonic Cleaners Speed Removal of Hot Melt Adhesive and Paint Residues

Ultrasonic cleaning involves the implosion of minute vacuum bubbles when contacting the parts being cleaned.  Bubbles are created by ultrasonic transducers bonded to the bottom of a tank containing a solvent or a biodegradable ultrasonic cleaning solution.

Because the bubbles are so small they penetrate minute crevices and openings typical of adhesive gun and spray paint nozzles.  They blast loose and carry away residues difficult if not impossible to remove by simple soaking in solvents or using manual methods.

Important Cautions Using Solvents when Cleaning Adhesive Guns 

Several precautions must be taken when using adhesive gun cleaning solvents in an ultrasonic cleaner, especially solvents that are flammable and have relatively low flash points.  

The first rule is never put such solvents directly in a standard ultrasonic cleaning tank.  That is because they give off vapors that can explode due to a chance spark, and otherwise be dangerous to personnel. 

While there are ultrasonic cleaners especially designed for cleaning with flammable solvents, a less costly option is using special cleaning procedures in a standard Elma benchtop ultrasonic cleaner employing a flammable solvent beaker kit.

In any case, when employing a flammable solvent for cleaning purposes you should follow local safety recommendations as well as those of plant safety personnel.

A Suggested Procedure for Cleaning Adhesive Gun Nozzles 

Ultrasonic Cleaner Preparation:

1. Place the ultrasonic cleaner in an area with good ventilation and away from equipment that may cause a spark. Add water to the tank fill line along with a surfactant to improve the cavitation action.
2. Run the cleaner without a load until bubbles stop coming to the surface.  This degasses the liquid to improve cavitation. Many ultrasonic cleaners are equipped with a degas function to speed this process.

Cleaning Steps

1. Chill the nozzles and peel away easily accessed adhesive deposits.
2. Place the nozzles in beakers and add enough solvent to fully immerse them.
3. Loosely cap the containers to allow vapor to escape.
4. Fit the beakers into the kit’s beaker holder so that they are immersed 2-3 inches.  Beakers must not be in contact with the bottom of the tank.
5. Turn on the cleaner.  Cavitation energy in the aqueous solution penetrates the glass beakers and causes cavitation action in the cleaning solvent.
6. Set the timer, if so equipped, for 5 minutes.  Remove and inspect the nozzles.  You’ll soon be able to determine a recommended cleaning time.  When satisfied allow them to dry and they are ready for reuse.

Dirty solvents should be kept in a sealable container and held for proper disposal.

Spray Paint Nozzle Cleaning with an Ultrasonic Cleaner

As users will attest, paint spray guns are precision tools important to providing a smooth professional finish to metal, wood and other surfaces. 

To maintain peak performance paint sprayers must be cleaned on a regular basis.  An ultrasonic cleaner has proven highly effective in removing paint from tip holders and painting gun components as part of an organization’s equipment maintenance procedures.

How to Clean Water-Based Paints from Spray Paint Nozzles

When using a water-based paints with spray paint nozzles a cleaning method is using distilled or deionized water in a 1.5 gallon capacity Elmasonic E Plus Series cleaner such as the  EP60H operating at 37 kHz. 

Components are placed into the cleaning basket and lowered into the bath where cavitation bubbles created by generator powered ultrasonic transducers implode on contact with the components to blast away paint residue. 

This is much more efficient than using steel wool or brushes that can damage precision spray gun subassemblies. 

Removing Oil-Based Paints from Spray Paint Nozzles

Oil-based paints and lacquers require specially formulated biodegradable ultrasonic cleaning solutions such as the semi-aqueous micro-emulsion CLN-SC75 available to order online at iUltrasonic.com.  

Used full strength or diluted to 50% in an ultrasonic cleaner operating at a temperature of approximately 70˚C this solution lifts paint residues from spray gun surfaces. 

Removed residues can be filtered after a period of time and the solution reused until it is discarded following local regulations.  

An alternate is CLN RS-98. This formulation can be used full strength or diluted up to 50% with water and heated to 160⁰ – 180⁰F (71⁰- 82⁰C) until emulsified. As with CLN-SC75 this formulation can be filtered to and reused.

Cleaning times depend on the condition of the components but in any instance should be less and definitely more thorough than any form of hand scrubbing. 

At the end of the cleaning process rinse the components and allow them to dry.  You should also establish a procedure to replace spent cleaning solutions (with disposal according to local regulations) and cleaning the solution tanks following manufacturers’ recommendations.

Common Steps for Ultrasonic Cleaning Adhesive and Spray Guns

Whatever cleaning solution you use it should be degassed prior to the actual cleaning steps.  This removes entrained air that diminishes the effectiveness of cavitation action, thereby lengthening the cleaning process. 

If your ultrasonic cleaner does not have a degas function the process is accomplished by running the unit without a load until air bubbles no longer rise to the surface.  The degassing operation should be employed each time you prepare a new batch of solution.

Contact the ultrasonic cleaning experts at Tovatech for information on selecting ultrasonic cleaner models, cleaning solution formulations and procedures that keep your paint spraying equipment. We are the top authorized reseller in the United States.