How to Fix a Jammed Spray Foam Insulation Gun

What You'll Need
Bottle brush

Spray foam insulation is a specialized material that is used in packing and construction. Made from liquid foam, it is engineered to expand multiple times the volume of its liquid state. It is an excellent insulator as a result, especially in the transportation of fragile items like computers and marble busts. In the construction, a spray gun is used to spray foam, which minimizes air infiltration into the building.

Troubleshooting the Spray Foam Gun

If the spray foam jet from your gun is sticky and does not solidify quickly following ejection or if the foam is darker or lighter in color than the rich cream that is its normal appearance then you have a problem with your gun. To test for blockage, remove the nozzle of the gun and on an ordinary cardboard, pull the trigger. Two jets of equal force foam should be emitted at the same time. If this is not the problem, then the following steps should assist in ‘unjamming’ your gun.

Step 1 - Inspect the Nozzle

The nozzle of the spray foam gun should be the first stop when your gun jams. Because the 2 chemicals that create the foam begin to harden almost immediately when they come into contact with each other, residue may have simply accumulated in the gun’s nozzle.

Step 2 - Clean the Nozzle

Separate the nozzle and the hose from the gun assembly then dip it into your basin of water. Use the cloth to clean the outside and a bottle brush or something similar to clean the inside. Try and clean the nozzle every time you want to spray your foam. If you encounter stiff blockage then you will have to replace the gun as the nozzle and the hose are not commercially available as spare parts.

Step 3 - Inspect the Tanks

The tanks that contain the foam chemicals attach to the spray foam gun via a hosepipe. This pipe may have detached, causing the gun to jam and simply needs to be reattached again.

Step 4 - Inspect the Chemicals

Most commercial spray foam guns are of impingement-mixing technology where the two chemicals that make up the foam mix within the gun and dispense on a one-to-one ratio. The minute the two chemicals come together, they react as they are expelled from the gun. Ensure that these chemicals do not harden in the tank and in turn jam the gun.

Step 5 - Purge the Residue

In the instance where not all the blended chemical managed to exit the tank, hardening in the process, the resultant residue has to be eliminated through a technology known as purging. There are three types of purging: air, mechanical and solvent purge. Contact your foam manufacturer for specific instructions under this circumstance. Note that these purge systems come with their own advantages and disadvantages.


Always shake the tanks before you spray and every time after that to limit residue creation.

Keep in mind that the foam is susceptible to temperature changes and should only be used in conditions between 75 and 85 degrees Fahrenheit; otherwise, it will harden faster and block the spray gun’s nozzle.