As you know, polyurethane foam hardens quite quickly in the open air, which is good when applied to building structures. But if this happens inside the construction gun, then there will be no way to continue working on filling the cracks or sealing the joints.
Is it really because of this that you will have to buy another tool, the price of which starts at 500 rubles? What if the same thing happens to the second one? So it won’t take long to go broke on pistols.
But not everything is so gloomy. Firstly, there is a universal foam cleaner in cans, which costs about 300 rubles. Its contents may be enough for two or three cleanings, that is, each such procedure will cost you 100 rubles.
Is it possible to do without this expensive product if there is a need to clean the construction gun from the foam that has dried inside it? Yes, such a possibility exists. You can make a very simple device yourself, which will cost you a total of 5 rubles and can be used as many times as needed.
Working on a gun flushing device
To make it, you will need an old polyurethane foam container, or rather, its upper part, which can be easily and accurately cut off using a carpenter's knife.
We clean it of old foam and remove the valve using the following simple manipulations.
We insert the rod into the hole and knock it with a hammer until it rests against the valve.
Then, on the reverse side, we tear off the yielding valve using pliers. Moreover, the short side tube that opened after removing the valve should remain in place.
Next, we glue in a 20-milliliter medical syringe, since it is the one that fits tightly into the valve hole. A syringe with a volume smaller than the specified one will dangle, and a larger one will not go in.
After these manipulations, using a glue gun, fill the junction of the syringe and the valve with epoxy resin or some other suitable means. It is necessary to give some time for the glue to harden, after which the device is completely ready to work on washing the construction gun from the foam that has dried in it.
In principle, you can limit yourself to just sealing the tip of the syringe in the hole where it is inserted. But it will be safer to fill the joint completely with glue, since the device will have to be screwed in and out, applying some effort. In addition, when flushing, quite high pressures arise in it.
The process of cleaning a gun from dried foam
Next, you need to unscrew the gun with the remaining and hardened mounting foam from the can as quickly as possible, since the valve often does not work. Pour about one syringe of solvent into the can to clean the valve.
Then we install our device on the construction gun and screw it in until we hear a hissing sound, which indicates that the device is screwed in completely.
Fill the syringe with solvent “646” using another syringe, insert the plunger and begin to rinse the gun. To do this, pressing the piston, we press the trigger of the gun. The solvent supplied in portions will gradually help remove hardened foam from the gun channels, first liquefying it. To completely clean the instrument, two refills of the syringe are enough.
Usually, after using our device, in order for it to be ready for use next time, it must be rinsed and finally filled with a full syringe of water and left until the next use.
Final remarks
Still, the syringe in the lid must be filled with the same epoxy resin. Here, retention and tightness will be ensured by a large volume of glue. Otherwise, nothing will work: it’s practically impossible to glue plastic to plastic using anything.
The experience of many craftsmen shows that if a can of polyurethane foam is screwed on correctly, then it does not harden during storage for months. Only at the end of the tube can a film form, which cannot be removed during storage. It is this that prevents air from entering the instrument and protects the foam in the gun from hardening.
