Foam guns

Mounting foam – household or professional – is necessary when installing plastic windows, replacing old doors, sealing and insulating. To work with professional varieties, a special tool is used – a mounting gun.

The device of guns for polyurethane foam

Before studying the functioning of the tool, it is advisable to familiarize yourself with its general structure.



The foam gun got its colloquial name for its resemblance to a handgun. There are a number of common nodes that are similar to each other in purpose and device:

  • Trunk. Through it, a liquid substance is “shot” under pressure, which subsequently polymerizes into a solid foam structure.
  • trigger. Trigger that actuates the mechanism for releasing foam from the cylinder.
  • Handle (pistol). Designed to hold the instrument in hand. Allows manipulation with one hand.
  • Adapter. An analogue of a pistol clip. In this case, its role is assigned to a foam cylinder.

The tool also provides a mechanism for adjusting the supply of foam – a fixing screw. It controls the rate and volume of foam release. The barrel ends with a fitting through which polyurethane is ejected.

Principle of operation

Work algorithm

Before starting work, the cylinder is kept up to 6 hours in a room with a positive temperature. Shake vigorously 15-30 times, after which the protective cover is removed from the cylinder head.

It is fixed with threaded parts until a tight connection. The working position will be signaled by a characteristic sound in the form of a short hiss.


  • By gently pressing the trigger, the release mechanism is activated, the valve opens the way for the contents of the cylinder into the barrel.
  • During movement inside the tube, the prepolymer “boils up” and passes into a foamed state – primary expansion occurs.
  • The flow of polymer, leaving the fitting in the form of a thin jet moving at a certain speed, receives the main increase in volume. It expands to 60–90% of final values.

The direction is determined by the operator who controls the tool. The output speed and volume of material is regulated by the fixing screw and the degree of opening of the cylinder by means of a trigger mechanism. The last steps depend on the experience and skills of the master.

Types and characteristics of foam guns

Types and characteristics

The design of the tool is collapsible or non-collapsible. The latter is a disposable pistol used for short-term operations. The device is an inexpensive form, made almost entirely of plastic.

There are no adjustment functions, it cannot be repaired.

Collapsible type – a reusable device that is subject to repeated use and repair. It is made of metal or special high-strength plastics. It is possible to replace individual parts of the structure.

Applicable material

Applicable material

The material used affects the durability, strength, performance and cost of the tool. Main types:

  • Inexpensiveth plastic. Used for disposable designs. It is beneficial to use in the repair of one dwelling. There are enough opportunities to install 2-3 plastic windows, replace 1-4 door blocks, and seal the balcony.

But the work must be done in one or two days. With long periods of time, the internal cavities will become clogged with hardened foam, and the device will fail.

  • Metal-plastic. An inexpensive type of tool with which you can repair a multi-room apartment or cottage. Repairable, requires washing after use. It is recommended to remove the cylinder with the remaining foam.
  • Metal. Professional grade tool. Expensive, but justifies itself in case of intensive use. Designed for people who constantly work with mounting foam.

Subject to the rules of operation and careful attitude, it can last up to 6-8 months.

  • metal-teflon. The metal parts in contact with the polyurethane substance are coated with Teflon. Thanks to this, the cured sealant is removed without a trace. Beneficial for continuous operation – the tool is expensive and will not justify itself in one-time operations.
  • High strength plastic. The use of durable polymers for the main parts – handle, body, adapter – allows you to reduce the cost of the tool without losing functionality.



The manual type of mounting guns is used when working with a portable container. This increases mobility at work. The assembled device is compact, the overall dimensions do not exceed 50 cm.

The industry produces another type of product used when working with an external compressor – an air gun.

The difference from the manual one is the absence of a long metal tube through which the liquid polymer is ejected, and the presence of fittings to which a hose is attached to supply air with high pressure.

Principle of operation:

  • The prepolymer flows through the valves to the outlet of the gun, where it is picked up by a jet of compressed air and crushed into small particles.
  • The flow moves at high speed towards the treated surface.
  • Drops stick to the plane, the substance interacts with atmospheric moisture, resulting in the formation of a porous structure.

This operation is used to form a heat-insulating layer. The latter is characterized by high thermal insulation, good adhesion to the base and a single monolithic composition.

Equipment and accessories

Complete set, accessories

The hand tool is supplied in a cardboard or plastic package (blister) with fastening elements for trade and exhibition equipment.

To perform work in hard-to-reach places, some models are equipped with nozzles:

  • Conical shape. They serve to fill narrow gaps, cracks, holes of small diameters.
  • Extension in the form of a flexible tube made of polymer. It is used when working in hard-to-reach places.

Nozzles are reusable: after use, they must be cleaned with acetone or a special tool in a small container.

In case of untimely cleaning of fixtures with a liquid agent and the foam hardens, the latter is removed mechanically. To do this, the nozzles are kept for 2-7 days until the final setting and drying of the polymer.

After that, with a sharp object, the cured sealant is removed.



  • Professional polyurethane has a denser structure, since the inner cells during polymerization are smaller than from a household cylinder.
  • The foamed product at the exit receives an expansion ratio of 60-80% of the final volume. Therefore, the expansion forces on the mounted structure will be minimal.
  • Determining the right amount of household foam requires a good knowledge of the properties of the product itself and solid experience.

A professional product uses the material more accurately and optimizes its application by distributing foam volumes to several processed objects.

  • It is much more practical and convenient to work with a pistol, since only one operator’s hand is occupied. Additional operations are performed with the free hand, for example, the workpiece is fixed.

A specialized tool of the middle price class will pay for itself when repairing a 2 or more room apartment or building a country house. For craftsmen whose income consists in carrying out finishing work, this type of device is essential.



During operation, there are some problems associated with the inconvenience of using the assembled structure:

  • The balloon with foam in relation to the horizon should occupy an almost vertical direction. When working under the ceiling, it becomes difficult to use the gun.

To eliminate this drawback, it is necessary to use an extension tube. But then the ease of use is lost, in this case the operator has both hands occupied.

  • The assembled structure, together with a human hand, occupies a space of 35-45 cm in two planes, which significantly limits its use in narrow places. The standard extension cords included in the delivery set are of little use in this case.


A medical tube from a dropper can help in such a situation, but its length should not exceed 50-60 cm. Otherwise, there will not be enough pressure inside the balloon to push the foam.

  • During breaks in work for more than 2 days and emptying the container by half or more, the tool must be disconnected from it and cleaned. In this case, the remainder of the polyurethane disappears, it will not be possible to reuse this cylinder.

Other problems are human forgetfulness. For example, an error in the calculation of the required amount of sealant or the lack of a cleaner leads to additional time.

How to choose

How to choose

When inspecting, it is required to pay attention to the completeness of the information indicated on the packaging. In addition to the characteristics and description of the design, information about the country of manufacture, the name and address of the company must be present.

The primary indicator of the tool’s performance is tightness and the ability to hold internal pressure.


  • In production, products are pressed, so when you press the trigger of a new product, excess air exits through the barrel with a characteristic hissing sound. This indicates tightness and the ability to work under pressure.
  • An additional check is working with a cleaner. To do this, a container with a liquid inside under pressure is installed on a new product. By pressing the trigger, the release mechanism is activated.

A serviceable device ejects the stream only through the barrel. The appearance of moisture in other places of the structure indicates its malfunction.

  • The material from which the gun is made speaks of the expected service life and strength. Cheap plastic is a sign of a disposable device. Conversely, a durable polymer indicates a long service life.

Which is better

Which is better

When choosing the best device, you should focus on the following parameters:

Construction material and a combination of the “price-quality” indicator (in descending order):

    • teflon coating;
    • all-metal product;
    • high strength polymer;
    • metal-plastic;
    • inexpensive plastic.

    maintainabilitythat is, the ability to disassemble and replace individual parts.

    Presence of a mechanism adjusting the volume and feed rate of polyurethane foam.

    Manufacturer brand. The manufacturer, which has been operating on the market for a long time, strives to produce only high-quality and reliable products.



    When working, it is necessary to observe safety precautions:

    • The prepolymer is in a closed vessel under pressure, so it can be heated in an environment with a temperature not exceeding 30-35°C.
    • Polyurethane, which is in a gas-liquid state, is a flammable and explosive substance. You can not fill the gun, perform operations near heating devices, especially near an open flame.
    • It is not allowed to direct the equipped tool at a person, animals, heat-producing devices. Accidental actuation of the trigger or spontaneous operation of the product may result in serious injury.


    • The replacement of an exhausted cylinder must be done carefully and as quickly as possible: under the influence of residual pressure, there is a risk of splashing onto surrounding objects.

    Resin residues can dry quickly in air, resulting in a loss of time to clean the tool.

    Application rules

    Application rules

    • The foam can goes up.
    • At the end of shaking, the container is screwed onto the adapter without undue effort. A characteristic hissing sound will signal the correct connection.

    The absence of such a signal indicates a malfunction of the tool, clogging of channels or valves, the end of the warranty period for foam.

    • The feed regulator is opened by turning one quarter of a circle. By directing the nozzle into an unnecessary container, it is necessary to achieve the required flow consistency.
    • The prepolymer is directed deep into the space to be filled. The amount of sealant should not exceed half of the total free volume.

    End of work

    End of work

    It is not recommended to remove the container with the unused substance from the tool if the interval between operations does not exceed 3-7 days. The tip of the nozzle does not need to be cleaned of sealant residues – this will increase the tightness of the device.

    When all the polyurethane is used up, the cylinder is dismantled, the tool is washed with a cleaning liquid. The flow regulator is closed.



    The warranty period for the product is indicated in the accompanying documentation (passport, instructions, on the packaging). But this only applies to branded products.

    Replacement or repair is subject to products that have:

    • external damage;
    • failure of the trigger mechanism, including the trigger;
    • discrepancy between the threaded parts of the adapter and the foam;
    • seal failure.

    The latter conditions are checked in the presence of the seller or at home. The claim must be made within 7 days after the sale. Claims will not be accepted if there are signs of external interference or self-repair attempts.

    Faults and repairs

    Malfunctions, repair

    Refusal appears after breaks in work. It consists in not passing foam through the device. The reasons are clogging of the internal cavities of the structure with a hardened sealant. The correction of this shortcoming is the disassembly and cleaning of the gun.

    For such operations you will need:

    • cleaning fluid and/or acetone,
    • a knife with a thin and sharp blade,
    • awl or sharp self-tapping screw with a long threaded part.

    The hardened polymer is removed mechanically, the cavities are washed with liquid.

    In case of mechanical failure, the tool is disposed of or sent for spare parts. Repairs in most cases are not carried out due to the fact that components are difficult to find. Therefore, a new design is acquired.

    Foam gun manufacturers



    A Canadian company that produces tools for construction and household purposes, including those for working with foam:

    • nozzle guns for operations with standard cylinders without special fastening;
    • household class tool;
    • products for craftsmen-finishers;
    • Pro class.

    Official dealer of FINCH INDUSTRIAL TOOLS CANADA INC in Russia.



    The tool of the German company can be safely attributed to the professional series. This is evidenced by the Teflon coating of all manufactured models made of metal. Suitable for craftsmen who constantly work with foam products.



    A German company produces tools for semi-professional and professional use. Almost all parts are made of metal, except for plastic handles.



    One of the most famous companies in the Russian Federation, headquartered in Germany. It produces different models: lightweight “disposable” devices with a housing made of inexpensive plastic and professional metal structures for permanent use.



    The company’s brand is registered in Germany. Produces three models:

    • household class with a housing and an adapter made of inexpensive polymer;
    • semi-professional series with a metal body, a Teflon-coated needle and additional nozzles;
    • pro grade with full teflon coating.



    A Russian company focused on the mass and professional consumer of various tools and household goods. Produces several series of tools:

    • Expert,
    • Standard,
    • Master,
    • Professional.

    The series differ from each other in the presence of a special treatment (barrel polishing or adhesive coating), sealing rings, body material.

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