Gun foam or hand-held foam – which is better?
Gun foam pays off as soon as you use more than one can or work in stages: the opened can stays ready for use on the gun, dosing is finer and the foam can be cut sooner (approx. 30 instead of approx. 45 minutes). Hand-held foam with an adapter tube suits exactly one joint or a single repair. Technically both foams are close together, the difference lies in the application system.
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What you need
Project template “Apply PU foam”In short: Gun foam wins as soon as you use more than one can or work in several stages – the opened can stays ready for use on the gun, dosing is finer and the foam can be cut sooner (approx. 30 instead of approx. 45 minutes). Hand-held foam with an adapter tube is the right choice for exactly one joint, a single wall opening or a repair where buying a gun does not pay off. Technically the foams are close together: same building material class B2, same temperature resistance, almost the same thermal conductivity.
The question sounds like a question about the foam – but it is above all a question about the application system. With one and the same product family, the Soudal Soudafoam B2, both variants exist in the 750 ml can: one with a screw valve for the dosing gun, one with an adapter tube for the hand. It is precisely this pair that we compare here, because that shows the difference cleanly, without two different recipes distorting the result.
Both variants compared directly
Soudal Soudafoam Gun B2 – gun foam
- Application via dosing gun with trigger and adjusting screw
- Approx. 40 litres yield from the 750 ml can
- Skin formation after approx. 8 min., cuttable after approx. 30 min., loadable after approx. 12 hrs.
- Bulk density approx. 23 kg/m³, thermal conductivity 0.037 W/(m·K)
- Opened can stays screwed on and remains usable
Soudal Soudafoam B2 – hand-held foam with tube
- Adapter tube is screwed directly onto the can, no gun needed
- Tack-free after approx. 20 min., cuttable after approx. 45 min., loadable after approx. 24 hrs.
- Bulk density approx. 25 kg/m³, thermal conductivity 0.035 W/(m·K)
- Application temperature +5 °C to +30 °C
- Ready for use immediately – but only limited shelf life once opened
Important for putting it in context: Both cans contain 750 ml and come from the same product family. The difference lies not in the price of the foam but in the application system – and in whether you additionally buy a foam gun.
Detailed comparison of the technical data
| Feature | Soudafoam Gun B2 (gun) | Soudafoam B2 (tube) |
|---|---|---|
| Contents | 750 ml | 750 ml |
| Application system | Screw valve for dosing gun | Adapter tube, directly from the can |
| Basis | 1K PU on MDI basis, self-expanding | 1K PU rigid foam, moisture-curing |
| Bulk density | approx. 23 kg/m³ | approx. 25 kg/m³ |
| Skin formation / tack-free | approx. 8 min. | approx. 20 min. |
| Cuttable | approx. 30 min. | approx. 45 min. |
| Loadable | approx. 12 hrs. | approx. 24 hrs. |
| Thermal conductivity | 0.037 W/(m·K) | 0.035 W/(m·K) |
| Building material class | B2 to DIN 4102-1 (test certificate P-SAC 02/III-010, MFPA Leipzig) | B2 to DIN 4102-1 (test certificate PSAC 02/III-115, MFPA Leipzig) |
| Temperature-resistant (cured) | -40 °C to +90 °C | -40 °C to +90 °C |
| Yield | approx. 40 litres per can | Manufacturer's figure in the data sheet |
| Preparing the can | shake at least 20 sec. | shake approx. 30 ×, valve pointing down |
| Degree of joint filling | approx. 65 % | approx. one third |
| Colour / UV | champagne, not UV-resistant | champagne, not UV-resistant |
| Opened can | stays screwed onto the gun and remains usable | Tube cures, remaining contents usually lost |
All values from the manufacturer data sheets of the products. The data sheets state compressive strength in different units and test methods; a direct numerical comparison would be misleading at this point and is therefore omitted.
The decisive difference does not lie in the foam
The table shows it clearly: chemically, little separates the variants. Same building material class, same temperature resistance, thermal conductivities that differ by two thousandths. Anyone who looks only at the insulating effect can take either can.
What tips the balance are three practical points:
1. The opened can
A can of gun foam stays screwed onto the gun during breaks in work – the system is closed, and the foam as a rule does not cure in the barrel. With straw foam the foam cures in the adapter after use. Anyone who needs only 200 ml of 750 ml practically throws the rest away.
2. The dosing
At the tube you dose with your finger on the valve. At the gun an adjusting screw limits the flow and the trigger regulates the quantity. With narrow connection joints and overhead, that is the difference between a clean bead and foam on the frame.
3. The time window
The gun foam is cuttable after approx. 30 minutes and loadable after approx. 12 hours – the straw foam needs approx. 45 minutes and approx. 24 hours respectively. On a building site with the next trade the following morning, that is a real argument.
Recommendation by application
| Your project | Recommendation | Why |
|---|---|---|
| One joint, one pipe penetration, one repair | Hand-held foam with tube | No tool needed, ready for use immediately; buying a gun does not pay off with one can. |
| Several windows or doors, construction phase over several days | Gun foam + foam gun | Can stays usable, finer dosing, shorter waiting times until cutting. |
| Deep wall openings, hard-to-reach cavities | Gun foam, gun with extended barrel | Reach and control; with the short tube you do not get in deep enough. |
| Living space with demands on healthy living | Isocyanate-free SMX assembly foam | 100 % isocyanate-free, halogen-free, EMICODE EC1 Plus, considerably more UV-resistant than classic PU foam. |
| Door frames that need to be loadable quickly | 2K foam (adapter foam) | Cures independently of humidity: cuttable after approx. 9 min., fully loadable after approx. 3 hrs. |
| Occasional use, but the gun is to last | Gun with PTFE coating | The foam hardly adheres inside, cleaning is easier – the gun also survives longer idle periods. |
If you decide on gun foam: the gun does not fit everything
A foam gun fits only gun foam cans with a screw valve. Hand-held foam with an adapter and tube cannot be applied with it – that is not a compatibility detail but a purchasing decision: anyone who owns a gun must consistently order gun foam when buying more.
When buying a gun it is worth looking at the body and the inner coating. A metal gun with a PTFE-coated inner tube hardly glues up with cured foam and can be cleaned with commercially available gun cleaner. For deep openings there are versions with a barrel up to 60 cm long.
View professional foam gunCommon mistakes – and how to avoid them
Further reading
- Which PU foam for window installation?
- How to: apply PU foam correctly
- PU foam does not cure – causes and solution
- Removing PU foam – fresh and cured
- How to: RAL window installation – procedure and materials
- All gun foams in the shop
Frequently asked questions
Can I apply gun foam without a gun?
No. Gun foam cans have a screw valve that cannot be operated without a gun. There is no adapter tube that replaces this valve. The same applies the other way round: hand-held foam with a tube adapter does not fit a foam gun.
Do I have to clean the foam gun after every use?
Not necessarily. As long as the can stays screwed on, the system is closed and the foam as a rule does not cure in the barrel. Cleaning is done when changing the can and before longer storage – with gun cleaner, not with water. Cured foam can only be removed mechanically.
How much foam do I get from a 750 ml can?
With the Soudafoam Gun B2 the manufacturer states around 40 litres of free-foamed volume per 750 ml can. How much of that arrives in the joint depends on the degree of filling: you deliberately fill only to about 65 percent, because the foam keeps expanding.
Does one foam insulate better than the other?
Practically not. The gun foam is at 0.037 W/(m·K), the straw foam at 0.035 W/(m·K) – a difference that plays no role in the connection joint. What is decisive for the insulating effect is that the joint is filled without voids and evenly. It is exactly there that the gun helps.
What does building material class B2 mean?
B2 to DIN 4102-1 stands for “normally flammable”. Both foams compared here are tested to B2 (MFPA Leipzig). If the building authorities require a flame-retardant foam – for example in public buildings –, you need a B1 fire-protection foam; B2 is not enough there.
At what temperature may I apply it?
The straw foam is approved for +5 °C to +30 °C. In frost or below, reach for a winter foam designed for low temperatures. Both cans are stored upright, cool and dry.
What do I do with empty foam cans?
PU foam cans do not belong in household waste. The Soudafoam B2 assembly foam carries the PDR marking: empty cans can be disposed of via the PDR take-back system.
Technical information according to manufacturer data sheets, product data as of September 2026. For questions about the choice you can reach us on +49 (0) 2831 - 916 77 03. Baustoffheld, Lindenstrasse 56, 47623 Kevelaer.
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