Polyurethane foam appeared relatively recently. Moreover, as usually happens with interesting discoveries, it was invented by accident. The German inventor Otto Bayer succeeded in this. The latter experimented in the laboratory with polyurethane. In the 70s of the last century, scientists managed to place this mixture in an aerosol can. This caused widespread demand for it in society. In Russia, the first sales of polyurethane foam began in Moscow during the Soviet era. However, it soon began to appear in other cities of the country. Today, polyurethane foam is used for insulation, sound insulation, installation of door and window openings, as well as filling voids. Its operating principle is quite simple. Initially it is in a liquid state, but after spraying and due to contact with water and air, polyurethane is formed. Some people also use foam as decoration. Sculptures, figurines and much more are created from it.
According to their characteristics, foams differ in composition, temperature of use, type of packaging, flammability class, scope of application and price. To understand all these details, we turned to the blogger of the construction YouTube channel and master finisher Pavel Sidorik .
What is polyurethane foam and how is it formed?
Polyurethane foam is a foamed polymer that quickly hardens (polymerizes) in air. Release form: metal cylinders of various volumes. The cylinder contains a prepolymer in a liquid state and a propellant gas. Substances called propellant gases are characterized by having a low boiling point. High pressure is created in the cylinder. When the outlet valve opens, the compound is pushed into an area of lower pressure. When released, the propellant gas boils, forming a large number of air bubbles and inflating the foam.
The choice of polyurethane foam depends on the conditions and tasks
Next, in air, the resulting foam polymerizes - it becomes rigid and hard. The curing process requires water, so it is recommended to wet the surfaces before application. Moisture is also taken from the air. Since there is little moisture in frosty air, there are certain compositions for such conditions.
How to clean surfaces?
Chemical agents will help remove sealant from contaminated surfaces:
- Foam cleaners are produced in the same line as sealants and are suitable for both cleaning the gun and cleaning surfaces.
- Solvents – Acetone, White Spirit, Solvent 646 – effectively cope with fresh stains.
- Dimexide - a pharmaceutical product destroys the structure of polyurethane, removing it from various materials.
To soften the dried layer, you can use vegetable oil, water and vinegar. As soon as the sealant layer becomes pliable, it is cleaned off with a spatula or wiped with a rag.
Important! Test the chemical on an inconspicuous area that needs to be cleaned. If the surface is not damaged or changed color, you can safely use the product.
Wooden surfaces that are not coated with paint or varnish can be cleaned with a solvent. The sealant is carefully scraped off the varnished door with a knife and polished with sandpaper. Then the product is re-painted and varnished.
Remove foam from linoleum, laminate and parquet with a sharp object and remove residues with a special cleaner. The product should not contain acetone, otherwise matte marks will remain on the floor covering.
Properties
Do not confuse polyurethane foam with glue. By the way, there is glue in similar containers that also foams. But there is a completely different composition and nothing can be securely glued to the mounting foam. It can support/hold in a certain position, but none has the strength of an adhesive connection. So don't be confused. This is not its area of application.
How to understand which polyurethane foam is better? You need to know its properties
To correctly understand where polyurethane foam can be used, you need to know about its properties. They are very good:
- Mounting property. This is tying, connecting, attaching (not gluing) parts of a structure.
- Soundproofing. Polyurethane foam cannot be called soundproofing, but it reduces the noise level.
- Thermal insulation. Due to the large amount of air enclosed in thin polymer bubbles, thermal conductivity is reduced.
- Good adhesion to almost all building materials. Cannot be used only with silicone, rubber, and some also with polyethylene.
The main use of construction foam is installation. It’s not for nothing that it’s called polyurethane foam. But it is also not bad as insulation and sound insulation. Not perfect, but not bad. Filling seams, cracks, sealing/thermal insulation of communication inputs - this is its area of application. In this it is difficult for her to find competitors. How were such gaps filled in the past? They hammered it with rags and covered it with mortar. Foam in this regard is much more convenient and has better properties.
How to putty foam joints?
Putty is the best option for protecting foamed joints from moisture and ultraviolet radiation.
Primer mixtures are usually used in combination with putty - they are responsible for better adhesion of materials. Work progress:
- After cutting the foam, the seams are thoroughly cleaned of dust and debris.
- A primer is applied to the surface and the composition is allowed to dry - from 6 to 12 hours, depending on the composition.
- Mix the putty according to the instructions and apply the starting layer. The leveling coating must be dense to mask all defects.
- After 20 minutes, apply the finishing layer, trying to achieve a smooth finish.
When the finishing layer is completely dry, it is sanded with fine-grained sandpaper and treated with a primer. Now you can paint the slopes or cover them with wallpaper.
Important Features
Any type of polyurethane foam has two important characteristics - primary and secondary expansion . Primary expansion is how much the mass increases in volume before the end of polymerization. There are foams with both high primary expansion and low ones. Which polyurethane foam is better - with large or small expansion? It’s impossible to say for sure. They are used in different cases. Low expansion foam is good for filling small cavities, as well as for layer-by-layer filling of deep seams, when installing EPS. Large expansion is more beneficial when filling cavities, using as sound insulation, thermal insulation.
To be specific, for installing windows and doors, it is better to take foam with low expansion. Moreover, both primary and secondary. Unfortunately, this is a professional foam, so you will also need a gun.
The left picture is an illustration of a large secondary expansion. Do you see how the primary frame has been torn apart? Well, the difference between foams is in density and “fluidity”
Secondary expansion is an increase in foam volume after completion of the polymerization process. Which polyurethane foam is better for this reason? Definitely the one with the smaller secondary expansion. Why? Because this process is difficult to predict. And the possible consequences are serious - deformation of flexible or moving parts. For example, window frames or door frames may buckle if the foam expands too much. And even the spacers that are installed do not always help.
Why then do we need construction foam with high secondary expansion? It has its own area of application - filling cavities and cracks in rigid and stable materials and structures. For example, in concrete, as a filler with thermal insulating properties between the wall and the brick finish. Foam with higher secondary expansion is cheaper. For large volumes this is important.
Foam output
Another thing you need to pay attention to is the foam output. This is the volume that can come out of the cylinder. It is indicated in liters. Typically, the larger the cylinder, the greater the yield. But not always. With the same cylinder size, the difference in output can be about 20-30%. It can be determined by mass. The heavier the cylinder (weight indicated), the greater the yield will be.
As you can see, identical-looking cylinders contain different amounts of foam
What else is worth knowing is that the actual yield of polyurethane foam is usually less than declared (this is more often the case with household types). To ensure the required volume, it is necessary to accurately select the proportions of the prepolymer and filler gas. And not all brands can boast of this. Here is a list of those who consistently produce the declared volumes:
- Soudal (Soudal) professional lines (not household).
- Penosil (Penosil) Gold (Gold) and Premium (Premium).
- Moment Installation (very inexpensive and widespread).
- Wellfoam (WellFom).
- Hilti (Hilti).
- Kim Tec (Kim Tek).
- Den Braven (Den Braven).
- Illbruck (Illbrook).
- Tytan (Titanium) (some batches either do not work at all or produce less than half of what was declared).
There may be other good brands of construction foam. But these are the ones that, according to builders, very rarely fail. When purchasing, look at the production date . After a year, the valve begins to poison, the filler gas comes out, and the output, accordingly, decreases.
In order for good foam to retain its properties, it must be stored correctly.
Note! You need to work with polyurethane foam, which is at room temperature. In cold weather, you need to pre-warm it. Even winter or all-season.
Level of quality
Professionals regularly test products from various manufacturers to determine the best sealant. When choosing a good product, they primarily focus on the following points:
- The polyurethane foam should adhere perfectly to any surface and not flow from it.
- It does not decrease in size after final drying, that is, it does not shrink significantly.
- High-quality products are characterized by elasticity.
- It does not create cracks in the cold and does not crumble.
- The weight of the cylinder should be on average about 910 grams (taking into account the foaming substance equivalent to 750 ml).
The modern market is actually full of different types of this product, but this does not mean that any polyurethane foam offered by the manufacturer is of high quality. Often, the shelves of construction markets receive products that do not meet the established requirements: for example, in the form of a traditional propellant gas, toxic substances are included in the composition of the foam, which are very harmful to the ozone layer and, of course, to health.
IMPORTANT: there are cases where companies simply underfill MP into the cylinder. Of course, not only the quality of the product suffers from this, but also the consumer himself. Therefore, be careful!
Types and applications
All cylinders with polyurethane foam can be divided by area of application: household and professional. They are also different in appearance. Professional ones are made for a special pistol. It won't be possible to work without it. Household ones have a push valve (as in aerosols) and a long thin tube. Of course, these are not all the differences. There is a difference in properties:
- Curing speed. Professional ones harden faster. Some brands become hard after 30 minutes. “Normal polymerization time” is 24 hours. This is how long it is recommended to wait after applying the foam before continuing work.
- Amount of secondary expansion. For professional ones it is about 30-50% of the primary volume, for household ones it can be 130-250%.
- Dimensions of cavities. Foam consisting of small bubbles is considered good. This is what distinguishes professional ones, although some household ones also have few large cavities. But they are not cheap either.
We decide which polyurethane foam is better based on its characteristics.
Of the entire list, the most unpleasant thing is the large secondary expansion. Why is this bad? Because when foaming windows and door frames, the greatly increasing foam can bend the wood or profiles. Well, because it grows too actively, it is difficult to dose, which leads to large overspending. So the difference in price turns out to be quite insignificant. If it remains at all.
When and where to use these types of polyurethane foam? Household foam is also suitable for filling cavities and holes in rigid structures. For example, Boxer, Ultima, Cosmoflex, Wellfom, Storehouse. When installing doors and windows, it is better to work with a professional. These are Ilbrook, Penosil, Soudal, Titan.
Species by season
Polyurethane foam is also divided according to the temperature conditions of use. There are the following types:
- Summer. Use at temperatures above zero, but not lower than +5°C.
- Winter. It can be used in frosts down to -18°C.
- All-season. Its stated range is from -10°C to +35°C, but it is optimal to use it somewhere in the region from +10°C to zero. At lower temperatures, winter is better, at higher levels, summer is better.
Which polyurethane foam is better: which is suitable for the temperature conditions?
In a heated room, we use summer foam; if we foam windows in winter, we use winter or all-season foam, depending on the temperature outside. In general, the “specialized” one—summer or winter—performs better. They are adapted to certain conditions, and this is always more reliable than a universal option (all-season).
When working in winter, do not leave the foam in the cold. Bring it into a warm place. If it gets too cold, it will be too fluid and won’t hold its shape. In general, we always keep the foam warm. And one more thing - more foam comes out of a warm balloon.
By flammability
Polyurethane foam must also be selected based on flammability. There are three classes:
- flammable - the cylinder is marked B3;
- self-extinguishing (no fire, it does not burn) is marked B2;
- non-flammable (even in fire it retains its properties for a certain period of time) is designated class B1.
Flammable and non-flammable mounting foams.
The degree of flammability is indicated by the letter B and numbers from 1 to 3. B1 - non-flammable, B2 - self-extinguishing, B3 - combustible. In wooden and frame buildings, it is best to use non-flammable construction foam. It should also be used in rooms with increased fire safety requirements. In houses, such a room is a boiler room. Every serious manufacturer has fireproof/non-flammable polyurethane foam. You need to watch it in a professional line. For example, Tytan B1, Soudal FR, Den Braven (Den Braven), Kim-Tec (Kim Tek).
There are also two-component polyurethane foams. But they harden very quickly, so they are used by professionals, and even then not all. You need skill to work, but two-component foam costs a lot.
Special types
There are some types of work that require special properties.
- With increased adhesion to wood. There are different brands, for example, VIK (Vik) professional and household, FOAM 65, AkFix 940.
- Heat resistant. Used for sealing chimney outlets. In general, you can take any with fire resistance class B1. Even if it darkens or turns black, it will not lose its properties. Examples: Penosil Fire Rated B1 (positioned as chimney foam), Tytan Professional B1.
Which polyurethane foam is better? The one with fewer large cavities - Very fast, almost instant polymerization (for example, Soudal 2K). They are used in work at heights, when waiting even 30 minutes is impossible. They are used by industrial climbers during installation and repair work.
- Remain flexible after hardening: AkFix Maximum 65, PROFPUR ELASTICFORCE and others. Such foams are needed in places where there are constant vibrations or tensile loads.
The brands listed are far from the only ones. There are others too. Look at serious manufacturers of construction chemicals, read the characteristics, look for reviews. We are already accustomed to the fact that the stated characteristics do not always coincide with reality.
Do I need to trim dried caulk?
Dried foam spoils the appearance of the installed door, so the resulting sagging is removed after hardening.
This is allowed to be done no earlier than 24 hours after completion of installation. To work, you will need a construction knife with replaceable blades. The sagging is removed so that an even right angle is formed, and the level of the foam is level with the level of the walls.
If putty will be used for further processing of the seams, use a knife to slightly delve into the sealant, cutting off a few millimeters of thickness.
Guns for professional polyurethane foam
If you decide to use professional polyurethane foam, you will need a gun for it. There is a wide range of prices here. But for one-time use, you can take an inexpensive one. The price does not affect the amount of foam. It’s just that the more expensive ones better control the intensity of foam output and deliver it over a greater distance.
Professional polyurethane foam requires a special gun
The ability to adjust the feed intensity is available in any, but the level of control is different. After use, if the cylinder is not empty, it can remain in the gun for 2 weeks or a month. During this period, you can simply continue working. But a “loaded” pistol must be stored in a warm room, not in direct sunlight.
When replacing the cylinder, if the foam flows normally, no additional manipulations are needed. If the foam stops coming out and the container is not yet empty, the nozzle may be clogged. Then the nozzle can be washed. If the liquid comes out without problems, then the problem is in the cylinder. Usually the propellant runs out prematurely, but the copolymer can also run out. After finishing the work, the cylinder is removed, the gun (nozzle) is washed with a solvent (spray foam cleaner). No other manipulations are required.
Is it possible not to use fasteners?
Additional fastenings will not be required if you use only foam and wedges from scrap materials for installation. Pieces of thick cardboard or strong wood chips are suitable for these purposes.
Spacers are installed in the space between the wall and the door block in three places - at the level of the lock, upper and lower hinges. By analogy, wedges are placed on the opposite side of the opening.
The foam is applied in a thin layer on the outside and inside of the room. The spacers are removed from the gaps a day after foaming.
Features of MP
What is polyurethane foam? It is a liquid polymer that hardens after a certain time. In order for this product to have the consistency of foam, the polymer is mixed in a cylinder with a specific gas. MP can be produced in two variations:
- The household or otherwise adaptable variety is a balloon with a tube. Optimal for people who are dealing with construction for the first time. The main advantage of this type is that you do not need to use additional tools to use it.
IMPORTANT: the adapter version accounts for the most low-quality products, since an unscrupulous manufacturer relies on the inexperience of the person purchasing the can with a tube. Often the composition contains excess filler gas, or, on the contrary, there is practically no gas, but there is a lot of polymer.
Among the disadvantages: often the indicated volumes of foam do not correspond to reality. Of the 65 “declared” liters, there are often only 45 in the can. Remember this and keep your receipts.
Related article: The door to the room is closed, how to open it
The best polyurethane foam brands in 2022
This is the selection presented in our rating. Among the brands that truly deserve the respect of users this year are the German DEXX and KRAFTOOL. Despite the fact that the factories are located in different countries (Russia and Switzerland, respectively), the characteristics of foam fillers are at the same high level. The consistent quality and compliance of foam volumes with the declared volumes is demonstrated by Makroflex products from Estonia - the most popular brand on the domestic market. Other brands from the European Union, such as Tytan (Poland) and Soudal (Belgium) are considered the best in their segment of low-temperature and fire-resistant foams, respectively.
The other “echelon” is the products of domestic brands. It is more affordable, and, to be honest, is not much inferior to imported analogues. This is especially true for mounting foams under the Moment and TechnoNIKOL brands - these products raise no complaints either in terms of yield or quality of adhesion. PROFFLEX is characterized by a fairly dense mass that does not change volume when hardening (shrinkage is minimal). IRFIX foams are an affordable analogue of European products for filling openings with high fire safety requirements. The budget segment is also complemented by KUDO products - the cost of this foam is in full accordance with the characteristics and yield of the product.
"Soudal"
Less popular polyurethane foam, but one of the most worthy in the quality category. Several variations of the product are available: for summer and winter, as well as a separate type - fire-resistant. In winter, Soudal operates at a maximum temperature of minus 20°C. Does not contain toxic additives and does not have an unpleasant odor.
Conducts slight secondary expansion and adheres well to the surface. The structure contains a minimum of pores and a maximum of density. Scope of application: sealing and insulation of roofs, installation of various structures, insulation of pipes, plumbing repairs. It does not shrink, hardens instantly and, most importantly, evenly.
Among the disadvantages: “Soudal” does not tolerate ultraviolet light well, so if you do not cover it with protective paint, then after a year it will crumble and take on an unpleasant brown tint. Average cost – 250 rubles.
What compositions are used?
Most foams have the same composition. The main substance is polyurethane foam one-component sealant. Thanks to the aerosol packaging, it is easy to apply to surfaces without getting your hands dirty. The second substance found in the can is the propellant - this is a gas that displaces the polymer we need.
After drying, all types of foam become hard. The excess can be easily cut off with a knife, the foam itself can be puttied and can be finished in any way. Polyurethane foam is used for PVC windows , door frames, filling gaps in various structures, installing window sills, fastening parts made of concrete, wood, and metal. The foam seals cracks well and has a pronounced fixing effect.
Are your new windows not perfect? What to do if plastic windows freeze? This is discussed in detail in our material on the website.
Common brands
The most common and well-established brands of polyurethane foam in the construction market are the following:
- Moment-Montazh;
- Makroflex;
- Soudal.
“Moment installation” is the most common option, produced for domestic and professional use. According to seasonality - usually all-season. It has high adhesive properties. Due to its dense and homogeneous structure, it is most often used when installing metal-plastic structures.
"Makroflex" is also often found in stores. Suitable for use on any surface. Has a low coefficient of secondary expansion. Divided according to seasonal use.
"Soudal" is not often found on sale, but this foam is worth looking for as it has excellent qualities. It is characterized by the absence of toxins and specific odor, good density and low porosity. In addition to winter and summer foam, the manufacturer produces fire-resistant options.
Recommendations for foaming
- Foaming is carried out with smooth, uniform movements from bottom to top or from left to right.
- The gap is not filled completely, but by 30-50%.
- The foam is supplied in small strips, the length of which should not exceed 100 mm.
- The holes are foamed in several layers, each subsequent layer is applied after the previous one has hardened.
- The through holes on one side are covered with sheets of some material, cardboard is suitable, and after hardening they are removed.
- When carrying out work in the cold season, the foam container must be kept in warm water at a temperature of 30-40 degrees.
- The efficient pushing of material out of the container is facilitated by placing the container upside down.
- The optimal temperature for operation is +5…+25 degrees.
"Penosil"
Also not a particularly popular brand, but very high quality. The product is dense and uniform, and practically does not produce secondary expansion or shrinkage. This is a champion among MPs in terms of output volume. Effective for internal work during fixation and installation of structures, excellent in filling cavities and seams. Virtually odorless, white in color.
Among the disadvantages: Penosil is not suitable for outdoor use: it no longer works at -4°C and +35°C. During hot weather, the sealant refuses to foam, so it simply flows out. Average price – 220 rubles.
Related article: How to insulate a wooden balcony door for the winter
"Titan O2"
This is the most respected brand among professionals. Titanium is quite economical, but does not lose quality. It is non-toxic and adheres well to all surfaces. It has a fine and dense structure, holds volume well, and does not shrink or expand. The foam yield is average.
You can choose an acceptable Titan series: for the winter period and products with increased fire resistance. Scope of application: installation of pipes, repair of heating systems and water supply. Experts also recommend using it for thermal insulation.
Among the disadvantages: poor tolerance to ultraviolet radiation, fragility: after a year, Titan begins to crumble, lose elasticity, and darken. However, nothing like this is observed indoors. Average cost – 230 rubles.
"Makroflex"
One of the most popular and famous brands. Plus, it is considered the most economical. It is used for summer and winter use and adheres perfectly to absolutely any building materials. The sealant has a visually homogeneous structure and conducts a minimum of secondary expansion. The declared yield is on average about 25 liters.
The range of applications is quite wide: traditional sealing, excellent heat and sound insulation, installation of door and window frames, plumbing repairs.
However, there are disadvantages. Sometimes among the sealants of this brand there is an outright defect, which also applies to the pistol. In this case, either one polymer comes out of the Makroflex cylinder, smearing everything around it, or only gas, and after the release of a small volume of “foamy” substance, splashes appear.
Another drawback that experts warn about is serious shrinkage. After using low-quality products, you have to cut off the cavities and “add” the lack of volume there. The average cost is 200 rubles. (capacity – 0.75 liters).
