Let's look at the question: how long does polyurethane foam dry?

Professional mounting foam TECHNONICOL 65 MAXIMUM all-season 1000 ml. Photo Petrovich

Polyurethane foam has many advantages and positive characteristics, which ensure its popularity. Properties are especially important when selecting and purchasing materials. But some parameters are necessary during the work process .

Assembly seams require final finishing. To do this you need to know how long it takes for polyurethane foam to dry?

Composition and scope of application

Depending on the temperature of use, the material is:

• all-season;
• summer;
• winter.

According to the working mechanism :

• professional cylinders (screwed onto a special release device - a gun);

• household cylinders (equipped with a plastic outlet tube).

There are three flammability groups :

• fire protection - designated B1;
• self-extinguishing – marked B2;
• flammable - designated B3.

The main factor influencing the hardening time is the composition . Based on the active substance, there are two types of sealant:

1. One-component. All household foam sold in cylinders falls under this definition. According to the type of delivery of the substance, it is an aerosol. The container is filled with several components that form a polyurethane sealant, but it becomes that way when it comes into contact with air. Inside, only a partial chemical reaction occurs, forming a fluoropolymer in a liquid state. The foaming agent is a mixture of liquefied gases, united under one name - propellant. The mass leaving the container under pressure upon contact with air expands up to 20–40 times. All the voids encountered along the way are filled. Hardening occurs due to the moisture contained in the air. The chemical reaction stops after a day. The foamed mass becomes a full-fledged solid polyurethane.
2. Two-component. This is a professional sealant. The components of the building material inside the cylinder are not mixed. The connection occurs at the outlet of a special gun. The device resembles a mixer. Hardening is not affected by air humidity. Within 10 minutes after being released from the container, solid polyurethane can be cut with a knife. The expansion coefficient is greater than that of household foam.

The main area of ​​application of polyurethane foam is construction. It is used to fill seams and cracks whose width exceeds 2 cm. The material is in demand when installing windows and doors. Do not foam fatty areas, polyethylene, or items coated with Teflon or silicone. In these cases, polyurethane exhibits poor adhesion.

Polymerization of concrete

Concrete hardening is carried out due to hydration - a special chemical reaction that occurs between binder components and water. The process is intended to convert the base raw material (cement-sand mixture with crushed stone and sand) into calcium hydrosilicate. At the end of the hardening period, a monolithic base with increased strength properties is created.

The hardening time of concrete is determined by the following factors:

1. mixtures.
2. Proportions and ratio of components in the solution.
3. Indicators of atmospheric humidity.
4. Production technology.
5. Ambient temperature.
6. Thickness and density of concrete pouring.
7. Compliance with the rules for caring for the solution during the hardening process.

For complete polymerization, two stages are involved:

1. Grasping.
2. Set of declared strength.

When determining how long concrete takes to dry, it is important to consider the brand of cement that was used when mixing the mixture. The M500 model is characterized by the greatest reliability, and the M100 has the minimum strength.

The hardening time of concrete is determined by the proportions of the components and the presence of various fillers in the composition. The more sand or gravel there is in the solution, the faster the excess liquid will come out of it. If you use a large amount of expanded clay and slag, the water will begin to evaporate more slowly.

To retain moisture in the mixture, it must be covered with a waterproofing film. It can be polyethylene or bitumen mastic. The purpose of such materials is to enhance hydration and protect the solution from rapid loss of liquid.

This effect is also achieved by periodically wetting the solution with water. It is applied by spraying or spraying.

Grasping

Setting of concrete is the first stage of its polymerization and takes no more than 1-2.5 hours. The exact interval is determined by the temperature conditions under which the work is performed:

1. If the ambient temperature is +20°C, the chemical reaction will start 100-120 minutes after pouring the mixture into the formwork. Then the composition will dry for another hour.
2. At a temperature of +1...+19°C, setting will occur in 3-5 hours.
3. At zero temperature, the reaction begins 7-10 hours after mixing. In this case, the drying time will be 16-20 hours.

If there is a negative temperature at the construction site, the components of the mixture will no longer enter into the process of hydration with water, and the mixture will not be able to dry. It will remain inert until temperatures rise above 0°C. To get rid of this phenomenon, you can add special fillers to the concrete composition that accelerate hydration, or build insulated formwork.

If it is hot enough outside (above +30°C), the setting time of the concrete will be reduced, but the quality of the final product will decrease. This is due to the rapid evaporation of moisture and deterioration of the strength properties of concrete products.

During hot periods, special fillers are added to the mixture, which increase the hardening time of concrete.

Among them:

1. Acid NTF.
2. Sugar feed molasses.
3. Sodium gluconate.
4. Complex compositions.
5. Other additives.

How long it takes concrete to dry and how long it takes to set depends on a lot of factors. Hydration refers to the process of converting raw materials into calcium hydrate, i.e. the cement base begins to mineralize and becomes monolithic.

Curing time

After setting, the concrete hardening process begins. It consists in the occurrence of a chemical reaction between cement granules and the liquid from the solution. The best hydration rates are observed at air humidity of 75% and at a temperature of +15...20°C.

If the temperature remains below +10°C, special anti-frost components will need to be added to the composition. Otherwise, the concrete will not receive its design strength.

Features of the material

To judge the drying speed of the sealant, you need to understand its features :

• After leaving the container, the volume immediately increases initially. The sealant fills the entire space down to the smallest cracks.
• When the polyurethane is already exposed to air, secondary expansion occurs. This feature can have a big disadvantage if the conditions of use are not followed. Polyurethane foam reduces volume in case of extreme heat, dirty base or premature mechanical impact.
• The surface layer of household foam hardens in 20 minutes. You can cut off the excess after 4 hours. A two-component sealant hardens faster. The chemical process is completed within a day.
• A feature of the installation material is increased adhesion. Polyurethane adheres well to glass, wood, concrete, plastic, steel, and stone.
• Cured polyurethane does not react to temperature changes.
• The mounting sealant is afraid of UV rays. When exposed to the sun, it turns orange-brown and breaks down.

Polyurethane foam serves only as a sealing material. The hardened polyurethane on top must be protected with putty, paint, and primer.

Adhesion

An important characteristic of a sealant is adhesion, which refers to the ability of the composition to bond to a surface. For high-quality material, this unit of measurement should be high in relation to any building materials. Problems with the connection occur when you need to secure polyethylene or cellophane, or Teflon.

The quality of the connecting material depends on the packaging. Good containers have durable and reliable valves that prevent the atmosphere from entering the container and the excessive release of compressed gas from it. A good quality cylinder has more weight and, if you turn it over, you should feel how the contents move quietly and slowly in it.

Use temperature

The recommended temperature of use influences how long the foam will take to dry. For summer foams, the temperature range is set from +5оСº to +35оСº. Winter sealant can be used in frosts from –10°C. There is foam recommended for use at –18°C. However, the lower the air temperature, the lower the expansion coefficient. All-season is universal and can be used in winter and summer.

Cured polyurethane is not affected by ambient temperature.

Specifications

As mentioned above, various types of work are performed with the help of polyurethane, this not only applies to the installation of windows and doors, this building material is used to seal dimensional cracks, fill voids and fix structures. If you familiarize yourself in detail with all its positive properties, you can conclude that it can be compared with other sealing substances due to its ability to qualitatively seal the desired surfaces.

Before considering the issue of drying time for polyurethane foam, it is recommended that you familiarize yourself with the characteristics of the indispensable construction sealant, its properties and features.

Output volume

This indicator demonstrates how the material has changed compared to its original state. This volume is measured in liters. The main aspects influencing this indicator are the air temperature and humidity of the structure being finished.

Surface adhesion

This parameter helps determine the quality of adhesion of the material to the coating. The exception applies only to surfaces such as grease coatings, polyethylene, silicone, Teflon, etc.

Viscosity coefficient

This indicator will depend largely on the quality and quantity of components used to make the material. This characteristic is also influenced by external factors - temperature. It is recommended to work with the substance according to the instructions, which indicate the exact data and permissible air temperatures.

If you use the sealant outside the specified limits, it will lose its basic properties, and the initial product will not meet all the requirements.

Expansion coefficient

When looking for a good installation sealant, you need to consider not only how long it takes to dry, but how much it expands. The consumption of material and the quality of foaming will depend on this indicator. Household foam can expand up to 60% in air. Professional sealants increase volume up to 300%.

The expansion coefficient depends not only on the composition. The increase in volume is affected by air temperature, humidity, and the rate of release of the initial composition from the cylinder. Even the method of foaming affects expansion: through a tube or a gun.

The volume of foam after expansion is written on each cylinder, but in reality this indicator does not match. The data is given for ideal conditions, which cannot be created at a construction site. The primary expansion immediately after exiting the balloon is considered primary. The polyurethane will further increase its volume up to 30% until the chemical reaction stops after 24 hours. However, during secondary expansion, shrinkage occurs, the rate of which for high-quality installation material does not exceed 5%.

Requirements

Polyurethane foam is a material that, like any other, has a number of requirements.

These requirements include:

• good surface bonding;
• elasticity;
• after hardening, the material should not crumble, even when exposed to sub-zero temperatures;
• The shrinkage of the solution, which has already dried, should be moderate.

We draw the attention of users to the fact that the foam is very resistant to direct sunlight. For this reason, after complete hardening, the excess is cut off, and all compacted areas are treated with paint or plaster.

And in order not to disturb the density of the material and to do the application sequence correctly, you need to know how much time is needed for complete hardening.

To eliminate gaps between door frames and openings, you will need only a third of the sealing compound. The material will begin to harden on the surface within half an hour after application. You may notice that a film will appear on the surface.

Final drying can be expected 8 hours after the material is applied. The fixing process occurs due to the expansion of the substance, which leaves the container and hardens.

Conventionally, this is divided into several stages:

• primary, which is carried out immediately at the exit from the package;
• secondary, which is not completed until the final transformation of the foam into a solid composition.

If the material is of high quality, then at the second stage the expansion rate can reach 30%; this must be taken into account during the work process. Most often, a third of the material is spent filling the space; this is enough to fill all the cracks during expansion.

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How to choose polyurethane foam?

It is impossible to determine which polyurethane foam is best for doors, windows or other purposes. The following points are taken into account:

• The size of the space to be filled . It is better to foam narrow cracks with an assembly sealant with a low expansion coefficient. To fill a large space, a significant increase in volume plus increased strength is important.
• Best before date. Typically, the manufacturer limits the use of polyurethane foam to 18 months. However, with increasing storage, even if the expiration date has not yet expired, the liquid composition acquires viscosity inside the container. The result will be much less than the declared volume, but after hardening the polyurethane will be denser with small pores. Due to long-term storage, the composition inside the cylinder tends to diverge. Before use, shake it well for about 30 seconds to mix all the ingredients.
• Household or professional. One-time foaming is easier and cheaper to carry out using a household cylinder with a straw. If there is a lot of work to be done, it is better to buy a pistol. The additional costs will be justified by the savings in installation material, which will be approximately doubled. Professional sealant is used by window and door installers.
• Cylinder weight. When purchasing, an ordinary person thinks that the heavier the container, the more polyurethane foam will come out. This is wrong. As the liquid composition increases, the amount of injected gas decreases. The sealant just won't come out all the way from the container. The light weight of the container means more gas, but the amount of foam may not be enough to foam. Conscientious manufacturers maintain an optimal balance. A cylinder with 750 ml of liquid composition is pumped with 250 ml of gas.

When choosing a sealant, be sure to take into account at what air temperature it will be used.

It is impossible to make polyurethane foam at home, although this question worries all enthusiasts. The technical process is very complex and dangerous. An alternative can be liquid foam, but its manufacture requires the purchase of special equipment. It’s easier to buy a ready-made container of foam.

Sealing joints indoors

To implement this construction task, it is necessary to use the same technologies. To achieve optimal results, you can use aesthetically pleasing drywall. This material will hide foam seams from prying eyes, and small slabs can be protected with emulsion or covered with wallpaper.

There is only one drawback - drywall is susceptible to high humidity, which is why it is not intended for the street side of the building. The material can be easily attached to the surface using standard size dowels and self-tapping screws. A craftsman can create a truly ideal surface with his own hands at an affordable price. Once the panels are in place, they should be coated with a quality primer for optimal adhesion to the upcoming finish.

To install drywall, you need to build a durable profile made of natural wood. If the walls are smooth, then you can get by with classic lathing. In this situation, the panels are simply placed on a special glue, which greatly simplifies and speeds up installation. Thanks to this, during many years of use, users will not encounter various unpleasant moments.

Otherwise, leaks, drafts, the growth of ice crusts, as well as uncontrolled growth of mold on those surfaces adjacent to the frame and wall opening cannot be ruled out. The standard service life of a foam joint is 17 years if all construction procedures were carried out correctly. But the final figure depends on the factory, operating conditions, as well as the degree of compliance of the completed construction work with established standards.

Using putty inside the house

How long does it take for polyurethane foam to dry?

It is impossible to determine exactly how long it will take for Makroflex polyurethane foam or another manufacturer to dry . It all depends on the conditions of use. The polymerization process is affected by water. At normal humidity, a layer of sealant 5 cm thick will harden in 3 hours. The excess can be cut off, painted over or plaster applied. Final polymerization will occur after 12 hours. In frost or dry air, hardening lasts a day. Don't rush to cut off the excess ahead of time.

Many people wonder why, when specialists install doors or windows, the foam dries quickly. The secret is in the water. Before foaming, the gaps between the frame and the wall are wetted. Moisture accelerates the polymerization process

How to use the product?

Before using sealant, you need to correctly calculate its volume. If you need to foam the door with polyurethane foam, then the gaps between the frame and the wall 3–5 cm wide will be filled from a 300 ml cylinder. The output will be about 30 liters of expanded polyurethane. A 500 ml container will produce 35 to 40 liters of foam. This is enough for one and a half door frames. A 750 ml container is capable of dispensing from 45 to 50 liters of sealant. Enough foam to handle two doors.

Before foaming, the surface is cleaned of dust and grease and moistened generously with water. In winter, ice, snow, and frost are removed. To increase the foam yield, shake the container for 30 seconds and warm it to room temperature, but not over the fire.

To properly foam with polyurethane foam, the container is held upside down. In the reverse position, only gas will come out. When using a gun, the cylinder is screwed onto the seat. Extrusion occurs by pressing the trigger. If household foam is used, a plastic tube with handles for pressing is screwed onto the spout of the balloon.

The seams are foamed from bottom to top. They try to apply a uniform layer with a thickness of half the free space. Crevices with a depth of more than 5 cm are filled in twice, allowing time for the first layer to dry.

At the end of the work, the gun is washed with a special solvent. The cylinder is disposed of. After drying, the excess that appears is cut off with a knife.

Consumption

Professional fireproof mounting foam KRAFTOOL Kraftflex Premium B1 750 ml. Stroylandia Photos

Polyurethane foam is available in cylinders of various sizes. Productivity varies depending on the volume. Cylinder with a capacity of 300 ml. gives approximately 30 liters, which is enough to install one door, 500 ml. — 40-45 ml., for installation of two windows, 750 ml. — 50-55 l. for two door frames. But it is necessary to understand that this amount of foam may not be possible, since ideal working conditions practically do not exist. Indicators also depend on the method of presenting the composition, the skill level of the performer, etc. Therefore, there are formulas for calculating consumption. For rectangular seams this is -

P = W x D, where:

• P - flow rate, ml/1 m.p. seam;
• W—seam width, mm;
• Г—seam depth, mm.

For triangular ones - P = 0.5 x W x D.

Obtaining more accurate calculations is facilitated by the use of online calculators, which allow you to find out the number of cylinders or material consumption in meters.

Precautionary measures

The cylinder is filled with gas that comes out along with the polyurethane. Additionally, butane and carbon dioxide are released during polymerization. Work must be carried out in a ventilated area.

Gas is flammable. The presence of open sources of fire is unacceptable. It is prohibited to heat cylinders with burners or throw them into a fire.

Work is performed only in special clothing. Sticky foam is difficult and painful to remove from the body. Be sure to cover objects located near the work. Adhered foam is removed with special solvents or folk remedies are used: vegetable oil, Dimexide, salt solution.

After foaming, do not rush to cut off the cap. If you have extra time, it is better to wait. It is not possible to accurately determine the final polymerization period. Premature removal of excess will ruin the entire job.