Curing characteristics of sealant
The curing characteristics of single component sealant: it absorbs moisture from the air and gradually solidifies from the surface to the inside, with faster surface drying and slower deep curing. The deeper the adhesive seam, the longer it takes for complete curing. The curing speed is easily affected by the temperature and humidity of the environment. When the ambient temperature is low, the surface drying time and deep curing speed will slow down. When the ambient humidity is low, the deep curing speed will slow down.
The curing characteristics of two-component sealant: It is cured by the reaction of component A and component B, and the surface and interior are cured simultaneously. The complete curing time is almost not affected by the size of the adhesive joint. The curing speed is less affected by environmental humidity and more affected by temperature. The lower the temperature, the slower the curing speed. Meanwhile, the curing speed can also be adjusted by the amount of component B. The smaller the amount of component B, the slower the curing speed, while the larger the amount of component B, the faster the curing speed. However, the adjustment range of the dosage of component B should be strictly controlled within ± 20% of the specified dosage. If the dosage of component B is too high, it will cause the cured sealant to become brittle and lose elasticity, while if the dosage of component B is too low, the sealant cannot be completely cured.

Construction suggestion: Users should follow the recommended usage environment requirements in the construction process of silicone weather resistant sealant manufacturers for construction; The environmental requirements for the use of silicone weather resistant sealant products are: a clean environment with a temperature of 4 ℃ to 40 ℃ and a relative humidity of 40% to 80%. It is not recommended for users to apply sealant in environments outside of the above temperature and humidity requirements; Construction cannot be carried out outdoors during rain or snow. It should be noted that there may be differences in the construction environment requirements among different manufacturers, and confirmation should be made before construction.
Common Problems in Winter Construction
Winter construction, with low temperature and humidity, can affect the curing and bonding speed of silicone sealant, which may lead to problems during the construction process. Common issues include:
1. Slow curing of sealant
The first problem with silicone sealing tape caused by a sudden drop in ambient temperature is that it feels slow to cure during application. The curing process of silicone sealant is a chemical reaction process, and changes in environmental temperature have a significant impact on the curing speed; The higher the temperature, the faster the curing speed; the lower the temperature, the slower the curing speed. In general, after winter, when the temperature drops below 15 ℃, whether it is a single component sealant or a two-component sealant, the surface drying time and deep curing speed will significantly slow down. At low temperatures, it is necessary to extend the curing time of silicone adhesive. It can dry in just one or two days in summer, and may take three days or even longer in winter.
In addition, many places experience dry and cold weather in winter, with low temperatures and relative humidity. The deep curing of single component silicone sealant requires moisture from the air to penetrate into the interior of the sealant, so humidity also has a significant impact on single component silicone sealant. When the moisture in the air is low and the relative humidity is below 40%, the deep curing of single component silicone adhesive will significantly slow down.

2. Poor adhesion of sealant
As the temperature decreases, the bonding activity between the silicone adhesive and the substrate interface decreases, requiring a longer curing period for the silicone adhesive to achieve satisfactory adhesion.
When the temperature is too low, the sealant will become more viscous and the wettability with the substrate surface will decrease, which is not conducive to the spread and penetration of the sealant on the substrate surface, and will also affect the adhesion between the sealant and the substrate.
When the temperature is too low, there may be imperceptible fog or frost on the surface of the substrate, which can also affect the adhesion between the sealant and the substrate. Before applying sealant, it is necessary to fully confirm that the surface of the substrate is dry before construction.
3. Thickening of sealant
Polymer materials all have the characteristic of viscosity temperature coefficient. As the temperature decreases, the sealant will gradually thicken and the flowability will decrease. For two-component sealant, thickening the sealant will increase the pressure of the glue dispenser and reduce the extrusion of the sealant. For single component sealant, the thickening of the sealant increases the pressure of the glue gun to squeeze out the sealant, and manual operation may feel time-consuming and laborious. If there is no impact on construction efficiency, low-temperature thickening is a normal phenomenon.

4. Weather resistant sealant bulges and wrinkles - uneven appearance
Under low temperature and humidity conditions in winter, the curing speed of silicone sealant is much slower than normal, and at the same time, there is often a large temperature difference between day and night. Taking the application of aluminum curtain walls with a common high coefficient of linear expansion and significant deformation with temperature as an example, the curing speed slows down, and the time required for the surface to cure to a sufficient depth will be longer. When the sealant has not yet cured to a sufficient depth, it encounters changes in the width of the joint, such as excessive temperature difference, panel thermal expansion and contraction, and manual movement or handling causing the plate to be squeezed or stretched. The surface of the joint will be affected, resulting in uneven appearance such as bulging or wrinkles. After the final curing, these uneven surface joints are solid instead of hollow inside, which will not affect the sealing performance of the weather resistant sealant, but only affect the flatness of the joint appearance.

Suggestions for using sealant in winter
1. Choose adhesive with relatively fast curing speed.
2. Improve construction conditions, such as using equipment such as air conditioning and humidifiers to increase the temperature and humidity of the environment and improve the curing speed of silicone adhesive in factories with conditions.
3. For the construction of two-component sealant, the mixing ratio should be adjusted appropriately. During the injection process, attention should be paid to the uniform mixing of components A and B, and within the recommended mixing ratio range by the manufacturer. This can be confirmed through butterfly test and tensile test respectively.
After the on-site panel production is completed, attention should be paid to the maintenance temperature, humidity, and maintenance time. When the maintenance temperature and humidity are low, the maintenance time may need to be extended. The final step should be based on the rubber cutting test to fully determine the curing time of the finished individual components.
5. If the relative deformation of the adhesive joint is too large due to low humidity or temperature difference, adhesive joint size, etc., it is recommended to use one or more of the following methods for construction:
a) On cloudy days, the temperature difference between day and night is small, and the deformation of the adhesive seam is small, which can reduce the phenomenon of bulging and wrinkling on the surface of the adhesive strip.
b) Take appropriate shading measures, such as using dust-proof nets to cover the scaffolding, so that the panels are not directly exposed to sunlight, reducing the temperature of the panels and minimizing joint deformation caused by temperature differences.
c) Do not work on surfaces directly exposed to sunlight for the time being.
d) The method of secondary gluing can be used (i.e. first gluing the concave adhesive seam, allowing it to cure for 2-3 days and become elastic, and then applying a layer of glue on its surface).
6. If construction must be carried out under low temperature conditions, it is recommended to conduct a small-scale adhesive test and a peel adhesion test before use to confirm that the sealant can cure, bond well, and have no appearance problems before large-scale use.
a) When the temperature is lower than the minimum construction temperature of the sealant by 10 ℃, the adhesive properties of the sealant adhesive substrate should be tested in the actual low-temperature construction environment, and the recommended method for adhesive properties testing should be strictly followed during construction. Confirm good bonding before construction.
b) There are many batches of materials used during the construction process (aluminum, glass, sealant, cleaning agents, primer, etc.), and it should be noted that there may be differences between different batches. During the production process, each batch of materials entering the factory needs to undergo random on-site adhesion tests.
c) If a primer is required, during the construction process, the cleaning or coating method should comply with the construction process. After the cleaning solvent evaporates, the primer should be applied in a timely manner; The primer should be thin and even, and attention should be paid to the connection of the next process. It is best to apply the adhesive within half an hour after the primer is dry.