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Bulging? How to deal with it

October 30, 2022

    First of all, Most of the construction silicone weather-resistant sealants on the market are one-component sealants, which need to react with moisture in the air during curing, so the temperature and humidity of the environment have a certain impact on their curing speed. usually:

The higher the temperature, the faster the curing speed;

The higher the humidity, the faster the cure.

    Bulging generally occurs when the ambient relative humidity or temperature is low. Because the sealant cures at a slower rate, it will take longer for the sealant surface to cure to a sufficient depth. Before the sealant surface has cured to a sufficient depth, if the width of the sealant gap changes (this is usually due to the thermal The surface of the sealant seam will be affected and unevenness will appear.

After these uneven surfaces are finally cured, the interior is solid, not hollow (the hollow is "bulges"), so we collectively call it "bulging phenomenon".

So, how to construct it correctly?

    The general idea of ​​reducing or solving the bulging phenomenon is two aspects: one is to speed up the curing speed of the sealant; the other is to reduce the deformation of the sealant seam at the initial stage of curing. Therefore, we have the following four construction recommendations:

Selecting relatively fast curing sealants, such as BAIYUN's SS811 and SS511B, can solve some of the bulging problems.

Do not use mineral oil filled weathering sealants for this option. Because the oil-filled adhesive shrinks significantly during the curing process, although the bulging phenomenon will be reduced to a certain extent, this type of product does not meet the national standard requirements for weather-resistant sealants, nor does it meet the requirements for curtain wall applications. Its weather resistance is poor, and the service life is not guaranteed.

    However, if the relative deformation of the sealant seam (absolute deformation / sealant seam width) caused by low humidity or temperature difference, sealant seam size, etc. is too large, the products on the market today cannot eliminate this bulging phenomenon.

Construction suggestion two:

When the panel temperature difference is small and the joint deformation is small, the bulging problem can be solved.

If the next day is cloudy, hurry up and work on that day. Because there is no sunlight, the temperature difference of the panel is small, the deformation of the sealant seam is small, and the bulging phenomenon is not easy to occur.

If the next day is sunny, take appropriate shading measures, such as shielding with dust nets on scaffolding, so that the panels are not directly exposed to sunlight, reduce the temperature of the panels, and reduce joint deformation caused by temperature differences.

Construction suggestion three:

    Applying sealant when the plate expands and the sealant gap is narrow can improve the bulging phenomenon. It is recommended to choose a suitable time for gluing, such as construction when the panels of the facade are exposed to sunlight.

Construction suggestion four:

    Use the second sealant method! First make a concave sealant seam, wait for it to cure for 2~3 days, and after it becomes elastic, put a layer of sealant on its surface. It is recommended to repair the bulging sealant seam that is easily visible to the human eye; It is not recommended to re-sealant after tapping on the bulging sealant seam, which will not only cause waste, but also cannot solve the bulging problem.

    Bulging is not scary, as long as we deal with it scientifically, we can minimize the occurrence of bulging.