The reasons for the foaming of quality SILICONE STRUCTURAL SEALANT in construction are various and complex. It is difficult to determine the cause of foaming with one method and one result. During our construction, we often find the foaming phenomenon of quality SILICONE STRUCTURAL SEALANT. The main reasons for the foaming phenomenon of quality SILICONE STRUCTURAL SEALANT are as follows:

One.The reasons for the varieties of quality SILICONE STRUCTURAL SEALANT manufacturers are that many brands of SILICONE STRUCTURAL SEALANT have experienced similar foaming phenomenon, which is not a quality problem after careful testing and repeated supply. Methanol contained in silicone structural sealant during curing will release gas (methanol begins to volatilize at about 50 ℃), especially in case of direct sunlight and strong high temperature reaction. The metal window frames of concrete are difficult to breathe. In addition, due to the high temperature and humidity in summer, the curing will be faster. The gas released by quality SILICONE STRUCTURAL SEALANT can only run out of the adhesive layer that has never been fully cured, and bubbles of different sizes will appear on the cured silicone structural sealant. In the construction process, we should choose different types of quality SILICONE STRUCTURAL SEALANT according to different conditions.

Two.Construction reasons 
1. Air is wrapped in the glue injection. The quality SILICONE STRUCTURAL SEALANT is generally injected at the construction site, and the operating conditions are poor. The worker stands on the scaffold and injects glue. The uniformity of glue injection is not easy to grasp, and air is easy to be trapped in the glue joint. After gluing, the surface of the sealant is scraped and pressed, and the finish is smooth. The pads in the glue seams are usually closed with polyethylene foam rods. The air in the glue seams is not easy to overflow. After the air is compressed, the air is compressed, and the outward tension is produced. The sealant seams are generally wider and the thickness is relatively small. The weatherproof glue with high displacement capability is low, and the quality SILICONE STRUCTURAL SEALANT is soft before being solidified. The bulge tension of compressed air wrapped in the glue seam is not easy to blister the glue. Therefore, the more weatherproof glue that can provide high displacement ability, the more attention should be paid to the uniformity of glue injection. Generally, the glue can be applied from bottom to top in the vertical glue joint, which can overcome some foaming phenomena. More importantly, the operator's proficiency and sense of responsibility. 
2. Workers are used to glue injection. During glue injection construction, we often find that many workers like to spray with soapy water, detergent water, washing powder water, etc

At the joint of quality SILICONE STRUCTURAL SEALANT, then use hand to smooth it to ensure that the glue does not stick to the hands. But the water flowing down is absorbed by the foam strip. The water is dry. As long as there is soap, detergent and washing powder on the foam strip, the glue will bubble when the glue is applied in the sun.

Three.quality SILICONE STRUCTURAL SEALANT external construction conditions.
1, wet conditions in outdoor operations, often encountered rainfall, if the rain is wet, dry interface directly glue, such as solar radiation bonded substrate and glue joints when the temperature inside the interface, the glue seam gas evaporation, will not solidify, relatively soft glue blisters, sometimes polyethylene foam pad wet will also cause glue seams blistering. Therefore, do not blindly seek progress during construction. Wait until the interface is dry and then inject glue to avoid the above situation.
 2. Under the condition of sun exposure, silicone structural sealant cannot be exposed to the sun before curing, especially when it is exposed to the sun just after the glue injection, which will cause honeycomb bubbles inside the glue joint, resulting in the bulge outside the glue joint. It is difficult to overcome this situation during construction in hot summer. Avoid the sun exposure when using glue injection, which will overcome some foaming phenomena. 
3. The surface temperature of the substrate is too high. When the quality SILICONE STRUCTURAL SEALANT is cured, the temperature of the bonding material shall not exceed 50 ℃. This conclusion has been recognized by most SILICONE STRUCTURAL SEALANT manufacturers. When the surface temperature of the substrate exceeds 50 ℃, the glue injection will cause blistering of the glue joint. The above situation will be encountered when the weather resistant caulking of the metal plate curtain wall. In hot summer, when the sun is exposed to the metal plate, especially the surface temperature of aluminum plate will reach 80 ℃, at this time, glue injection is very easy to cause blistering of glue joint. Therefore, we should choose to inject glue in the second half of the afternoon or cloudy days to improve the above situation.