In recent years, there have been more and more extreme weather around the world, which has also tested our sealant industry, especially for Chinese factories like us that export to all parts of the world.
In the past few weeks in China, continuous rainfall and high temperatures have left no room for respite. So how to correctly apply sealants in a high temperature and high humidity environment?
1 Packaging and storage of sealants
Since sealants are chemical products, the curing mechanism is to react and solidify when encountering moisture. When soaked in water, the outer packaging of sealants can only play a limited barrier role. Therefore, in summer, sealants should be stored in a relatively high-lying, ventilated and cool place to prevent the sealants from being soaked in rain or even soaked in water caused by extreme weather, which will affect the shelf life of the product and cause curing problems in the product packaging.
The sealants soaked in water should be moved away from the soaking environment as soon as possible and transferred to a dry and ventilated room. The outer packaging carton should be removed, the surface should be wiped dry and placed indoors for use as soon as possible.
2 Correct method of sealant application
Before application, please pay attention to the following:
The ambient temperature requirement for Siway brand silicone sealant products is: 4℃～40℃, clean environment with relative humidity of 40%～80%.
In environments other than the above temperature and humidity requirements, users are not recommended to apply sealant.
In summer, the outdoor temperature is high, especially for aluminum curtain walls, where the temperature is even higher. If the ambient temperature and humidity are not within the recommended range, it is recommended to conduct a small area of sealant application test on site, and conduct a peeling adhesion test to confirm that the adhesion is good and there are no adverse phenomena before using it on a large area.
During application, please follow the steps below:
Construction sequence of structural sealant (structural sealant for curtain walls, two-layer structural sealant for hollows, etc.):
1）Clean the substrate
The temperature is high in summer, and the cleaning solvent is easy to volatilize. Pay attention to the impact on the cleaning effect.
2） Apply primer (if necessary)
In summer, the temperature and humidity are high, and the primer is easy to hydrolyze and lose its activity in the air. Pay attention to injecting the glue as soon as possible after applying the primer. At the same time, it should be noted that when taking the primer, the number of times and time the primer contacts the air should be reduced as much as possible. It is best to use a small turnover bottle for packaging.
3） Sealant injection
After the glue injection, the weather-resistant sealant cannot be applied immediately on the outside, otherwise, the curing speed of the structural sealant will be seriously reduced.
4） Trimming
After the glue injection is completed, trimming should be carried out immediately, which is conducive to the contact between the sealant and the side of the interface.
5） Recording and marking
After the above process is completed, record and mark in time.
6） Maintenance
The unit must be cured for a sufficient time under static and unstressed conditions to ensure that the structural sealant has sufficient adhesion.
Construction sequence of weather-resistant sealant and door and window sealant:
1） Sealant joint preparation
The foam rod in contact with the sealant should be kept intact. The temperature is high in summer, and if the foam rod is damaged, it is easy to cause blistering; at the same time, attention should be paid to the compatibility of the substrate and the sealant.
2） Clean the substrate
The glue joint should be cleaned in place to remove dust, oil, etc.
3） Apply primer (if necessary)
First, make sure that the surface of the glue joint substrate is completely dry. In summer, the temperature and humidity are high, and the primer is easily hydrolyzed in the air and loses its activity. It should be noted that the glue should be injected as soon as possible after the primer is applied. At the same time, it should be noted that when taking the primer, the number and time of contact with the air should be reduced as much as possible. It is best to use a small turnover bottle for packaging.
4） Sealant injection
There are more thunderstorms in summer. Note that after the rain, the glue joint must be completely dry before injecting glue.
5） Finishing
The temperature in summer is higher, and the finishing time is shorter than in other seasons. After the glue injection is completed, the finishing should be carried out immediately.
6） Maintenance
In the early stage of maintenance, there should be no large displacement.
Common problems, How to deal with them:
1. Short break time of two-component structural sealant
Judgment: Break time is shorter than the lower limit of the break time interval recommended by the manufacturer.
Reason: High temperature and humidity in summer shorten the break time.
Solution: Adjust the ratio of components A and B within the range recommended by the manufacturer.
2. Ineffectiveness of structural sealant primer
Reason: High temperature and humidity in summer, improper use of primer can easily lose its activity. Ineffective primer will lead to poor bonding of structural sealant.
Solution: It is best to use small bottles for primer. It is not recommended to use unused primer in the sub-bottle overnight. At the same time, it should be noted that when taking the primer, the number and time of contact between the primer and the air should be reduced as much as possible. And check the status of the primer in the sub-bottle in time. If the appearance has changed due to prolonged storage time, the primer in the sub-bottle should not be used.
3. Weathering sealant/door and window sealant bubbling
Judgment method: There are local bulges on the surface of silicone sealant. When the cured strip is cut open, the inside is hollow.
Reason ①: The surface of the foam stick is punctured during the filling process, and the air is released from the hole after being squeezed;
Solution: The side of the foam stick in contact with the sealant remains intact. If it is difficult to fill, you can cut a part of the back of the foam stick.
Reason ②: Some substrates react with sealants;
Solution: Pay attention to the compatibility of different types of sealants and substrates, and compatibility tests are required.
Reason ③: Bubbling caused by thermal expansion of gas in the sealed glue joint;
The specific reason may be that in the entire closed glue joint, the air sealed in the glue joint after injection expands in volume when the temperature is high (generally above 15°C), causing bubbling on the surface of the sealant that has not yet solidified.
Solution: Avoid complete sealing as much as possible. If necessary, leave a small section of vent holes and fill them after the sealant solidifies.
Reason ④: The interface or accessory material is damp;
Solution: Do not construct on rainy days, wait until the weather is clear and the glue joint is dry.
Reason ⑤: Construction under high temperature conditions outdoors;
Solution: Suspend construction under high temperature conditions outdoors and wait until the temperature drops before construction.
4. Short repair time of weather-resistant sealant/door and window sealant
Reason: The temperature and humidity are high in summer, and the pulling time is shortened.
Solution: Repair in time after injection.
Be careful during construction and follow the instructions to ensure quality.
High temperature and heavy rain are great challenges, and there are tricks for sealant construction.
Deal with problems in a timely manner to ensure the safety of the project.
SIWAY accompanies you through the hot summer and empowers beauty together!
Post time: Jul-10-2024