The Reason Why Silicone Sealant Cracking And Curing Slow | Shuode

October 12, 2022

The main function of silicone weatherproof sealant is to ensure the air tightness and water tightness of the curtain wall; It is also divided into one component, two components, acid curing glue, neutral curing glue. Now entering winter, climate change, humidity reduction, may reduce the effect of weatherproof glue, resulting in curtain wall leakage and water leakage affect the normal use, construction, mostly choose one component silicone glue.

Curing Slow

Silicone glue in the process of curing with water molecules is from the surface to the inside gradually, but into autumn and winter, the temperature and humidity of the environment has a significant impact on the curing speed, the antisticking of sealant, surface dry and deep curing will be slowed down. In addition, the sealant products on the market are divided into summer formula and winter formula, different formula, curing time is significantly different, in the purchase process according to their own construction environment requirements pay attention to the distinction.

Under standard conditions (temperature (23±2)℃, relative humidity (50±5)%), the surface dry time of one-component silicone sealant in 3 hours, disadhesive time in 24 hours. Under low temperature conditions in winter, the surface drying time and antisticking time will be more obvious.


In the case of low humidity, temperature, silicone adhesive curing at a slower pace, when haven't completely curing plate sharp contractions or deformation will have a bigger stretch on sealant, easy to cause the surface cracking of sealant, deformation, when the plate for a likely is the main type of sealant displacement capacity can't meet the requirements of the deformation of plate glue line.

There is also a situation that the joint itself aluminum plate size error or installation error is too large, resulting in large size deviation, the actual joint size is much smaller than the design size, the actual demand for sealant displacement capacity is higher, and even lead to high displacement level sealant can not meet the requirements of sealant deformation.


If the construction is still used to meet the displacement capacity of the original design joint weatherproof sealant, it will not be able to meet the deformation requirements of the plate. This is similar to the first case mentioned above, sooner or later the problem of cracking joints will appear. And in winter construction, plate deformation is larger, may appear cracking in the early stage of sealant curing.


As a joint with silicone sealant according to the standard of 20HM, 20LM, 25HM, 25LM and other models, different models of silicone sealant in practice have different displacement.

Insufficient cleanliness of the substrate

Silicone sealant vulcanized due to insufficient surface cleanliness caused by low bonding strength, displacement deformation due to poor bonding strength from the surface cracking.

Therefore, the weatherproof sealant must be selected to meet the requirements of joint deformation sealant, sealant size after the actual installation must also meet the design requirements, to ensure that the sealant curing plate can not produce too much deformation, in order to avoid the risk of cracking.

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