As we all know, the service life of buildings is generally at least 50 years, so the materials required to be used must also have a long service life. Silicone sealant has been widely used in the field of building waterproof sealing because of its excellent resistance to high and low temperature, excellent weather aging resistance and good bonding properties. However, after the construction of a period of time, the problem of silicone sealant discoloration emerged, giving the building an abrupt "line".


Incompatibility of different sealant materials
Acid sealant, neutral alcohol sealant, neutral oxime-type sealant three can not be used together, they will affect each other and change color, acid glass glue will cause oxime-type glue yellow, neutral oxime-type and neutral alcohol type glass glue used together will also yellow.


Contact with materials such as rubber
Silicon sealant and most rubber (natural rubber, neoprene rubber, three no ethylene propylene rubber) direct contact will turn yellow, these rubber in the curtain wall and doors and Windows are widely used (rubber strips, rubber pads, etc.), this kind of discoloration is characterized by non-uniformity, and rubber directly discoloration, other parts do not discoloration.


The sealant was overstretched and discolored
This phenomenon is easily mistaken for the loss of sealant color, and there are three common causes of such discoloration.


1) Over-displacement capacity with glue, joint displacement is too large, sealant is over-stretched;


2) The local thickness of the sealant is too thin, resulting in the discoloration of the sealant concentrated in the thin part;


Sealant is affected by environmental factors
This kind of discoloration occurs in neutral oxime-type sealant, the main reason for discoloration is that the air contains acidic substances, acidic substances in the air from many sources, such as curing acid silicon sealant, acrylic paint in construction, sulfur dioxide in the atmosphere, nearby burning plastic waste, burning asphalt and so on. These acidic substances in the air can cause oxime sealant discoloration.