[Baiyun Online] How to Choose Sealant for Doors and Windows

Today, “Baiyun Online” is back again to share insights with you.

Today’s topic:

How to Choose Sealant for Doors and Windows

As channels of connection between indoor and outdoor environments, doors and windows are also the bridges of sunshine, air, and energy exchange, realizing the society’s concept of energy saving and emission reduction in modern life. High-quality doors and windows are essential for a high-quality life.

During the production of manufacturing these essential bridges, sealants, auxiliary materials in petty proportion though they are, play a crucial role in forming their performance, especially in terms of water, air, warm, sound insulation.

If the sealant is of poor quality, it may cause issues such as water and air leakage, which seriously affect the air and water tightness of the doors and windows.

So, what kind of sealant should be used for high-quality doors and windows?

Today’s Baiyun Online will explore this with you.

01 Choose Products with the appropriate Movement Capability

Currently, the main standards for door and window sealants in China include GB/T 14683–2017 “Silicone and Modified Silicone Sealants for Construction” and JC/T 881–2017 “Sealants for Concrete Building Joints”. Both standards refer to ISO 11600 for classification methods and requirements. According to GB/T 14683, sealants are classified based on movement capability into levels of ±50%, ±35%, ±25%, and ±20%. JC/T 881 further includes ±12.5% and ±7.5% levels.

Since door and window joints generally experience only small movement, they do not require sealants with high movement capabilities. Therefore, most sealants on the market are rated at ±12.5% or ±20%. However, high-movement-capability sealants offer better performance of joint movement, so when it comes to applications with larger joint displacement, the use of sealants with high movement ability is recommended as the preferred choice.

02 Choose Excellent Weatherproofing Sealants

Among various types of sealants, silicone-based sealants have the best weather resistance. However, the quality of silicone sealants on the market varies. Some manufacturers significantly reduce the content of silicone base polymer in order to cut costs and instead use large amounts of cheap mineral oils and powder fillers. These are commonly known as “oil-filled sealants,” which pose serious quality risks.

Although such sealants may initially appear to function well, over time, the mineral oil migrates, leading to the sealant’s hardening, chalking, and cracking. If these oil-filled sealants are in contact with insulated glass units (IGUs), the mineral oil can penetrate into the IGU, leading to oil infiltration or “rainbow effects,” ultimately compromising the seal and functionality of the glass unit.

Mineral oils belong to the alkane class of plasticizers.

The national standard GB/T 14683-2017, implemented in 2018, strictly limits the use of alkane plasticizers in silicone sealants. It explicitly states that GW-class products must not contain detectable alkane plasticizers. Therefore, it is recommended to choose GW-class compliant silicone sealants.

To determine whether a sealant is oil-filled, refer to GB/T 31851-2015 “Detection Methods for Alkane Plasticizers in Silicone Structural Sealants”. This standard outlines methods such as thermogravimetric analysis, weight loss on heating, and infrared spectroscopy to quantitatively or qualitatively detect alkanes (mineral oils). While accurate, these methods require advanced lab equipment.

Our company, Baiyun Technology, led the development of the group standard TFSI 088-2022 “Rapid Detection Method for Alkane Plasticizers in Silicone Sealants,” which offers a quick identification method when you are in offices, factories, and construction sites:

Apply the sealant onto a 12-micron thick, smooth PE film and observe after 24 hours.

The principle is simple—mineral oil in the sealant migrates and penetrates the film, causing it to become uneven. The more oil present, the quicker and more obvious the deformation. Non-oil-filled silicone sealants will keep the film flat no matter how long they are left.