Glasses Fogging Up? Uncover 3 Powerful Ways for Clear Views

As modern home decoration has improved, many people have chosen aluminium doors and windows in recent years. However, some have noticed that the glass on their doors and windows is becoming foggy and blurry despite enjoying a quiet, comfortable home. What could be causing this?

The fogging problem that occurs in insulating glass is caused by an unqualified production process. We must first understand the insulating glass production process to understand why this happens and how to fix it. This blog will give you some insight and explain it.

Insulated Glass

How is insulating glass made?

The production process of insulating glass involves several steps, such as cleaning the glass, filling it with molecular sieve, applying butyl sealant, closing the sheets, and finally applying a second sealant. The quality of materials used and the operator’s proficiency are crucial factors affecting the production process at each step.

glasses fogging up

First: Glass Cleaning

The initial step in insulating glass production is to clean the glass, which is also one of the most crucial stages to ensure the sealing of insulating glass. If the oil and sweat residue on the glass is not cleaned off thoroughly, it may considerably weaken the adhesive force of the sealant on the glass, thus reducing the sealing effect of insulating glass.

Second: Desiccant

The role of desiccant is to adsorb moisture and volatile organic solvents. It also adsorbs water vapour in the air layer during the life of insulating glass.

To maintain the insulating glass with a qualified initial dew point, a qualified desiccant must be used to meet three critical functions simultaneously. If the desiccant’s adsorption capacity is poor, it cannot effectively adsorb the moisture that enters the air layer through diffusion. This can cause moisture to gather in the air layer, increasing moisture pressure and the dew point of the insulating glass. As a result, the possibility of fogging increases significantly. Additionally, the choice of desiccant should be made after considering its properties. The selection of desiccant is closely related to the type of insulating glass adhesive used and must be made in combination with it.


Sealing the edges of insulating glass properly ensures that windows and doors work efficiently. If the edges are not sealed correctly, it can affect the transparency and thermal insulation of the glass. If fogging occurs for an extended period, it can lead to mould or alkali accumulation on the inner surface of the glass. This can result in white spots and severely impact the insulating glass’s appearance and quality.

Therefore, choosing high-quality insulating glass sealant that meets national or industry standards is essential. When using double-layer insulating glass, the first and second sealants should be compatible and not be soluble or reactive. If they are, it can lead to glass surface contamination and ageing.

Third: Assembly of Insulating Glass

When assembling insulating glass, it is essential to be mindful of the different sealants used. Suppose the insulating glass sealant comes into contact with other sealing materials containing plasticising ingredients that can dissolve butyl sealant. In that case, these ingredients can migrate to the surface of the first sealant through the second seal of insulating glass. This can cause the first sealant to dissolve, resulting in thinning and flowing. To prevent this, conducting a phase solubility test is necessary to select compatible sealing materials for the insulating glass sealant. It is best to use sealing materials from the same manufacturer to reduce the likelihood of these issues.

To reduce and eliminate fogging in aluminium doors and windows with insulating glass, closely monitoring every step of the production process is necessary. This will help to eliminate any unqualified products.

What Causes Glasses Fogging Up?

  1. If the construction process during installation is not good enough, the sealant may crack after a certain period. This can cause water vapour to enter the space between the glass layers. As the temperature increases, the water vapour evaporates and forms tiny water droplets when it comes into contact with the glass surface. This leads to the glasses fogging up.
  2. It is essential to ensure that the sink is correctly installed during the installation process. If the water surface inside the sink is higher than the profile, it can cause water to flow into the double-glazed interlayer. When the sunlight shines on this, water vapour can form mist, leading to double-glazing glasses fogging up.
  3. If the spacer does not leave a gap between the edge of the glass and itself after being pasted during installation, it will absorb rainwater onto the double-glazed glass. This can cause glass fogging up, which is a phenomenon of condensation between the glass panes.
  4. If the difference between the indoor and outdoor temperature is too great and the indoor air humidity is high, double-glazing glasses fogging up can occur.

How to Fix When Glasses Fogging Up?

  1. If the sealant is not tightly sealed, it can be removed. Then the glass should be cleaned and dried before proceeding with the glass sealant painting process.
  2. If the sink is not properly installed, you should remove and reinstall the window.
  3. If the spacer is already in place, you can add glass gaskets to the window or remove and reinstall the original spacer. It’s important to note that the spacer should be positioned at a certain distance from the edge of the glass window, generally around 2mm. During the glass window installation, be careful not to let the spacer get wet as this may affect the quality of the installation.
  4. If there is a significant temperature difference between the indoor and outdoor temperatures due to fog, you can open the window for a short time to reduce the temperature difference. This will help the fog on the window dissipate.


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