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Sealant plays an important role in bonding two or three insulating glass seals. If the surface of the insulating glass is improperly treated or the glass is not cleaned before using the sealant to seal the insulating glass, the sealant cannot maintain long-term bonding with any substrate. The use of the correct cleaning agent and compliance with the prescribed surface treatment and clearing procedures are the prerequisites for achieving a good bonding effect for insulating glass.

When cleaning the substrate, use suitable materials. These include clean, fresh solvents specified by the manufacturer of the structural silicone sealant, clean, white, lint-free cloth or other approved wiping materials, and a clean narrow blade. When cleaning begins, the assembler first removes all loose dust, dirt, oil, or other contaminants from the place where the structural silicone sealant on the substrate needs to be bonded. Next, wipe the substrate of the glued area with a cloth. 

The technical requirements for wiping are as follows:

(1) Wet a clean white cloth with the specified solvent and wipe the surface of the substrate.

(2) Wipe the wet solvent off the surface with a second cloth before evaporating. If the solvent dries on the surface of the substrate before wiping off the surface solvent with a second cloth, the dirt will be left again as the solvent is dried.

(3) Do not leave the dirt wiped off by the solvent in other wiping areas, because any remaining residues will pollute or fade the board surface (such as metal or glass curtain walls).

(4) When cleaning the deep and narrow interface, wrap a clean cloth around the narrow greasy knife. This makes it easier to clean the interface surface vigorously.

(5) The size of each rubbing surface is based on the sealing work that can be completed within 1 hour. If the wiped surface is rained or contaminated again, it should be wiped again.

(6) When the rag gets dirty, it should be replaced. It is easy to observe how dirty the cloth is by using a white rag.

The principles that must be kept in mind when using any type of solvent:

(1) To prevent the solvent in the entire container from being soiled, dirty or used rags should not be immersed in the solvent container. Wiping with a contaminated solvent will cause the sealant to fail.
(2) Be sure to use a clean container to hold the solvent.
(3) Smoking, sparks, welding, and the use of open flames are not allowed in or near the place where the solvent is used.
(4) Observe the precautions on the solvent label.
(5) The material safety information sheet (MSDS) must be obtained from the employer or the supplier or manufacturer of the solvent used. Before using solvents, you must read the material safety test sheet and follow all safety guidelines.

Primer

According to the substrate and the silicone sealant used, decide whether to use a primer. Most primers are a mixture of organic chemicals, resins, and solvents. The correct use of primer helps sealant and those surfaces that may be difficult to bond to ensure long-term and strong bonding.

The primer must never be used on the glass surface. The primer should not be used where the surface treatment is intact. The primer must be used according to the sealant manufacturer's instructions.

When using the primer, use the following materials:

(1) Pressure-sensitive protective tape;
(2) Rag;
(3) Clean, fresh primer, recommended by the structural sealant manufacturer.

When using primer, the following principles must be observed:

(1) Cover the edges of the contacts to prevent the primer from falling onto adjacent surfaces.
(2) Apply a layer of primer on the surface of the joint with an ordinary hard brush, a clean, lint-free cloth, or other approved wiping materials.
(3) Use the sealant after the primer has dried. The drying time depends on the surrounding conditions. But most primers contain solvents that evaporate quickly, so the drying time is very short, about 30 minutes.
(4) The primer contains a solvent. Smoking, sparks, welding buttons, and other types of open flames are not allowed in the work area.
(5) The material safety information sheet (MSDS) must be obtained from the employer or primer manufacturer. For safety reasons, you must read the MSDS before using primer products.

Application of sealant in the later maintenance of insulating glass 1

Application of sealant in the later maintenance of insulating glass 1

Masking

Before using structural sealant, use pressure-sensitive tape to protect the outer surface of the joint. The tape is applied from top to bottom, and a cloth is used to cover any horizontal surfaces that may come into contact with excess sealant when applying the glue.

Application of silicone structural adhesive

Sealants should be constructed following the highest professional standards, especially in structural adhesive assembly systems, because these systems do not have internal drainage systems. Unlike other curtain wall systems, the external sealing of the curtain wall is the only way to prevent water infiltration. This is why it must be assembled carefully with the best technology and strictly abide by the relevant written instructions.

Follow the guidelines below:

(1) Request a material safety information sheet from the sealant manufacturer or supplier. For safety, read it carefully.
(2) When applying glue on-site, you must be aware of the high possibility of pollution. Even if two rags are used correctly, airborne pollution from other working surfaces or secondary water pollution will affect the work results. Structural silicone sealants have high requirements for gluing technology, so care should be taken when working.
(3) Be very careful when handling glass sheets for structural assembly. The edges must be protected to avoid breaking. The reflective film, low-emissivity film, and high-performance glass should be handled carefully to prevent edge breakage.
(4) In addition, the sealant manufacturer should consult the door and window or metal assembly system manufacturer about the frame installation procedure, glass assembly sequence, and technical requirements.
(5) Most structural assembly systems use black silicone sealant. Black silicone sealant will not produce the aesthetic problems that other colors may bring. For example, black silicone sealant is not easy to see the air bubbles or the start and endpoints of the tool.
(6) When using a caulking glue gun or bulk glue dispensing equipment, follow the sealant manufacturer's instructions. If you use a pneumatic caulking glue gun, the pressure cannot be greater than 45psi (3.1X105Pa).
(7) Apply the sealant to the processed joints, carefully apply the glue upwards from the bottom of the vertical seam, and push the glue toward the front of the gun nozzle to ensure that the entire cavity is filled with glue. No air inserts or bubbles are allowed on the edges.
(8) After the glue is applied, the glue joint should be compacted immediately before the surface of the sealant is solidified.
(9) The shaping work should be tidy, and the sealant should be pressed forcefully so that it does not touch the edge of the interface. Compaction eliminates internal air bubbles and ensures good contact between the sealant and the substrate. The sealant is easy to consolidate on the surface, so repeated trimming is not recommended. Do not use soap or detergent solutions.

Application of sealant in the later maintenance of insulating glass 2

Application of sealant in the later maintenance of insulating glass 2

Curing time

The curing time of the sealant depends on the seam depth and relative humidity of the silicone sealant. In the structural adhesive assembly system, temporary fixtures must be used to fix the glass until the sealant is cured. When the room temperature is above 50°F (10°C), it usually takes 14 to 21 days.

Cleaning and maintenance

The glass surface must be cleaned following the glass manufacturer’s recommendations.
All structural glue joints must be inspected annually by the architect and/or owner’s agency. Pay special attention to the installation of drainage pipes related to the structural adhesive assembly of insulating glass during the inspection.

Any glass or insulating glass with obvious condensation in the air compartment must be replaced as soon as possible. Otherwise, it will eventually affect the structural integrity of the door and window system and may cause danger to the occupants and pedestrians in the building.

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