- What is Silicone Sealant?
Silicone sealant is a commonly used adhesive in households. Its primary components include silicic acid (Na2O·mSiO2), acetic acid, and organic silicone. Sodium silicate, which is easily soluble in water and has a certain viscosity, is also known as glass glue, water glass, or saponin. Silicone sealants are generally non-toxic but can be corrosive, both in acidic and neutral forms. Acidic silicone sealant is primarily used for general bonding between glass and other building materials. Neutral silicone sealant, on the other hand, overcomes the corrosion issues of acidic sealant on metal materials and reacts less with alkaline materials, making it more versatile and slightly more expensive than acidic sealant. Neutral silicone sealant is further categorized into stone sealant, mildew-resistant sealant, fire-resistant sealant, pipe sealant, etc.
- Types of Silicone Sealant
- Single and Double Component: Silicone sealants can be categorized into one-component and two-component types based on packaging. One-component silicone sealant cures by reacting with air, changing its physical properties. Two-component silicone sealant is divided into A and B groups, which cannot solidify independently but will solidify when mixed. The market predominantly offers one-component silicone sealant.
- Acid and Neutral Classification: Silicone sealant is divided into acidic and neutral types. Acidic silicone sealant is primarily used for bonding glass and other building materials. Neutral silicone sealant has a broader application range due to its non-corrosive nature towards metals and its lower reactivity with alkaline materials. Its market price is slightly higher than acidic sealant. A special type of neutral silicone sealant is silicone structural sealant, which is used directly for metal and glass structures or non-structural bonding assemblies in glass curtain walls. It has the highest quality requirements and product grade among silicone sealants and the highest market price.
- Color Classification: Silicone sealant is available in various colors, including black, porcelain white, transparent, silver gray, gray, and bronze. Other colors can be customized according to customer requirements.
- Weatherproofing and Mildew Resistance Classification: Weather-resistant silicone sealant is suitable for sealing various curtain walls, especially glass curtain walls, aluminum-plastic panel curtain walls, and stone dry-hanging systems. It is also suitable for sealing joints between metal, glass, aluminum, ceramic tiles, plexiglass, and coated glass. Anti-mildew silicone sealant is a growing trend, offering longer and stronger adhesion than ordinary sealant, making it ideal for wet and mold-prone environments such as bathrooms and kitchens.
- Features and Performance of Silicone Sealant
- Quality Indicators: The quality of silicone sealant can be evaluated based on its viscosity, tensile strength, mildew resistance, ease of cleaning, and color stability. Silicone sealant is available in various colors, including white, black, colored options, and transparent.
- Types Based on Performance: Silicone sealant is divided into neutral silicone adhesive and acidic silicone caulk based on its performance. Acidic silicone sealant has a wide bonding range and excellent adhesion to most building materials like glass, aluminum, and non-oiled wood. However, it cannot be used to bond ceramics and marble. Neutral silicone sealant can be used to bond ceramic sanitary ware, marble, and other materials.
- Varieties of Sealant: The market offers various types of silicone sealant, including acidic sealant, neutral weatherproofing sealant, structural silicone sealant, stone silicone sealant, neutral mildew-resistant silicone, hollow glass sealant, aluminum silicone sealant, aquarium sealant, silicone adhesive for large glass bathroom sealant, and acidic structural silicone sealant. Each type serves specific applications and requirements.
- How to Apply Silicone Sealant
(1) Usage
One-component silicone glue is ready for immediate use. Simply squeeze it out of the cartridge with a glue gun and trim the surface with a spatula or wood chips for a neat finish.
(2) Sticking Time
Silicone glue cures from the surface inward, with drying and curing times differing. Repairs to the surface must be done before the silicone sealant dries. For acid sealant and neutral transparent silicone adhesive, this is generally within 5-10 minutes; for neutral colored silicone caulk, it’s typically within 30 minutes. If using color separation paper, remove it before the sealant skins over.
(3) Curing Time
The curing time of adhesives and sealants increases with bonding thickness. For example, 12mm-thick silicone caulk may take 3-4 days to fully cure, but the outer 3mm layer will cure within about 24 hours. When bonding glass, metal, or most woods, it achieves a peel strength of 20 lbs/in after 72 hours at room temperature. In partially or completely closed environments, curing time depends on the seal’s tightness; in an absolutely closed space, it may never fully cure. Raising the temperature can soften the glue. The gap between metal bonding surfaces should not exceed 25mm. Always check the bonding effect before using the bonded equipment, and note that acid silicone caulk may release a smell due to acetic acid volatilization during curing.
(4) Bonding
A. Clean metal and plastic surfaces thoroughly to remove oil. Rinse plastic with acetone, sand the rubber surface with sandpaper, then rub with acetone, following safety precautions.
B. Apply silicone sealant evenly to the prepared surface. When bonding two surfaces, place one side first and apply sufficient force to squeeze the other side, expelling air but avoiding squeezing out the glue.
C. Allow the bonded device to cure at room temperature until the glue sets.
(5) Sealing
Follow the same steps as in Point (4) when using silicone glass glue for sealing. Force the sealant into the joint or gap to ensure full contact with the surface.
(6) Cleaning
Uncured silicone caulk can be wiped off with a cloth or paper towel. Once cured, it must be scraped off with a scraper or solvent like xylene or acetone.
(7) Construction Skills
For 2mm silicone caulk, ensure the silicone sealant nozzle is cut properly, at an angle, with a caliber just large enough for the gap. After applying the glue, smooth the uneven surface with a plastic-covered finger in one continuous motion, avoiding repeated smoothing.
- How to Remove Silicone Sealant
Scrape off silicone sealant on glass and stone with a blade. On wooden veneer, use a nail to scrape off the caulk, then carefully scrape the remaining large pieces with a blade.
- How to Store Silicone Sealant
Store silicone glue in a cool, dry place below 30°C. High-quality acid silicone glue can be stored effectively for over 12 months, while regular acid silicone glue has a shelf life of 12 months. Neutral weatherproof and structural glue guarantee a shelf life of 9 months. Once the cartridge or sausage is opened, use it promptly. If not fully used, seal the bottle tightly. When reusing, unscrew the bottle mouth to remove any blockages or replace it.
- Precautions When Using Silicone Sealant
(1) Silicone glue can darken and develop mold, even waterproof varieties. Therefore, avoid using it in areas with prolonged water exposure.
(2) Silicone sealant is soluble in organic solvents like oil, xylene, and acetone. Do not apply it to substrates containing these substances.
(3) One-component silicone sealant requires air moisture to cure, except for special types like anaerobic glue. It is unsuitable for confined, dry spaces.
(4) The bonding substrate must be clean and free of attachments like dust to ensure strong adhesion and prevent sealant failure.
(5) Acidic silicone caulk releases irritant gases during curing, which can irritate eyes and respiratory tracts. Open windows after application and wait until gases dissipate.
