The Instructment on the Compatibility Test of Silicone Structural Sealant
Structural Glazing Sealant Application
1. Apply the sealant by pushing the bead ahead of the nozzle and making sure that the entire cavity is filled. Tooling should be done neatly, forcing the sealant into contact with the sides of the joint, thus helping to eliminate any internal voids and assuring good substrate contact. Air pockets or voids within the structural cavity are not acceptable.
2. Due to the smooth consistency of SS621 Silicone Structural Glazing Sealant, tooling agents such as water, soap or detergent solutions are not necessary or recommended. Dry tooling is recommended.
3. Sealant application is not recommended when the temperature is below 40°F (4°C) or if frost or moisture is present on the surfaces to be sealed.
4. SS621 Silicone Structural Glazing Sealant works best when applied to surfaces below 104°F (40°C).
5. SS621 Silicone Structural Glazing Sealant should not be applied in totally confined spaces since the sealant requires atmospheric moisture from the air and release of cure by-products to cure properly and develop typical properties. In a typical SSG cavity, cure depths up to 3/4” from an air interface will generally cure satisfactorily and reach maximum properties within several days. Cure depths > 3/4” may take significantly longer time to cure and when applied in a single application may not cure satisfactorily. Please consult Guangzhou Baiyun Chemical Industry Co., Ltd. technical services for additional information on depth of cure for this product.
The cure rate of this product depends upon temperature and the availability of atmospheric moisture. Under Standard Conditions (relative humidity of 50 ±5% at an air temperature of 73.4 ±2°F [23 of ±1°C]) this material can attain a cured thickness of 2-3 mm per 24 hours (assuming ample access to atmospheric moisture). As temperature decreases, the cure rate slows down (and vice versa). Low moisture environments will also reduce the cure rate. Near-confined spaces which limit the overall access to atmospheric moisture will cure only from that surface which has access to the atmosphere. Colder temperatures can significantly increase cure times and can open the possibility of sealant irregularities if joint movement occurs while sealant is not fully cured. The following reference provides additional information on Movement-During-Cure of sealant joints: ASTM C1193 – Standard Guide for Use of Joint Sealants; section 12.5.
Disclaimer
Guangzhou Baiyun Chemical Industry Co., Ltd. will not:
1. Design sealant joints.
2. Provide comments on the structural integrity of overall framing system(s).
3. Provide long-term performance data.
The design professional has final responsibility for the determination of structural sealant joint dimensions based on project conditions, design wind load(s), glass or panel sizes, anticipated thermal, seismic or other movement of the system.
The ASTM C1401 Standard Guide for Structural Sealant Glazing provides a thorough overview of design topics and information for use in SSG systems.
Installation
Surface Preparation
Sealants may not adhere or maintain long-term adhesion to substrates if the surface is not prepared and cleaned properly before sealant application. Using proper materials and following prescribed surface preparation and cleaning procedures is vital for sealant adhesion. Guangzhou Baiyun Chemical Industry CO., LTD. can provide quality control information and suggestions to user upon request.
Materials
1. Use clean, fresh solvent as recommended by the sealant manufacturer’s test report. When handling solvents, refer to manufacturer’s MSDS for information on handling as well as safety and personal protective equipment. Isopropyl Alcohol (IPA) is commonly used and has been proven useful for most substrates encountered in SSG systems. Xylene and Toluene have also been found useful on many substrates.
2. Use clean, white cloths free of lint or other lint-free wiping materials.
3. Use a clean, narrow-blade putty knife when tooling structural silicone into the cavity.
4. Use primer when required.
Cleaning Procedures
1. Remove all loose material (such as dirt and dust), plus any oil, frost or other contaminants from the substrates to where the structural silicone will be adhered.
2. Do not use detergent to clean the substrate as residue may be left on the surface.
3. Clean the substrates receiving the sealant as follows: Using a two-rag wipe technique. Wet one rag with solvent and wipe the surface with it, then use the second rag to wipe the wet solvent from the surface BEFORE it evaporates. Allowing solvent to dry on the surface without wiping with a second cloth can negate the entire cleaning procedure because the contaminants may be re-deposited as the solvent dries.
4. Change the cleaning rags frequently, as they become soiled. It is easier to see the soiling if white rags are used. Do not dip used wipe cloths into solvent as this can contaminate the solvent. Cleaning with contaminated solvent can result in sealant adhesion issues. Always use clean containers for solvent use and for solvent storage.
5. When cleaning deep, narrow joints, wrap the cleaning cloth around a clean, narrow-blade putty knife. This permits force to be applied to the cleaned surface.
6. Clean only as much area as can be sealed in one hour. If cleaned areas are again exposed to rain or contaminants, the surface must be cleaned again.
Primers
SS621 Silicone Structural Glazing Sealant will bond to many clean surfaces without the aid of a primer. For difficult-to-bond substrates, the use of a primer or special surface preparation should be evaluated. An evaluation should be made for each specific application/substrate to determine quality of bond. When properly used, primers help assure strong and consistent sealant adhesion to surfaces that may be difficult to bond. Most primers are a blend of organic and inorganic chemicals, resins and solvents. NEVER APPLY PRIMER TO GLASS SURFACES. Obtaining the proper materials, as well as following the prescribed procedures, is vital to ensure the successful use of primers. PRIMER APPLICATION IS NOT A SUBSTITUTE FOR SURFACE PREPARATION. Consult Guangzhou Baiyun Chemical Industry CO., LTD. primer datasheet(s) for specifics and recommendations for use.
Caution
Primers may contain solvents. When handling solvents, refer to manufacturer’s MSDS for information on handling as well as safety and personal protective equipment.
Masking
1. To simplify clean up of excess sealant, use easy to release, pressure sensitive tape to mask adjacent surfaces before applying the structural silicone sealant.
2. Start from the top down and overlap the runs. Tool in direction of over-lap so that masking is not disturbed during tooling.
3. Remove masking immediately after application of silicone or as soon as possible or practical.
4. Drop cloths can be used to cover any surfaces likely to collect excess sealant removed during tooling operations.
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