DOWSIL™ 1200 OS Primer

Primer for silicone adhesives and sealants

An air-drying primer supplied as a dilute solution of moisture-reactive materials in volatile siloxane and is used to improve both the quality and rate of room temperature adhesion of vulcanizing silicone sealants to a variety of commonly used non-porous substrates.

Application Applications

• Battery pack, plates and assemblies, components, connectors, engine systems, housings
• DOWSIL™ 1200 OS Primer improves the bond/adhesion of RTV and thermosetting silicones to many materials:
• Metals
• Ceramics
• Glass
• Wood
• Masonry
• Engineering plastics

Features and Benefits

• Improves the adhesion of silicone sealants to many substrates
• Useful for both moisture-curing RTV silicones and thermosetting silicones
• Provides more uniform and stronger bonds
• Complies with South Coast and Bay Area Air Quality Management Regulations for architectural waterproofing subfloors
• Low VOC (Volatile Organic Compounds) level of 76 g/l Meets many international regulations including the European Union
• Formulated for low toxicity
• The OS solvent used does not deplete the ozone layer. Labeling = ozone safe
• The primer is suitable for weather sealing and structural glazing applications
• Suitable for most metals, glass, ceramics, masonry, wood, fabrics and some plastics (including FR-4)

properties

Usage

For many surfaces, much stronger and more uniform bonds are achieved by pre-priming them prior to applying the silicone sealant. For best results, follow the steps below on all surfaces except silicone rubber.

1. If necessary, thoroughly clean and degrease the surface with 2 cloths and a suitable solvent. Leave the surface to dry.
2. Apply a thin layer of DOWSIL 1200 OS Primer with a clean white cloth or brush. In most cases, a thin layer of primer will provide the best adhesion. If you notice a white chalky residue after a few minutes of drying, wipe it off with a clean cloth.
3. Under normal temperature and humidity conditions (room temperature, 50% RH), allow the primer to air dry for 15 to 90 minutes. Because the primer cures on contact with moisture from the air, low humidity requires a longer drying time. The optimal drying time for a particular area should be determined prior to use. A primer that has been left to hard cure will no longer increase adhesion. Drying longer than 6 hours at normal temperature and humidity should generally be avoided.
   
4. Apply silicone sealant.
5. Note: Always use a separate container when applying with a brush. To avoid contamination and product deactivation, do not mix used materials into a fresh or unused primer can.