There are hundreds of sealants from which you can choose; how do you know which one is right for your project? The first step in deciding which silicone sealant is the best begins with determining which materials you’re using and where they’ll be located. After choosing your silicone and materials, application is fairly universal. But what about curing? The main difference between silicones begins to show itself during this step.

Acetoxy cure silicones derive their name from their release of acetic acid, which gives off a strong vinegar like smell while curing. These silicones cure with the presence of atmospheric moisture and generally have a very fast cure time (24 hours) (10 min. skin and 17 min. tack) and adhere better to many surfaces. Because of the acid released, however, acetoxy cure silicones have a stronger smell than neutral cure silicones, and the acid can have adverse effects on some delicate electronic components. The acid could even be corrosive to certain substrates and metals. With use on medical devices, they can cause bleeding.

Uses include:

• windows and door frames
• kitchens-backsplashes
• countertop sealing
• bathrooms & bathtubs

However, acetoxy cure silicones such as our Chem-Set RTV4500 provide their fair share of usefulness; some of these silicones are even biocompatible. This means that they work in harmony with the body’s natural processes, making them useful for medical device manufacturing, although they are not medical grade ISO 1000. When cured, they are food safe with USDA approval and VOC compliance. They also meet Green Building Standards and are military grade.

Neutral cure silicones, like our RTV7500 , ShinEtsu KE-45, are unique in that some release a substance known as methyl ethyl ketoxime while curing, and others release acetone. These substances are non-corrosive, thixotropic and make neutral cure silicones ideal for electronics applications. These silicones also release a much subtler odor, making them great candidates for indoor applications such as kitchen installations, even though the cure time is longer than that of acetoxy cure silicones.

Uses include:

• roofing
• industrial gaskets
• HVAC
• compressor pumps
• refrigeration

Neutral cure silicones are ideal for delicate surfaces or otherwise challenging applications; in fact, NASA has received low-outgassing approved silicones to be used in the aerospace, electronics, and optical fields due to the low odor and gentle, non-corrosive application. Tests are beginning on neutral cure silicones for biocompatibility as well.

For the heavy-duty sealant jobs, hybrid adhesives such as our Chem-Set MS-35 polyether adhesive combine the sealing capabilities of a silicone with the strength of a construction adhesive. These adhesives are vibration dampening, ready-to-use without priming, and possess the fast cure time you’ve come to expect of a silicone sealant.

To view our complete line of silicone sealants, click here. Need help deciding which sealant is right for your project? Our representatives are here to help! Give us a call, toll-free, at 1-800-220-1966 or send us an email at sales@chemical-concepts.com. We look forward to hearing from you!