What to Look for in a Gasket Sealant
If the mating surfaces are less than perfect when connected, you can use a gasket to bridge the gaps between them. As for the gasket sealant or sealing cement, it's an adhesive compound or sealing element you use to further seal the gasket to ensure of zero leakage when it's fitting two mating surfaces together as tightly as possible.
Gasket Sealant Shopping Recommendations
- Shellac: Also known as Indian Head, shellac is a sealant that's idea l for use with paper or cardboard gasket that are mounted in low pressure and/or low temperature conditions. It's not a sealant that's idea for environments that can reach 300 to 350 degrees Fahrenheit in temperature. This sealant type is engine-fluid resistant, which means it is best used for gasket mounting differential cover gaskets, time cover gaskets, and thermostat gaskets.
- High Tack: This gasket sealant is available in tubes or a brush-top bottle. It can be used in the same applications as shellac. However, it's better than shellac because it can sustain temperature of up to 500 degrees Fahrenheit. It remains tacky all throughout and can also resist diesel, propane, and kerosene fuel corrosion.
- Form-a-Gasket Sealers: There are several types of this sealer, which includes brushable, slow drying, and non-hardening (has the ability to seal solid gaskets, machined surfaces, or metal flanges in thick or thin coats); slow drying and non-hardening (it works best on paper oil pan or cork gaskets); and fast drying and fast-hardening (permanent sealing applications such as metal-to-metal gasket connections, threaded connections, and block expansion plug installations). All three types can withstand 400 degree Fahrenheit conditions.
- Copper Gasket Sealant: This sealant is available in aerosol or brushable forms. This is a fact-acting, fast-drying sealant with metallic content suspended within it to ensure tougher seals and better heat dissipation (it's rated for 500 degrees) from the sealed gasket. It even promotes better heat transfer between the mating surfaces connected by the gasket (usually exhaust manifold or cylinder head gaskets).
- Anaerobic Sealers: This sealant type is made for applications wherein outside air isn't available to assist the drying process of the sealing chemical. They were made to meet Original Equipment Manufacturer requirements for metal-to-metal applications of a noncorrosive gasket maker. It's best used for filling small imperfections or situations where a replacement gasket isn't available any longer.
- RTV Silicone Sealers: RTV silicone sealers are available in caulk-gun cartridges, aerosol cans, and spreadable gel tubes. It's a room-temperature volatile silicone sealant that can seal up gaskets or act as the gasket itself if there are no replacement gaskets available. 500-degree applications require grey, black, and blue sealers. Orange and red are for 650-degree jobs and copper is best for 750-degree work.
- Hylomar:This relatively new aftermarket sealant variant has been around for 30 years. This polyester urethane type of compound can withstand 500-degree temperatures without hardening. It's a consistently tacky, non-setting sealant that allows for repeated disassembly or reassembly of gaskets as required by mechanics. It's mostly used by racers.
To Sum It All Up
A gasket is a mechanical seal that fills the space between mating surfaces, which you'll commonly see in cars. Meanwhile, a sealant assists the gasket in its job. When buying a sealant, match the specific gasket type or application with the sealant categories outlined above. This will make it easier for you to zero-in on the right one every time.