After choosing the correct gasket to go between the two flanges, along with a matching gasket sealant, it is time to put it all together. Modern gasket sealants are very versatile and can be bonded to a number of surfaces including glass, metal, ceramics and some types of plastics. However, precautions and preparations must be made before applying, as well as using the sealant correctly. Here’s how you should go about applying the sealant successfully.
All surfaces should be cleaned thoroughly with a suitable solvent to remove any oil, grease and dirt. The best solvents for this purpose are Naphtha or Methyl Ethyl Ketone (MEK), although it should be emphasised that care should be taken when applying these and any other solvent. Ensure that all surfaces are wiped dry before applying sealant.
Most sealants will bond to various types of clean surface without a primer. However, some substrates are difficult to bond, so a primer will need to be applied beforehand. Check with your sealant’s manufacturer or the accompanying instructions for information on an appropriate primer.
Unless a primer is required, you should apply the sealant to the prepared surface. Apply an even coat to all sides of the gasket. Where there are broad surfaces, apply in a thin ribbon of 6mm or less in diameter around the surface edges. Allow the sealant to air-dry until it becomes tacky when touched.
Most sealants form a surface skin at a temperature of 25 degrees centigrade and a humidity of 50%. High temperatures and humidity accelerate the curing process, whereas low temperatures and low humidity slows it down. It is not advisable to manipulate the sealant any further once the skin has formed. The sealant will be ‘tack-free’ 15-30 minutes after application.