Next, apply a small amount of grease to the seal lip(s) and the area of the shaft in contact with the seal.  When using a double-lip seal, fill the small cavity between the two lips with grease as well. This both protects the lips during initial installation and break-in, and also acts as another barrier keeping contaminants out. When installing rubber-coated seals, apply lubricant to the outside diameter as well. This will help prevent the seal from rebounding or backing out from its mounting place.

Leather is probably the oldest of the lip materials still in common use, but the move towards mass production methods has seen a massive increase in the development of synthetic rubbers which lend themselves to accurate and repeatable injection and compression moulding. Nitrile (NBR) is still by far the most common elastomer for “normal” use, whilst Viton® (FKM/FPM) is rapidly replacing Polyacrylate (ACM) and Silicone (VMQ) for high-temperature applications. Viton® also has high resistance to abrasion and chemical attack making it a preferred elastomer. Recent developments in the use of PTFE for Rotary shaft seals has caused widespread interest particularly for high-speed shaft rotation or poor lubrication applications.