By: Mike Dixon, firstname.lastname@example.org
Due to some discussions on the lubrication of keg parts when reassembling, and a little confusion, I thought it would be nice to go over what exactly “keg lube” may be. In all cases it should be tasteless, odorless, and FDA approved for food contact. Keg lube prolongs the life of the O-rings, and can assist in sealing the keg. Generic keg lube is usually one of two things, silicone compound (grease/lubricant), or petrol gel.
The differences between silicone compound and petrol gel are the price, and some of the properties. The price of petrol gel is about 6 times less than the price of silicone compound. Petrol gel also can inhibit head retention.
In theory the beer only comes in contact with the poppets. Petrol gel can be used everywhere but on the poppets if the brewer is worried about an effect on head retention, and silicone compound can be used on the poppets. If the brewer shakes the keg for carbonation, then he or she should take care to utilize silicone compound everywhere to insure no loss in head retention due to beer contact with all lubricated surfaces.
Even a small tin of keg lube will last a very long time. Most of the lubricants come in small one ounce or less tins, 4 oz or greater tubes, or silicone in spray cans. They may have many names Petrol Gel, Lubri-Film, Silicone Compound, Silicone Lube to name a few. If purchasing outside of a homebrew shop, be sure they are FDA approved, and no problems should arise. Scuba shops also sell a food grade silicone lube.
Some suggested replacements have been Vaseline, and KY Jelly. Vaseline can be used, but it does not have the properties of being tasteless and odorless. KY Jelly is water soluble, and could become dissolved in the beer. It also dries over time, and would not be a good choice. In general if I did not have either silicone, or petrol gel, and had to reassemble the keg, I would use nothing at all.
The wholesale cost of silicone spray in a 13 oz can is $5.64, silicone compound in a 5.3 oz tube is $12.00, petrol gel in a 4 oz tube is $1.54, and lubri-film in a 4 oz tube is $3.30. Since it lasts virtually forever, my choice is silicone compound from my local brew shop.