A trace of olive oil is used as a release agent to make screw cap lids easy to remove from home hot preserved food.
Introduction
Previously I have posted on tricks to release stubborn screw caps that happen with premium hot preserving in reused twist cap jars as home.
Back in my laboratory days in the dairy industry, I worked with rubber quite a lot. I learned quickly that a tiny trace of lubricant or release agent could greatly reduce the friction between glass or stainless steel and rubber. “It could make a hard or impossible job easy. The agent could be soapy water, milk or Shhh……spit when desperate”.
I also noticed that our vast supply of new twist cap lids did not initially have this tight gripping problem. I suspected that they were treated with a trace of release agent, at the factory, that stopped them ‘sticking’. I presumed that this agent washed off the recycled lids when they were reused.
I don’t have a photo of the mystery trace of release agent, so I offer an ode to lighten up a bit;
A search for a release agent for food fit,
Smeared invisibly on butyl rubber to sit,
A manufactured chemical or something natural?
Twill be born again extra virgin olive oil, not spit.
Jar sealing with a release agent
This is all speculation, but it was time to try adding my own release agent to the synthetic rubber seal of my second-hand lids. It would be in the form of a trace of olive oil.
I assume the seal is made of butyl rubber. It is used a lot in laboratories. “It is a soft and smooth synthetic rubber that is impermeable to gases. It has a softness that is great for sealing, but is as ‘tough as old boots’ and undamaged by oils. The seal is luckily in a wonderfully protected location within the lid. The lip of the jars are beautifully smooth and rounded to make a good seal with the rubber.
I put a trace of olive oil on my finger and smeared that around integral rubber seal within the lid. I filled the jar with boiling water and sealed the jar according to the hot sealing method in another post.
When the jar was cool the next morning the lid came off with the force that I would expect to use on a ‘shop-bought’ jar of jam.
If this method continues to work with long term storage, as I expect it will, it will be a winner for home preserving.
“It should help to avoid getting those mongrel jars of preserves that no one uses because no one in the house has the strength to open it.”
Tim
