I think you are talking about cleats. If that is the case then yes, they are safer than metal but wear out sooner. Also the shoe must be the interchangeable kind.
If they appear to be in good condition, then NO, do not replace them.
The density of rubbers stoppers can be very different from one to the next. This is because there are different stoppers at different densities.
NO!
Normally cork or rubber is used as a stopper in a flask.
A cork borer is a tool used for boring holes in cork or rubber stoppers. It is commonly used in laboratories to obtain uniform samples or to create holes for inserting glass tubing or thermometers into stoppers.
use to cover the test tube, basically like a cork.
Heating at high temperature can be dangerous.
Rubber stoppers are widely used for the commercial, industrial and scientific markets. They are made from different types of rubber and available in various sizes and styles depending on applications.What are Rubber Stoppers used for?Possible uses of rubber stoppers are wide and varied such as :Mechanical StopBumpersVibration MountGrippersClampsSticky feet for platformFits into Test Tubes, Boiling FlaskPipe stoppersPaint masksTube plugsDoor stopperThe kind of rubber stopper used in chemical laboratories is a plug which fits into the top of a test tube or flask, often with a hole or holes bored in it for the insertion of a piece of glass tubing. They used to be made of cork but rubber is less likely to disintegrate and get into the contents of the flask or tube.
Butyl rubber stoppers offer advantages in pharmaceutical packaging due to their chemical resistance, impermeability to gases, and ability to maintain a tight seal, preventing contamination and ensuring product integrity.
Cotton balls are absorbent and can be used as a makeshift filter in certain experiments when a rubber stopper is not available. However, rubber stoppers are a better choice for sealing glassware due to their durability and ability to create a tight seal, preventing leaks or contamination in the experiment.
A stopper can be made of various materials such as rubber, cork, or glass, depending on the application. Rubber stoppers are commonly used in laboratories for sealing test tubes or flasks, while cork stoppers are often used for sealing bottles of wine or spirits. Glass stoppers are also used for sealing high-end bottles and can provide an airtight seal.
Commonly, rubber stoppers are used in scientific experiments to plug and test tubes. Their purpose is to prevent liquids, and sometimes gases, from escaping their containers.