If a flare splits when being made, it may be due to the age of the tubing. Old tubing becomes brittle after a certain period of use and cannot be flared satisfactorily.

A remedy is to anneal the tubing by heating to a dull cherry red or blue color and allowing it to cool in air or water.

Pounding, rough handling, or bending the tubing tends to harden it. Hard drawn tubing cannot be bent or flared unless annealed.