 For example, electrical feedthroughs containing ceramic insulators will fail if the titanium forms a conducting film which bridges the ceramic insulator.Samples may become contaminated by titanium if they have line-of-sight to the pump.Also, titanium is a very hard material, so titanium film which builds up on the inside of the chamber may form flakes which fall into mechanical components (typically turbomolecular pumps and valves) and damage them.