Denatured and ineffective.
Because it became difficult with trading.
Sex, when you got hor*y
It can become moist and stick together, but salt does not get stale. If it is moist, break it apart and place in the oven for a few minutes on about 170 degrees on a cookie sheet.
Ineffective
No. Not if they are made to be disposable. Use only once and then throw away, they are not effective after they get moist from respirations, so they are good for only short term use and only for one time.See the related question below for more information about using face masks for protection from the flu.
sugar hardens in cold weather
They simply dry out & become ineffective. most are good for 6 mos.
Some bacteria get used to the drugs, and they no longer kill bacteria.
Poison gas had been used extensively by both sides in the First World War. Even though it had been relatively ineffective, often causing as much trouble for the side using it as for the enemy, there was no way to be sure it would not be used again. Thus gas masks were issued as a precaution. Michael Montagne
"We all wear masks, and the time comes when we cannot remove them without removing some of our own skin." - André Berthiaume "Life is to be lived, not controlled, and humanity is won by continuing to play in face of certain defeat." - Ralph Ellison "We understand how dangerous a mask can be. We all become what we pretend to be." - Patrick Rothfuss
An example of an ineffective affirmation