What’s the biggest mistake you’ve made during your time as a scientist and how did you fix it?

Question: What's the biggest mistake you've made during your time as a scientist and how did you fix it?
- Keywords:
  fix,
  mistake
Asked by Teagx to Abid, Donna, Sanjib, Thomas, Avril on 15 Jun 2017. This question was also asked by Spoon.
- Donna Johnson answered on 15 Jun 2017:
  
  I broke a part of a piece of equipment. It was a special glass cylinder (an expensive one!) that made a vacuum in the machine. I couldn’t fix it so i had to go and tell my boss and then he had to buy another one. It was very embarrassing and i was a a lot more careful after!
- Avril Tucker answered on 18 Jun 2017:
  
  I dropped a jar of eosin powder. It has a tiny particle size. It didn’t look that bad until I started to clear it up. Before I knew it the whole dispensary was red!!!! It just smeared everywhere!!!

Question: What's the biggest mistake you've made during your time as a scientist and how did you fix it?