Question

Questions about "safety" in labs

What does it mean by
"Replace all container lids (finger tight) immediately after use"

and

"Replace all container lids (finger tight) immediately after use"

Answer 1

Contamination?

Answer 2

It is saying that you should take samples/reagents from the bottles and then as soon as you have them out, put the lids back on and tighten with your fingers (in more advanced labs with more potent chemicals, etc... you might need to secure the bottles in other ways).