Loctite is a powerful threadlocker that keeps fasteners tight, but the different color varieties can be confusing. What's different between red and blue?

Loctite threadlocker comes in a variety of formulations, each suited for various tasks. Sometimes the difference can be very subtle, like Loctite 242 and 243.

Like, where do you use “Red” Loctite, and how do you take it apart after you realize Red was the wrong type of Loctite to use in that particular spot?

According to Loctite’s manufacturer, Henkel, Loctite (loctiteproducts.com) does go bad.The technical data sheets of both thread-locker 271 (red) and 242 (blue) say that the shelf life of each is ...