[rey]

By the way, I ask this as an employer has asked me to mix two or three different bathroom cleaner, a 409 and scrubbing bubbles and comet.

[rickmichaels]

Might not be a good idea.

[Black Agnes]

The first is the product of a reaction. The second ones are reactants.

I’d probably not mix the reactants outside a lab.

But that’s just me.

Unless you’re having a ‘hold muh beer’n watch this!’ moment and fancy EMT’s and possibly serious injury or death in your future.

http://chemistry.about.com/od/toxicchemicals/a/Mixing-Bleach-And-Ammonia.htm

Having said that, I accidentally picked up the wrong spray bottle while cleaning the bathroom once. I got out of there quick, turned on the fan and didn’t do that again!

[USNBandit]

Had a guy in my dorm end up in the emergency room from mixing comet and ammonia. I think off gassed chlorine, but I can't remember.

The comedian Gallagher had a bit about a mildew cleaner having a warning to use in well ventilated areas. If it was well ventilated, he reasoned, he wouldn't have a mildew problem.