Like the time I mixed a three part sealer together and the hardener sunk to the bottom of the sprayer,
and I sprayed it unknowingly...
leaving a huge greasy dark stain on the stamped concrete pool deck stairs going up to the spa!!!
That one was not easy to fix.
Or how about the time I applied a stain across the floor of an entire two bedroom home, and after...
it didn't look like it was stained at all... curious, I called the rep and he said "the stain colors will pop after you seal it".
So I applied the first coat of sealer and...
it looked like raw concrete, without and colored stain at all... Ouch!
And that one was even harder to completely redo!