I have the same gallon. I won't even take the top off unless I'm in a large warehouse or outside. Get caught down wind and you won't be able to keep your eyes open and you'll cough like you're dying. But let me tell you, it did the same work as a wire wheel on a prop blade but in 30sec instead of 3min

Muratic Acid Effects
 

Some before and after shots. Under where the gunk was, the boat isn't as badly oxidized. Weird :angry-smiley-038: