Just as I now always look at my friends' garage doors to see
what they need help fixing, now I'm constantly looking for
brown stains in my friends' toilets.

Here's one I found at one friend's house:
http://www1.picturepush.com/photo/a/...g/12800209.jpg

And, here's another, at a different house:
http://www3.picturepush.com/photo/a/...g/12800236.jpg

There were many new lessons learned though, mostly from
being way too casual around the acid and therefore making
a few mistakes by not being cautious enough.

For example, my hands are killing me, because I cupped the
acid back and forth to cover the stains in an attempt to
speed up the process:
http://www1.picturepush.com/photo/a/...g/12800254.jpg

Another lesson learned is to remove the baggie over the filler
tube when you start refilling the toilet! I left the baggie on
to get the phone, and when I came back, acid was all over the
stone floor (making it slippery to the touch!).
http://www4.picturepush.com/photo/a/...g/12800282.jpg

Another lesson learned is that you can peel back the plastic
wrap over the bowl to scrub the stains to move the process
along quicker - but - you'll get one hell of a few good
coughing fits out of being that close to the open bowl of
acid. My chest is still hurting - like when you have bronchitis:
http://www4.picturepush.com/photo/a/...g/12800322.jpg

Yet another lesson learned is that some people are really
picky when it comes to chemicals. This shot is at a friend's
house, where I didn't bother with the funnel and just poured
the acid directly down the tube. Of course, a lot went into the
bowl - which smoked and fumed. Hours later, my friend swore she
could still smell the acid (although I don't believe her):
http://www4.picturepush.com/photo/a/...g/12800357.jpg

Another lesson learned was that the plastic wrap actually
works BETTER than does the rubber banded sandwich bag, especially
when you remove it to pour more acid. The plastic wrap throws
away more easily without keeping acid in all the folds:
http://www3.picturepush.com/photo/a/...g/12800391.jpg

Another good lesson was to not get cavalier about the acid.
Here you see me pouring it directly on the scrub brush in
the bowl. Problem was that droplets of acid started burning
my bare skin within minutes - even though they didn't hurt
at first.
http://www5.picturepush.com/photo/a/...g/12800463.jpg

In summary, the biggest thing I learned is that the damage
from the acid doesn't hurt too badly at first - but it lingers on.

Also, I learned you can clean the bowl directly, but, you'll
get a few whiffs in your lung - which you'll know when you
get 'em as you'll start coughing away immediately.

The splashes on the bare skin only tingle and burn at first,
but later little blisters will develop on your fingers. No
big deal - but it would have been better had I taken the
stuff more seriously.

Anyway, hope others benefit from the experience outlined here
in pictures. If you have questions, ask away.