"TomR" wrote in :

I am going to meet with a friend of mine in a couple of hours to see if I
can help him with a clogged/slow drain issue. I haven't seen it yet, but so
far, he seems to be saying that it is mostly a bathtub (and maybe a sink in
the same bathroom) that has a slow drain problem. I think he said he tried
to unclog it before but had some problems with it, and he wants to know if
by looking at it if I could figure out how to correct the problem.

Of course, we'll be doing the routine stuff -- using a plunger, a snake, one
of those plastic hair-cleaning gadgets, maybe Liquid Plumber, etc.

But, I was wondering if anyone has ever tried using acid -- probably not
something too strong, but maybe diluted acid or whatever.

NOT NOT NOT if you've tried Liquid Plumber or Drano first!!! NEVER EVER mix alkali and
acids!

When I was in junior high school, one of our shop teachers learned about that the hard way.
Some knucklehead student dumped a bunch of sawdust down the sink drain in the wood
shop, which of course clogged it. Teacher poured some Drano in there. No effect. Next
thing the teacher tried was muriatic acid. The [entirely predictable] reaction with the alkali
that was already there blew the acid back in his face. He wasn't wearing safety goggles,
either. Fortunately for him, the wood shop was next door to the boys' locker room; couple of
students dragged him in there and threw him in the shower -- the doctors said that's what
saved his sight. But it wasn't quick enough to prevent some really horrible scarring.

And consider this: why do you suppose that commercial drain cleaning products such as
Drano, Liquid Plumber, and so on are alkaline? If acids worked better, wouldn't these
products use acid instead?