On Sun, 24 Mar 2013 17:29:42 -0400, Joe Gwinn
wrote:

In article , Ed Huntress
wrote:

On Sun, 24 Mar 2013 16:00:16 -0400, Joe Gwinn
wrote:

In article , Ed Huntress
wrote:

On Sun, 24 Mar 2013 15:28:07 -0400, Joe Gwinn
wrote:

In article , Ed Huntress
wrote:

On Sun, 24 Mar 2013 14:47:18 -0400, Joe Gwinn
wrote:

In article , Ed Huntress
wrote:

On Sat, 23 Mar 2013 19:38:08 -0400, Joe Gwinn
wrote:

In article , Ed Huntress
wrote:

On Sat, 23 Mar 2013 12:37:28 -0400, Joe Gwinn

wrote:

again. Thanks again.

Welcome. Good luck. Keep us posted.

[snip]
Joe, problem solved. Thanks for your help.

It was the result of a change in detergents. About five months ago my
local supermarket stopped carrying Finish powder, so I switched to
Cascade. I didn't think that could be it, since the Cascade seemed to
work fine for all those months.

But I talked to another friend who used to be a repairman for Sears.
He said it was almost certainly the detergent. So I bought some of
those fancy Finish capsules. I've run the dishwasher twice since then
and everything is sparkling clean. It even seems to eat off the lime
from stainless pots that already had a coating. I saved a couple
without giving them the vinegar treatment, just to see what would
happen.

Finish? That was the stuff I was trying to remember, specifically
Finish Glass Magic. Finish Quantum PowerBall too. The magic
ingredient is phosphate.

Finish, used to be Electrosol. I used the Finish Quantum packets.



So that appears to have been it. Now I can relax and fix the tub
drain
in my bathroom. d8-)

Boiling lye, to dissolve the hairballs?

Not the problem. The problem is 90-year-old cast iron pipe that I was
having to auger out about once a month. The lye quit working 10 years
ago. Sulfuric acid stopped working 5 years ago. It's time to bite the
bullet.

I used a cast-iron pipe cracker and I've cracked the pipe at both
ends. Now I have to work fast and replace it with PVC. If my wife has
to bail the tub after showering during the work week, my ass is grass.
g

The PVC pipe is noisier than cast iron, so you may want to wrap it in
something to keep toilet-flush sounds down. At the very least,
vibration isolate it from the joists and studs.

Ok, but this is a horizontal stretch that drains only the tub.


Actually, what I do is to put a pile of straight lye in the drain and
pour in about a cup of water, and let it work for awhile. Don't forget
to rinse it all away later.

That's the way I did it. I was using a pound per shot at the end,
before it just quit.


Joe Gwinn

I was getting really good at that, buying my lye in bulk from these
guys:

http://www.essentialdepot.com/

They have frequent sales.

Good source of supply. Thanks.


Thanks to the sulfuric acid, my next job is to re-finish the tub with
two-part polyurethane. Ugh. d8-(

This cannot be a vitreous enameled cast iron tub, which would laugh at
anything save hydrofluoric acid.

Joe Gwinn

Yes, it is a vitreous enameled cast iron tub, probably 60 years old.
And yes, the sulfuric flaked the enamel off the surface. It's like
white sand in the bottom of the tub after you take a shower. And it
wore right through at the drain.

Probably just wore the enamel out, over the decades. Does a puddle of
water sit there, not quite able to drain?

It would, if I didn't bail and sponge it out. But no, I don't leave
water standing in the tub.

Does the faucet drip? That too will cut a groove in the enamel.


Glass does dissolve in
water, but very slowly. This will render the glass porous and fragile.

So, after the recoat, make sure that the tub drains completely, leaving
no puddles.

I've never recoated a bathtub, so I don't have any information on the
best approach, but I'd have to think that two-part epoxy is the best
way.

Supposedly the two-part polyurethane is much more abrasion-resistant
than epoxy. That would agree with current treatment of
high-performance boats. I see that's what the quality refinishers are
using, and someone -- maybe Sherwin-Wiliams? PPG? makes a kit just for
that purpose. You apply it with a fine sponge roller. The spray is
highly toxic.

OK. Sounds like Imron.


The key is to get things *really* clean - even the slightest soap film
will totally defeat adhesion. One needs to use an acid that will
chemically destroy the soap, especially the non-sodium soaps that form
the core of soap scum, then neutralize the acid, etc. And follow up
with Bon Ami and lots of elbow grease.

Joe Gwinn

I'll first sand it down a bit with a vibrating sander, I think, but
I'll be checking into the recommended prep methods first. I realize it
could be troublesome.

I would *not* use a power sander, for fear of accidentally cutting
through to the iron.

I'd use wet-dry sandpaper on a rubber block, wet. And a bright light
not in your eyes, so you can see what's going on.


I appreciate the tips, Joe. I hate to screw these things up; there
isn't time to do it twice.

Yeah. I'd look up the paint manufacturer's instructions on cleaning.
Do they offer this paint as suitable for bathtubs? If so, they will
have detailed instructions.

Joe Gwinn

Yes, it's made for bathtubs. I'll be very careful and make sure I have
instructions for doing it. I'm kind of attached to our old tub, and I
don't want to go three or four days without a shower because I screwed
it up. I'd feel like I was back in France, but without a bidet. d8-)

(Actually, I'd just walk down to the YMCA and shower there. I've
planned for emergencies.)

--
Ed Huntress