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LISAinTN 03-31-2009 06:16 PM

Refinishing a Clawfoot Bathtub
Hello everyone,

I'm new here and have a question about refinishing a clawfoot bathtub. I have spent about 4 hours on the internet today and haven't answered my own question. :rolleyes: I figured I'd seek out a forum where someone may be able to help. :)

I live near Knoxville, TN and I have called about 4 places about refinishing this tub. Everyone I have talked to will do a process which they call a "two part acrylic polyurathane" finish. They offer only a 5 year warranty and say it will last 10 - 15 years! I want a new porcelain finish so it will last another 50 - 100 years. LOL So my question is, doesn't anyone refinish a tub with old fashioned porcelain? Is this just an obsolete process now? I just really prefer the old ways of doing some things as they just seemed to last longer then modern day products. I would appreciate any help/opinions. Thank you kindly.


Nestor_Kelebay 03-31-2009 09:15 PM


So my question is, doesn't anyone refinish a tub with old fashioned porcelain? Is this just an obsolete process now?

No, it's not at all obsolete, and new powder coatings are being developed all the time. In fact, you can even get teflon coatings baked on at most shops.

Really, what the problem here is that you don't understand the powder coating process well enough to realize that it simply CANNOT be done in a person's house. Lemme explain it:

The porcelain enamel on your old bathtub is not applied like paint. Porcelain enamel is applied by the same process as "powder coating". In this process, a mixture of synthetic plastic particles and coloured particles (called "pigments") are electrostatically sprayed onto a metal part. That is, the metal part is charged positively and the gun spraying out that mixture of particles is negatively charged. Thus, the particles coming out of that gun are also negatively charged so that they coat the positively charged metal part fairly uniformly. That is, they are attracted more strongly to the more positively charged areas of the metal part where the coating is thinnest, so this process tends to coat the metal uniformly with powder.

That coated metal part is then baked in an oven for anywhere from half an hour to 4 hours at 350 to 1200 deg. F. During this time, the synthetic plastic particles melt and flow together to form a continuous film over the metal part with the coloured particles suspended inside it much like raisins in raisin bread. But, just as importantly, the plastic used in the resin particles "cure" at the elevated baking temperature. That means that chemical bonds form within and between the plastic resin particles to make the plastic heavily "crosslinked" with chemical bonds, and that results in the coating being much harder, stronger and resistant to heat when it cools.

When the metal part is taken out of that oven it is said to be "powder coated", but that's a misleading description to anyone not aware of the process. The coating was only a powder prior to baking. Now it's a solid film that's very much harder and more durable than air dry coatings like epoxy paints, two part acrylic polyurethanes, moisture cure polyurethanes, etc. And, therein lies the problem. These field applied coatings simply can't match the hardness and durability of powder coatings, and you need that high hardness and durability to provide a 50+ year lifespan on a bathtub.

Steel and cast iron tubs come powder coated from the factory. But, to recoat them you need to sand blast the old powder coating off and powder coat them again. This could probably be done by any powder coating shop in your town, just look under "Industrial Coatings" in your yellow pages phone directory. However, the cost associated with removing the old tub, sand blasting it, recoating and baking it, and then reinstalling it would be more than the cost of installing a new steel or iron bath tub.

So, no one offers an in-house powder coating service because of the impracticality in doing it. How would they heat up your cast iron tub to 400 degrees without burning your house down? THIS is why you've come up empty in finding someone to powder coat your bathtub.

You don't need to know the rest:

Generally, if the baking temperature is less than 500 degrees F, the coating is simply referred to as a "powder coating". However, if the baking temperature is above about 800 degrees F, then the resulting coating is generally called "porcelain enamel". That's cuz the coating itself resembles more of a ceramic material. Porcelain enamels are also often referred to as "ceramic coatings". Generally, the higher the required baking temperature, the harder and more durable the coating will be.

There are several examples of powder coatings in your house. For example, the side panels on your stove are only painted, but the cooktop itself and probably the front panel on the oven door will be powder coated. That's cuz these parts will get much hotter than the side panels when you're baking something, or self cleaning the oven, and powder coatings stand up to high temperatures much better than field applied coatings do. Field applied paints would soften up when they get warm, and sliding a pot across that warm cooktop would scratch up the paint.

The interior surface of your hot water heater's tank is powder coated to protect the steel walls of the tank from corroding.

And, probably the hardest and most durable powder coating in your house is the blueish gray glass-like coating on your stove's oven walls. That coating was baked on at about 1200 deg. F.

You can learn more than you need or want to know about powder coatings and porcelain enamels at:

LISAinTN 04-01-2009 07:30 AM

Hi Nestor,

Thanks for the reply. Actually, I do understand the process, (although not in that much detail) but I know it can't be done in my home and I planned to take the tub where it needed to go to be sandblasted and recoated. My problem as I said is that I can't find anyone to do it. So far I've only called people who refinish tubs as I thought that would be the obvious way to go. I'll see if I can locate anyone through the "Industrial Coatings" section in the phone book. That was my problem is knowing where to look besides bathtub refinishing. Thanks.


LISAinTN 04-01-2009 09:22 AM

Well, after another 2 hours on the telephone this morning, apparently the process is obsolete, in my area anyway. lol Everyone I've talked to says nobody does this process anymore. So I guess I need to decide if I want it refinished in some cheap process or if I should just buy a new tub. I'll ponder it for awhile.

LISAinTN 04-01-2009 12:59 PM


I have a question for you. I just found someone right down the road from me in the boonies that does powder coating, but it's not porcelain. He said.....(Okay, this is in blond terms and not exactly what HE said. LOL) ......He will sandblast the tub, but not to remove the old porcelain. Just to etch the surface. (I imagine for better adherance for the next step in the process.) Then the powder coating, which he said is a powder pigment, is sprayed on and then baked at 400 degrees. Here's my question: How durable is this process? He said it was not as durable as porcelain. And he also said not to clean it with things like steel wool and Comet, which I already figured. Do you think this process will last a long time? Or will it be like all the other people I've contacted who've said it has a life expectancy of 10 years. Any help/advice would be appreciated. Thanks.


glennjanie 04-01-2009 06:21 PM

Welcome LisainTN:
I just returned from your area Monday and wish I could have stayed. Dolly is as pretty as ever and we love the family atmosphere in Pigeon Forge.
I recently saw a show on the Discovery Channel that showed how American Standard coats a cast iron tub (for the 50 year finish). The formed the tub, took it out of the mould, and while it was still cherry red, they sprinkled the porcelain on with a scoop shovel (requires lots of experience and artistry). When the tub cools the finish is as hard as glass.
Your local powder paint man is the best finish you can get in retro, but tubs and all bath fixtures should not have bleach, abrasive cleaners, steel wool or even tile cleaners used on them. Each use of these things breaks down the porcelain a little more. Even the toilet will show signs of dulling after a few years of strong cleaners. I know, we want to clean and sanitize the surfaces, so we like the strong stuff. Industrial chemical suppliers even mix acids into their cleaners; a BIG no no.
I would go with the local guy.

Nestor_Kelebay 04-01-2009 09:23 PM

Lisa and Glenn:

In my view, a powder coated tub will stand up much better than any field cured coating like the two part acrylic polyurethane that's being offered by others. The question is: How is he going to bake that tub at 400 degrees without removing it from your home and replacing it, and if he does that, it makes more sense to just install a new tub, doesn't it?

Also, if he's going to sand blast the tub anyway, WHY NOT sand blast all of the old porcelain off and powder coat the whole tub? I my opinion, the existing porcelain will not be powder coated (or powder coated very thinly).

Powder coating will give you a more durable coating than refinishing the tub, but I don't see why he can't remove all the porcelain (at least on the inside of the tub) and powder coat the whole interior.

Maybe keep looking. You SHOULD be able to find plenty of shops in Tennessee that do porcelain enamel coatings.



Your local powder paint man is the best finish you can get in retro, but tubs and all bath fixtures should not have bleach, abrasive cleaners, steel wool or even tile cleaners used on them. Each use of these things breaks down the porcelain a little more. Even the toilet will show signs of dulling after a few years of strong cleaners.
While I'll agree with you on the abrasive cleaners and steel wool, I have to take exception with the bleach and tile cleaners.

I own a 21 unit apartment block in Winnipeg, Manitoba, Canada and have been using bleach to remove stains from linoleum, 100% Olefin carpets, and plastic laminate for over 20 years now. I REGULARILY clean mildewed silicone caulk after tenants vacate by having it in contact with a bleach/talc slurry for several days. I have never noticed any deleterious effects on the olefin carpets, linoleums, laminates or porcelain enamels as a result of using bleach on them, even for extended periods.

I also clean stains out of the acrylic floor finish on my vinyl composition tile floors using bleach. The bleach will clean the stain off the acrylic floor finish without dulling it's gloss. It seems to me that if the bleach was harming the floor finish, the first thing to go would be the gloss.

And, of course, I've remove heavy nicotine staining from latex painted walls using bleach, without harming the paint. I simply rinsed the bleach solution off the walls, allowed time to dry and painted over them. (I don't know how many "paint people" there are in this forum, but good quality latex paint is made out of acrylic plastic. That is, good quality latex paint and good quality grout sealer are both made out of the same plastic we call "Plexiglas".)

The reason why phosphoric acid is commonly used as a general purpose bathroom cleaner is that it cuts through soap scum like a knife, but won't attack chrome plating. In my case, all of my bathrooms have ceramic tiled walls around the bathtubs, and the grout lines are sealed with an acrylic grout sealer. When tenants vacate, I use a phosphoric acid based toilet bowl cleaner on the ceramic tiling around the bathtub to clean the soap scum off of it, and I have been doing that for over 20 years now.

If it did any harm to either the tile, the tub or acrylic sealer on the grout lines, I wouldn't do it.

Sorry, but we're going to have to agree to disagree on this point. "Strong chemicals" that may dissolve and discolour some materials often have no effect whatsoever on other materials. This is why you can buy muriatic acid in plastic jugs. The plastic the jug is made of is unaffected by continuous and prolonged exposure to hydrochloric acid. And, before the world was flooded with plastic, hydrochloric acid was stored in glass bottles:

If hydrochloric acid doesn't harm the glass bottle, I expect it wouldn't harm real porcelain like a toilet, bathroom sink or even glazed ceramic wall tiles. It might dissolve the grout between the wall tiles, but it shouldn't harm the surface of the wall tiles.

Despite how "strong" some chemicals are, it doesn't stand to reason that they harm everything they come into contact with. Often, they have little or no effect on materials.

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