Kohler says “no” to: Magic Eraser, Comet, Bar Keepers Friend, Zud, vinegar… for cleaning its porcelain enamel cast iron

do not use comet zud bar keepers friend magic eraser on porcelain enamelWarning: This is a kinda epic story about cleaning products for your Kohler porcelain enamel cast iron bath tubs and sinks.

And please note:

Disclaimer: Here on the blog, as homeowners ourselves, we may try new cleaning products aimed at solving our own cleaning problems; if we think we’ve found something promising to consider, we may write about it. But, we are not professional chemists or engineers or home economists. So, please: Do your own research into these products and their suitability for your projects before trying them. More info in Terms of Use.


I recently wrote about my positive experience using a product called ROG1 to clean the dirty, slip-resistant bottom on my Kohler tub. I found ROG1 sold alongside another ROG product — ROG3, which is explicitly recommended on the Kohler website. The ROG1 worked like a dream to clean the eight years of baked on dirt on my bathtub’s slip resistant bottom. I am now a total convert, it’s changed my life, my bathtub is now easy to clean. But, keep reading, because as you will see, ROG1 is not explicitly recommended by Kohler, so I went to try and dig deeper.

Readers’ comments, too, launched me into asking Kohler some more question. You see, ROG1 is expensive — about $50 for the minimum order, which includes one bottle each of ROG1 and ROG3, including shipping. Not surprisingly, in their comments on my story, a number of readers balked at the thought of paying this price. As alternatives, they began to recommend other, much less expensive products they said that they had used effectively to clean the porcelain enamel on their cast iron bathroom fixtures, including: Magic Eraser, Comet, Bar Keepers Friend and Zud (my husband’s blunt cleaning instrument of choice). There also were mentions of baking soda. And of vinegar.

Hmmmm. I was suspicious about using these products on the porcelain cast iron. I have used these products on various surfaces in the past, and sure, they can lift the dirt like nobody’s business. But I thought: If Kohler was not recommending these well-known, potent cleaners, it might well be because they damage the finish on their porcelain cast iron bathroom and kitchen fixtures.

So I contacted Kohler and sure enough, they warn against using a number of these other, powerful cleansers because of testing and/or concerns that ingredients in them can harm Kohler’s shiny durable porcelain-enamel-on-cast-iron finish. Here is the text of our emails back and forth:

Pam to Kohler: In the comments section of my original story, a number of readers are saying how they use other products (not on your recommended list) including: Bar Keeper’s Friend, Zud, Magic Eraser, Comet, etc. My question to Kohler: Will these products ultimately etch the surface or destroy the high gloss on the cast iron or otherwise “damage” the cast iron finish?

Kohler PR responded:

Adam Horwitz, director of Kohler kitchen product marketing and cast iron development, tried to respond to the cleaning agents he saw in the comments:

Magic Eraser — Use sparingly only.  It can cause harm to the finish.  For example, you can use it to remove metal marks on a kitchen sink.  Another tip to remove marks from cast iron, scrub with a wine cork.  Not only will the sink get clean but you can enjoy a good bottle of wine.

Comet — Do not use.  It is an abrasive agent that will dull the finish over time.

Bar Keeper’s Friend — In our testing, we have found that Bar Keeper’s Friend can discolor the enamel when used over a period of time.

Zud — We have not tested Zud on our enamel.  However, we do see that it has similar ingredients to Bar Keeper’s Friend.

Pam to Kohler: What about home-made solutions using baking soda? What about vinegar?

Kohler PR responded:

Baking soda is fine since it is non-abrasive.  We have not specifically tested vinegar as a cleaning agent so we do not have data when it is used in a strong dose and left remaining on the sink.  Vinegar is acidic so it causes us some hesitation.  If homeowners are going to use it as cleaning agent, we recommend rinsing the area with water after use.

Pam to Kohler:  Why have you recommended the cleaning products you have recommended — and should owners of your cast iron fixtures avoid using anything but your recommended products and for what good reason?

Adam Horwitz, Kohler:

Kohler has done extensive testing of a variety of cleaning products and their effects on our cast iron products over time. We have listed the recommended cleaning products based on the results of this testing and advise that consumers avoid using other cleaners as they can dull or even damage the enamel coating on our cast iron products.

Pam keeps going, knowing she is probably being annoying and asks, “I’m curious about the active ingredients that are harmful”:

Kohler PR responds:

I am sure our development team could respond to a specific active ingredient question, but might not be able to address all active ingredients (there were many tests done, so the data is quite extensive).

Pam checks Kohlers list of recommended cleaners and realizes that Kohler has explicitly okayed ROG3, but not ROG1 — which is the ROG product Pam used on her tub. (Sorry to keep referring to myself in the royal third person — I’m trying to ensure the Q&A flows.) She asks Kohler about this…

Kohler checks and says:

ROG 1 is a cream cleanser (containing a mild abrasive) that is designed to remove stubborn stains.  We have not tested this cleaner on our enamel, but after looking at the MSDS, it appears to be safe (no acid).  ROG III [sic] is a liquid cleaner that is designed to clean and maintain the slip guard surface.  ROG 3 is the product we recommend on the Kohler Care & Cleaning website.

However, Pam is not done yet. On the ROG website, ROG1 (the cream cleanser Pam used) is described as “Kohler recommended” — but it is not listed explicitly as such on the Kohler website. So, Pam reaches out to the owner of the ROG product line and we talk about why this product is missing from the Kohler list. Then Pam sends Kohler another email:

Pam to Kohler: Thank you. Alas, I am not done yet… I reached out to the inventor of ROG1 and ROG3 and asked him why ROG1 had not been tested by Kohler. He said that, yes, it had been tested by Kohler — in the 1990s. Specifically, he said he worked with a man named [not included here, but provided to Kohler]. The inventor said that ROG1 was tested and approved then. Can you check this out for me? I just want to be as thorough as possible.

Kohler PR responds:

Hello Pam,

That’s interesting. I went back and double-checked, and our team says that we would have to retest with our current standards and knowledge. A test from the 1990s may be different from our current process. However, we have no immediate plans to retest it.

Hope this helps.

And there’s more…

Update on the labeling of ROG1:

Note, that in my subsequent use of ROG1 I saw that the label said it contained “Sulfonic Acid” — even though the owner of these ROG products says on their website, and has said on this blog in comments, that there is no acid in their products. So, I sent an email to ask about this discrepancy. Here is the exchange, and the company’s response:

I wrote to Vince Vallone, owner of the company:

This is Pam from Retro Renovation. I was just using ROG1 and noticed that an ingredient listed on the label is “Sulfonic Acid”. However, I don’t see this listed on the MSDS <– linked here. And you said this as a comment, “Yes Gina the ROG products are not caustic, no acids, many folks don’t realize the the grocery store and walmart caries many acid contained cleaners and will dull the bathtub over years, magic eraser has acid, 409 scrubbing bubbles and many more.”
Can you clarify?
 Thank you, Pam
 Vince Vallone, owner of the company replied via email, this is edited slightly because I asked one followup question and incorporated the response here:
Hello Pam
Hope all is well and we appreciate your follow up.
 The ROG 1 cream contains no acids.
After your e-mail….
Well we researched this and found the mistake and figured out what went wrong with the labeling.
We many years ago manufactured a deck and hull cleaner similar to the ROG 1 but it was called BCD’s deck and hull cleaner product named ROG 9
The ROG 9 Deck and Hull cleaner for the yachting, and boating industry this product had the sulfonic acid in the proprietary mixture and our bottle printer who prints the data on the bottle left this acid statement on the ROG 1 label, by mistake we never caught it till you mentioned it. Thank you, your new name should be retro-thour-ough-. LOL.
The ROG 9 was an experimental cleaner we tried years ago the formulas was to clean exhaust fumes on the aft side of the boat from inboard engines exhaust marks from the diesel engines and worked great but it never took off as expected so we stopped production on this product. Both were created around the same time, as we also had Glass cleaner and deodorizers, we no longer make.
But leave it up to you with your great journalism to find this mistake. Again thank you, we have now taken steps to remove that error from all future ROG1 bottles.
Thank you for looking at our mistake and we have now taken steps to remove this on all the ROG 1 bottles.

Pam returns solidly to the first person. Are you still with me?

Golly, I had no idea I would become the queen of clean on this research question.

Furthermore: I will relay a bit more of my conversation with the inventor of ROG1 and ROG3. He told me that his two cleaners include a “calcium reducer”. I am not a chemist, so I repeated back to him what I thought this meant. I said:

So what I hear you saying is that, it’s not really just dirt and scum that’s mucking up our bathtubs and tile and sinks, etc. It’s dirt and scum trapped and solidified by the calcium in our water. That is why companies like Kohler and others instruct — as part of instructions how to keep your tub/tile/shower clean — to ‘wipe down your tub’ or ‘wipe down your shower’ every time you use it. They want for you to get the water droplets (which contain dirt-capturing calcium) off these surfaces before they dry and begin to solidify all the gunk.

Yes, Mr. ROG1/3 told me. That’s it exactly.

I do not ever envision myself wiping down my tub, shower, tile, grout, sink, every time I use them. Do you? I think our grannies running those granny ranches may have, though!

My takeaways from all this:

  • Use Kohler-recommended products only. Readers: See Kohler’s page on the care and cleaning of their porcelain on cast iron sinks, tubs and shower bases here. This page includes their list of recommended products for cleaning cast iron — the glossy part, and the special slip-resistant bottoms. Some of these products are available at the grocery store, so they will be way cheaper than ROG1 and ROG3, so if you are still “searching” you could try the less expensive brands first.
  • Don’t use harsh cleaners or abrasives — read all the verbotens at the top of this story. Take note of Kohler’s warnings about the other products discussed at the beginning of this story. I am no chemist, but it sounds to me like anything “acidic” or “abrasive” can wreck your shiny pretty porcelain enamel finish, over time.
  • I still don’t think the grocery-store cleaners, even though “approved”, get the job done.  Me, I am done messin’ around any more with the household cleaners on Kohler’s list found at the grocery store. Kohler told me in this email that the ROG1 “appears to be safe (no acid)”, so I will continue using it, along with ROG3.
  • Note: No one is payin’ me to promote specific products. I got writing on this tangent because I was embarrassed, in a video I made, about the ick at the bottom of my bath tub. Opinions are my own, and I encourage you do to your own research.

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    • pam kueber says

      Joie, I do not know that there is an answer for this. Comet dulls the finish. If you want a lustrous finish, you need a new sink — and to NOT use abrasive materials (as described in the story) to clean it. Same for your tub!

  1. says

    Yes comet an abrasives will dull a bathtub and sinks, we have had several customers with the same problem, more than 2/2 got back the shind with the ROG1 as it is also a polish, and a few landmark hotels in South Carolina user the ROG 1 cream cleaner for not only bathtubs, sinks but polishing brass, so try it and good luck.
    Hope this helps
    Vince BCD owner who cares EDIT: Vince is the inventor/seller of ROG cleansers — Pam

  2. TammyB says

    When I got my Kohler porcelain sink 4 years ago, the secretary at my plumbing company gave me advice I have found nowhere else: Get rid of EVERY piece of stoneware, and never let it anywhere near this sink. You know the unglazed bottom? That is what scratches porcelain and once it’s srcatched, you’ll never get rid of the stains they absorb.

    I recently told this advice to a friend who is a potter AND who owns an old porcelain sink. Her response was “DOH! Of course it would scratch porcelain!!”

    So far so good for my own sink. I use only Kohler’s Cast Iron cleaner or baking soda (when the marks aren’t too bad.) Since I can’t get the cleaner at Home Depot anymore, I was looking around at other options. Thanks for your information, and I hope I have helped add to it for future sink owners.

  3. Scott says

    Very good tip Tammy.

    My dishes are all Boontonware and my pans are all stainless so nothing with rough edges ever goes in my Delafield and so far nothing has ever made a mark on it. A tiny dot of dishwashing liquid on a dish rag and drying with a dish towel has been all I’ve needed to make it sparkle.

  4. Liz says

    Question – are there any products to help remove old silicone from the edges of my 1950’s cast iron tub? I’m renovating and there are years of bad renovations on the edge of my tub that I’m not sure how to get rid of (especially without using anything abrasive).

  5. says

    Im Vince Vallone owner of slipprevention.com I deep clean bathtubs in major Hotels all over the US and Caribbean, I also invented the ROG chemical Co. And still taking care of all the Disney Orlando hotel properties.
    I am asked to do caulk removal and deep clean bathtubs every day the best thing to take silicon off is the flat edge razor blade yes the silver from the razor blade will mark the tub but the ROG one cleaner gets that gray silver scratches the blade makes, it gets them all off immediately that’s the best way to remove silicone, also plumbers across the US tell me the same, they use the blades and the ROG1 cream cleaner also use the one cleaner to get rid of the snake marks in toilets when they do the clean outs.

    • Kyria Christison says

      I recently bought an old cast iron tub with (apron instead of clawfoot) with the intent of refinishing it. I have done a ton of research on refinishing but then I caught a few minutes of a show with someone just giving theirs a good cleaning & thought hmmmm. We bought an 1876 house, gutting to the studs so my tub project was a long way down the list but after reading all of this I want to jump right in & try your suggestions I made sure the tub had no rust around the drain or faucet areas before I bought it. The outside & underneath definitely need redone but the only real issue was a few dis colored spots in the inside & some caulk around the edges. Vince….I almost wept when I got to your post about caulk removal LOL I am so hoping the previous owners weren’t too rough on this tub. I’m told it was just one owner (are t we always though) & Ill be able to bring some life back into the tub. I’m not as concerned about it being shiny & new looking. I like the fact that it’s old. I want to make sure it gets a good deep cleaning & preserve. Thank you so much!! I can’t wait to look around & see what else I can learn!

  6. Lisa Southerland says

    Pam, just found this portion of your blog. I have a chocolate brown kohler enamel sink. It’s only a year old and am very disappointed in myself that I allowed hard water stains to take the shine away. Contacted Kohler this week and they called me and told me to use White Vinegar straight. I did and it looks much better but it still doesn’t shine like it did! I’ll be purchasing ROG1 based on Vince’s comments that it will being back that shine!! Kohler also said to use Bon Ami and a wine cork to clean away the marks left from my sink grid feet! Will report how the ROG1 worked!!

    • pam kueber says

      Okay – but I am surprised at what Kohler told you. This contradicts what they told me. Be wary, readers….

      • Beth says

        I have also been confused by Kohler, as I have correspondence from them mentioning white vinegar and also Bar Keeper’s Friend as okay to use. I pressed them, as these cleaners are not on their recommended list. One rep stataed in an email, “Often we add
        the Bar Keeper’s Friend and white vinegar/water to the list as these are good products to use for cast iron and vitreous china products.” Reading this article makes me wonder why the folks at Kohler are deviating from their own list on the Kohler website. From what I have been reading, Bar Keeper’s Friend contains oxalic acid. One rep said to use it on stubborn stains, so it is not for everyday cleaning, but another rep made no such distinction. I would go by what Adam Horwitz told Pam. I love the idea of vinegar, but if it is acidic, I want to avoid.

        I do not believe Kohler has actually tested vinegar, from my questions to them. Also, it is unclear if they have actually tested Bar Keeper’s Friend in their 100,000 scrub test. Yet some of their customer service reps are recommending these products, which is confusing. Pam, do you think you could clear this up?

        Kohler also said to me not to leave ANY product on their slip-resistant surface for more than 10 minutes before rinsing the product off completely.

        • says

          Beth my name is Vince I’m the inventor of the safeguard for kohler co. the actual markings on the bottom of the bathtub or engineered and created by a type of sand blasting.
          I invented back in 1992 I also invented the cleaners that would clean that surface without damaging the porcelain the people you are talking to a kohler don’t even know who I am what happened back in 1992 as most people are retired or have passed away Jeff Collins is the only one still at kohlet but can answer these questions for you. I was asked by kohler quality control department who back then was Jeff Colins years ago to invent a safe cleaner Just remember no abrasive or any harsh chemicals especially anything with acid will damage the shine of the bathtub that’s why the ROG works great.
          pam has done a great job in her research. Hope this helps answer your questions

  7. Beth says

    Pam, I also want to point out Kohler’s current recommendations here: http://www.us.kohler.com/us/Cast-Iron-Baths-&-Whirlpools/content/CNT900123.htm

    Versus Kohler’s former recommendations here: http://www.us.kohler.com/common/pdfs/CareCleaning.pdf

    I asked Kohler about that second link, which I found by googling, and was told that was no longer current and to go by the new list. This older list includes Comet as a regular cleaner and Zud for rust removal. (See page 6.) Odd that they would still have it on their website. Anyone googling could find that information and mistakenly think it is current.

    I also asked about ROG 1 and was told it was not approved; only the ROG3 is approved. My thoughts are perhaps the composition of the slip-resistant tubs has changed in the past 10 or 20 years. Kohler doesn’t list it, so I personally would not use it. From the two lists above, Kohler appears to revise its recommendations periodically, as some products previously listed are no longer listed.

    • pam kueber says

      Yes, Beth, in this story you can see I asked Kohler about ROG1. Kohler told me (and this is also in the story above):

      “ROG 1 is a cream cleanser (containing a mild abrasive) that is designed to remove stubborn stains. We have not tested this cleaner on our enamel, but after looking at the MSDS, it appears to be safe (no acid). ROG III [sic] is a liquid cleaner that is designed to clean and maintain the slip guard surface. ROG 3 is the product we recommend on the Kohler Care & Cleaning website.”

      • pam kueber says

        Beth, I feel like I have beat on this story as much as I’m going to. Don’t use acids. Don’t use abrasives. Read this story – in which I received recommendations straight from Adam Horwitz, director of Kohler kitchen product marketing and cast iron development.

        Read all this stuff… talk to Kohler yourself… and make your own decisions…

  8. pam kueber says

    Peoples, I am closing the comments on this story because the same things keep coming up over and over again.

    Read the story above, in which I received recommendations straight from Adam Horwitz, director of Kohler kitchen product marketing and cast iron development.

    Talk to Kohler yourself.

    Make your own decisions.