Stubborn Stains

I have a rental property that is being put up for sale. I have gotten it into very good shape, but two things stubbornly persist to not improve. I would appreciate suggestions if you have them.

I have access Friday morning from 8-9:30, before the tours start. Tours will be from 8-6 Friday, Saturday, Sunday with contracts reviewed Tuesday. With tenants gone for the weekend, I can work on the property after the last tour. Delaying listing is not an option due to tenants’ schedules and critical time in our local market.

  1. Blackened caulk in tub. Grout is fine, but caulk has black areas, again. Worst case scenario I can replace it after the first day of tours on Friday, but currently tenants are on night shift and I have no access to the house. (Yes, legally I do, but I won’t put them out more than necessary.) I had replaced the caulk when we moved out 3 years ago, scrubbing down the area with bleach after removing and before putting new caulk down. In my search for ways to improve the black caulk, I read that I should have used vinegar, not bleach, to kill mold spores. Any truth to that?

I read ammonia is good to use, and can try that Friday night. (Tenants are gone for the weekend of blitz tours.) Any experience with this? Would the caulk still be stained even if the spores were killed by the ammonia?

I tried Scrubbing Bubbles, twice, which had worked well on our home tub, and it did improve it a bit, but not great. I tried gel bleach, which seemed to do nothing. Any ideas?

  1. Glass stovetop crud.

Minimized the 2 year build up with vinegar/baking soda/hot wet towel, scraping with scratch free pad. Improved, but not perfect, which is my preferred state, and the state these tenants received it in. One of the selling points of this home is the kitchen. We are asking a price that surprised me, and yes, it needs to be as close to perfect as possible. Also kept water on stove top while oven was in clean mode, which gets the water steaming hot, and then scraped again. Marginally better. Any ideas?


cross posted on Owning Rental Property, Real Estate Investing and Buying/Selling a Home Boards

  1. Since you want to quickly remove/lighten the blackened caulk, I would use pool chlorine on it. The bottles of Clorox in the store are around 6% chlorine. Pool chlorine is around 12%. The extra strength should help get rid of it unless you are talking clear caulk and the black mold is underneath the bleach can’t reach.

  2. Try Barkeeper’s Friend with a scratch-free pad.


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  1. Black caulk: Replace caulk. Get a bottle of “caulk remover”. Get two, they’re small. Spray it on (the consistency of body lotion), leave for 15 minutes, pull caulk off with a caulk remover tool. Total about $15/$20. The caulk remover spray breaks the chemical bonds and allows the caulk to simply lift off. Sometimes you will have to repeat on one small section where the goo didn’t get into the caulk for whatever reason.

Have a wastebasket and newspapers handy to put the old caulk on because it will be messy. Clean up with soap & water. Rinse well, because: apply new caulk. Spring for a $10 caulk gun and a tube of caulk. Squirt it into the crack, smooth with a smoothing tool if you’re fancy, with your WETTED finger if you’re not. Use an old credit card or something with rounded corners if you want really tight corners.

  1. Dirty glass stovetop: Don’t scrape with a pad. Get a razor knife that’s suitable for scraping stickers and such off a window. A single edge razor blade works fine. Change it out fairly frequently, an edge with a spur could scratch the glass. Scrape the glass top. Some glass tops have designs etched or “painted” onto the top, so test an inconspicuous bit to see if it scrapes off. If it does, do the rest with the knife but very carefully. Go back to the other scraper; now there will be a slightly larger height difference with the crud and a sharper edge and maybe the Dobie will catch it instead of gliding over it.…

The window scraper should be less than this Amazon example. Two hours for job #1, 1 hour for job #2. All materials available at any hardware store or home center.


When applying caulk, I first put painter’s tape on either side of where it will go. A time-consuming step, unfortunately, but it allows me to move quickly once I start caulking. Without tape, the “smooth” step gets messy.

2. Glass stovetop crud.
Razor blade to scrape thicker chunks off. I used regular metal ones that you get in a pack of 100 at the hardware store. I was very careful that I didn’t do anything that could result in a scratch, keeping a low angle and minding the corners. Possibly these plastic razor blades I see for sale might work too.

Then glass cooktop cleaner and a cotton rag. I think when I had a glass cooktop the stuff I used was Weiman cleaner. Went on as a white gel, and was a nasty grey/brown by time done scrubbing.


Glass stovetop crud.
Razor blade to scrape thicker chunks off.

Yikes! Metal blade on glass top? Never.

Even when minding the blade corners and keeping a low angle, too susceptible to scratching.

Here: Hard plastic scrapper blade.

We don’t have it, but if there is hard burned on crud, lay a rag soaked in just about anything. Leave overnight. Then use the plastic scrapper. Even use a light hammer to push thru if needed.

We always use the plastic blade, never metal razor. Too much chance for error, and a scratch is permanent.

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Yikes! Metal blade on glass top? Never.

Did it for 10 years, never a problem. Just be careful, and as I said change blades to make sure it’s sharp. The way to avoid it is to clean the glass top before the crud bakes on. With tenants you can’t monitor that. Actually, with me Mrs. Goofy couldn’t monitor it either, so the razor blade came out more often than I care to admit. But here’s a hint: I kept the pack of them in the junk drawer in the kitchen, not in the workshop downstairs.

Correction: I said leave the caulk remover on for 15 minutes. Should be for 3 minutes and not longer than 15 minutes . (I knew “15” worked in there somehow. I was just down in the workshop and pulled out one of the little bottles and read (magnifying glass) the instructions again.) The stuff works great, really!

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Best thing I ever did with a ceramic cook top was get a white one. I chose that because it was in a dark corner of the kitchen. The reality is that any burned on stuff gets cleaned every day because I can see it. Everybody I know with a black one ended up letting it get really bad before cleaning. I’ve used a scraper and Bar Keepers Friend for as long as I’ve had it.

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Thanks everyone. I had forgotten about the razor trick. Thanks for that.

I will be replacing the caulk after the first day of tours on Friday. I have done it often enough, so it shouldn’t be an issue. Won’t be perfect for day 1, but days 2 and 3 should get close to it.

Tempted to paint the entryway/stairway as well, (split foyer,) but at some point you just have to say enough. Have you seen the price of paint lately? More importantly, super high ceilings, with DH helping Youngest to move to another state that day, and we have an old dog at home who can’t be alone for long. Will just try to get the worst marks off with Mr. Clean sponge.

You guys are great!


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smooth with a smoothing tool if you’re fancy, with your WETTED finger if you’re not

I’ll add to this… for a water based or acrylic caulk, water works fine for wetting and smoothing. For silicone based caulks (which is what you should be using in a tub area), wet your fingers/tools with rubbing alcohol.


For silicone based caulks (which is what you should be using in a tub area), wet your fingers/tools with rubbing alcohol.

Interesting. I have always used the wet finger method and that has worked well.

I was on Amazon getting tools sent to me for these two projects when I saw the equivalent of pool chlorine. Supposed to work well, so I ordered it, taking the caulk removal tool out of my shopping cart. I really would prefer less work right now. The fact that I am buying from Amazon rather than Lowes should tell you how wiped out I am!


I have used Dap silicone bathtub sealer. In plastic tube. Tip can be cut for a fine joint line when needed. Water based. Easy to remove excess with a damp rag. Can make a very clean line.

Usually available at Walmart.

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2. Try Barkeeper’s Friend with a scratch-free pad.

Wow!! Seriously great stuff!

Trying the strong bleach tonight after the last tour.


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For that caulking, we have tried everything and Tilex does the trick. It is awful stuff! We open all the windows, especially if there is one in the bathroom, and turn on the exhaust fan. I hate breathing this stuff, so I hold my breath, run into the bathroom and spray the Tilex. Then run out of the bathroom. Leave it alone for maybe an hour. Then, hold my breath again and go back in and rinse the Tilex off the caulk with the shower sprayer.

Good luck!


Tilex has the same active chemical as household laundry bleach and pool chlorine except at a low concentration. I refill a Tilex bottle with laundry bleach.


…contracts reviewed Tuesday…

I hope you’re getting some good ones!