How to effective clean and prevent pink mildew/mod

January 4, 2024 8:24 PM

There are dots of pink mildew/mold on the painted ceiling above the shower/bath. There is no vent or fan in there, and since I rent, I cannot install one. How do I clean the ceiling & prevent this from happening again?

I want to be able to get rid of the stuff without damaging the ceiling paint. (The ceiling paint is the cheap kind which is not my choice). I also want to prevent mildew and mold issues from happening again, if possible.

What I do now:

keep the window cracked while I take a shower and for 10 minutes after

keep the bathroom door open always

use daily shower cleaning spray on tub and tiled shower walls

Extra info: I used to use a squeegee to get moisture off the tiled shower walls and tub, but that caused issues with the grout. Then I started using a towel. Now I'm not doing that because I wasn't sure whether that interfered with the daily spray since the directions said to spray right after showering.

posted by Four-Eyed Girl to Home & Garden (18 answers total)

If all you have is a window, it takes a lot more than 10 minutes to vent the humidity.
posted by Dip Flash at 8:39 PM on January 4 [6 favorites]

1) Scrub off as much of the mildew as you can. Bleach the ceiling using a sponge mop and bleach water. Wear swim goggles! It will drip.

2) Get the bathroom as dry as you can. In your case, this will mean putting a fan blowing out the window and another blowing in from the door, to effectively move air. You can also try a strong space heater.
3) Paint the ceiling and other paintable surfaces with Kilz, let it dry. Then add your other color if applicable.

4) Every time you shower, do your spray (you can probably squeegee off water first, then spray) then turn on the space heater and fan until the bathroom feels dry, which could be overnight.

What your landlord needs to do is address the no-fan situation and probably replace some of the shower/bath surrounding materials. If the grout is having issues with a squeegee, they probably need to redo the entire shower surround for moisture issues (grout should not be vulnerable to squeegee.)
posted by blnkfrnk at 9:27 PM on January 4 [3 favorites]

Bleach is less effective at removing mold from porous surfaces like the ceiling. Clove oil though is quite effective. Don't use it straight, it needs to be quite dilute, see link for amounts. When diluted should not cause any visible staining but I'd do a test spot anyway.
posted by dragon garlanding at 9:58 PM on January 4 [1 favorite]

I had a similar problem once and concluded that it was, in fact, nicotine bleeding through the walls. For years before I lived there, the previous tenant smoked exclusively in the bathroom. Regardless of the source, I would suggest you do the prep work that blnkfrnk suggests above, then get a small can of KILZ paint and paint the ceiling.
posted by eleslie at 2:23 AM on January 5

It's probably not mold:

This pink mold you've found growing on your shower curtain, or in your toilet is not actually mold at all; in fact, it's a Gram-negative bacteria that is scientifically known as Serratia marcescens.

The pink colour is from a pigment (prodigiosin) produced by Serratia marcescens under the right growing conditions.

Serratia marcescens is commonly referred to as “pink mold” or “pink mildew” but it is bacteria causing those irritating pink stains in the bathtub and on your shower head.

And it has been considered harmless enough to be chosen to simulate anthrax attacks in secret bioweapons vulnerability and response tests carried out over wide areas of the US from the late 40s through the 60s.

I have often wondered whether the now ubiquitous pink stains in people's bathrooms were much of an issue prior to those tests, but I haven’t been able to find any research on the question.
posted by jamjam at 3:42 AM on January 5 [5 favorites]

I've always found radiant heaters to be far more effective than space heaters at keeping bathrooms free of heavy steam and their surfaces free of assorted growths.

If you can work out how to position a box fan so as to blow a stream of air outward through the window then that will help a lot as well, especially if there's another open window somewhere outside the bathroom for replacement air to be drawn in through. If you don't have room for a box fan, even a hair dryer with all the heat turned off is better than nothing.

Having the fan maybe a metre inside the window will work better than trying to mount it into some kind of window plate, because most of the additional air entrained by the main stream will then come from inside the room instead of circulating uselessly outside.
posted by flabdablet at 4:32 AM on January 5 [1 favorite]

Response by poster: Re-painting is not an option because of the landlord.

The landlord has re-grouted 4 times. They’re not doing it well, but that’s another thing out of my control. I’m not allowed to do that myself.

Would a dehumidifier help?
posted by Four-Eyed Girl at 4:39 AM on January 5

Yes, but it takes a lot more energy to collect all that water vapor into one little liquid pool than it does simply to blow it all out of the room with a full air exchange, and probably more time as well.
posted by flabdablet at 4:42 AM on January 5 [1 favorite]

Can you keep the window open longer? I used to have a 2 family in a very safe area; tenants would close the window and with 3 showers a day, sheesh. The windows had a special lock so you could leave it open 4 inches; look in to something like that. While the window is open, use a fan pointing outside. When the window is closed, use the fan pointing to the rest of the apt. and maybe a small heater with a fan. A dehumidifier will help a fair bit.
posted by theora55 at 7:06 AM on January 5

In Germany they open the windows fully (in all rooms) ten minutes in the morning and ten minutes in the evening if they have this problem. But they have special windows that help air flow, maybe your bathroom window ten minutes with a fan?
posted by catspajammies at 7:11 AM on January 5

Get a box fan or small fan and run it during/after showering. Open the door and window and use it to move air - that will pull out the humidity. There are also removable window fans, they work great and are super easy to put in and remove - assuming your window opening is the right size.
posted by DoubleLune at 7:33 AM on January 5

You deserve to live in a mold free environment - and in many jurisdictions that is also your right. I have forced landlords* to fix mold issues as our local government has very strong opinions about this issue. One remedy available was withholding rent (with notice and timeline and registered mail and et etc etc) but just knowing what our rights were turned out to be sufficiently motivating.

In the meantime you need to move that moist air out of the bathroom. I've been impressed with our Vornado products and wouldn't hesitate to recommend something like their TRANSOM window unit for forcing more air movement.

As for fixing how the space looks - if you want to avoid confrontations with your landlord or you live somewhere with limited rights, well I would just paint it anyway. Seriously. I've done it and landlord did not notice. The equipment cost is low - and with some tape and a sheet you will certainly end up with as good a finished product as whoever the landlord contracts the work to. Modern paints shops will be able to accurately match what the color is (or supposed to be - you might need to sample another room). And then you can use proper product for the mold situation - I've used Zinsser.

*turns out knowing what your actual rights are is contagious - in our building it quickly snowballed into nearly a quarter of the units requiring remediation. There was a blind lady who got to stay at a hotel as our landlord had let it get so bad. And then some or friends also were able to push theirs for fixes.
posted by zenon at 7:44 AM on January 5 [1 favorite]

I know you said repainting is not an option, but a layer of Kilz absolutely has to be put on there. It's a health and safety concern, not aesthetic. It should have been applied when the shower was first installed and/or painted in the first place. If the landlord won't do it and also refuses to let you do it (which would be WILD), just do it yourself anyway as blnkfrnk described and keep it on the down low.
posted by LKWorking at 11:37 AM on January 5 [1 favorite]

Yes, just smack it with Kilz. How is the landlord going to know/why is the landlord going to care? (Apologies if there are reasons the landlord will both know and care. I did this in my apartment with the "no paint" clause in the lease and they neither knew nor cared, but they were pretty hands-off landlords. I also regrouted the tile in the 1940s kitchen in an attempt to save it because I knew if it were left to them, they'd snatch it out and replace with some gross "woodgrain" formica garbage.)
posted by Don Pepino at 1:00 PM on January 5 [1 favorite]

I live in an old Victorian with no vent fan and had a similar issue that I really struggled with. What finally worked for me was the advice from my contractor: first cleaning/scraping then going over the entire bathroom area with Mold Killing Primer before re-painting. Don't skip the mold killing primer!! Then I purchased a dehumidifier like this one. I start it as soon as I run the shower or bath, close the toilet lid and put the timer on 2-4 hours, depending on the season. I haven't had a single problem since then. Don't skimp and get one of the tiny ones - they just don't work as well and don't make it dry enough. Also, get one with a timer.
posted by crayon at 1:15 PM on January 5

Dehumifiers are great, and they are also very efficient heaters when you pour the water they accumulate down a drain, optimally before it reaches room temperature.

But all the things they keep from growing on your walls, curtains, and fixtures will also happily grow on the coils of your dehumidifier, and those tend to be hard to clean. I’ve been waiting years to see a dehumidifier that incorporates a hdden germicidal lamp in the airstream before it hits the coils, but there must be design challenges I’m not aware of.
posted by jamjam at 2:41 PM on January 5

Unless you live somewhere where like southern california where it's like 65f+ and low humidity even in the winter, opening the windows to air out the bathroom sucks at drying it out and preventing things like this. I've done the dehumidifier thing before* but honestly what's worked great is just sticking a fan in the doorway, and cracking the windows in the rest of the place. This knocks down condensation brilliantly, and only mildly humidifies like, an entire medium sized apartment. I genuinely think a lot of what makes the humidifier work well is the air circulation around the room, as the weak/slow fan models seem to be awful at this too.

I had no bathroom fan for months during a one person remodel and even after i put one in, i kept the doorway fan and absolutely swear by it. And i mean like, a tiny fan like this, set on the lowest speed. You don't need restaurant hood level airflow here. I would only bother with a dehumidifier if there was a real concern about steaming up the rest of the house a small amount because it was too cold out to crack the windows, etc.


*(and yes, you need one of the real compressor type ones, the mini countertop ones are junk and a waste of money)
posted by emptythought at 11:08 PM on January 5

opening the windows to air out the bathroom sucks at drying it out and preventing things like this

Even if the rest of your living space is humidity-controlled by air conditioning, replacing a bathroom's worth of guaranteed-100%-humid-plus-droplets bathroom air with air drawn in from outside is going to give your AC a lot less work to do than venting your bathroom internally.

My own bathroom is completely capable of setting off the hallway smoke alarm if somebody showers with the door open.

A cheap box fan blowing outward through a window, with both the bathroom door and a window elsewhere cracked open to admit replacement air, will vent a bathroom way faster than relying on diffusion or random breezes through the same window. A typical box fan will clear a bathroom of all visible steam within five minutes, and if you run radiant heating in there as well, the walls and ceiling will be dry in under half an hour (radiant heating is almost completely unaffected by air movement, unlike space heating).

If you've got no radiator and you'd rather rely on a dehumidifier to get the walls dry, venting through the window with a box fan for five minutes before starting the dehumidifier will give it a huge head start. And having closed the window and started the dehumidifer, leaving the box fan running just to stir the air more aggressively than the dehumidifer will do alone will noticeably speed drying too.
posted by flabdablet at 11:36 PM on January 5