I just discovered what I assume is mold on my window frame in the kitchen/living room (quite high humidty, but the window has been open a lot and our fan is going 24/7). Now, I've been told that dealing with black mold is dangerous, my landlord however looked at it and said it can easily be dealt with with bleach. After googling this I'm still not sure if I can or can't deal with this myself, some say I should get him to get someone to do it professionally, others recommend everything from bleach to special paint. What is the right way for me to deal with this?

Mold on the left side Mold on the right side

  • There are many varieties of mold. Many of them appear black, and most are harmless outside of being cosmetically undesirable. I'd start by just wiping the stuff away with detergent and water and see if it regrows,before bothering with anything more aggressive.
    – keshlam
    Apr 20, 2016 at 15:25

3 Answers 3


That looks pretty bad. Don't use bleach, use a purpose-made mold killer product. I like Mold Armor, myself. Be careful with these products. They're super caustic and you could probably hurt yourself if you drink them or don't have good ventilation.

  • Aside from that stuff being rather aggressive, any other health concerns that I should be aware of? With regards to the actual mold, not just the cleaning product itself.
    – JustSid
    Apr 20, 2016 at 16:40
  • Why not use bleach?
    – Dave
    Jul 8, 2016 at 1:33
  • Most household bleach products aren't very powerful and all the plain water in them can seep into wood, nourishing hidden mold under the surface.
    – iLikeDirt
    Jul 8, 2016 at 17:40

I think that the landlord is responsible, but sometimes it's necessary to do things yourself... that depends on your living/renting situation.

Household (5%) bleach (dilute 1/2 cup bleach : gallon water) will absolutely work. The black mold is probably Aspergillus niger, which often produces something called aflatoxins, which can cause cancer. But the danger involved with cleaning it off of a few windows is overrated compared with chronic exposure from living with it, eating it, or cleaning it up on a daily basis (ie., people who clean or remove mold for a living). But if you are concerned, use a dust mask.

Mildew resistant paint would be a good idea, after you clean it. But more importantly, the reason for the mildew is moisture; maybe it's from humidity/condensation, but usually the problem is that the window is getting rained on, and water is collecting on the sill. Preventing mold should start with weather protection. If high humidity, is the issue then a dehumidifier should be used.

  • I'm mostly at concern for my health here, I don't mind cleaning it up if I'm not at risk for something. The internet seems to be full of FUD in that regard. And yeah, definitely moisture, it's an old single sided window. Although the humidity is at around 45-50% which seems to be what the UK government recommends. But yeah, since it's in the kitchen there have undoubtedly been peaks in humidity from that alone.
    – JustSid
    Apr 20, 2016 at 16:39
  • @justsid I see. Well, a dehumidifier should be helpful. Humidity from cooking should be vented with a hood. Often, clothes dryers are blamed for humidity, so be sure to check the vent hose for lint. Apr 20, 2016 at 17:17

I had mold in the basement bathroom. We installed a window which can be opened, a small humidifier, and cleaned mold with bleach. Advice for bleach, I emptied window cleaning spray container and sprayed bleach rather than using a cloth or something else. Works like magic. No more mold.

  • In the spray bleach, did you use 100% bleach. Or did you mix with water? How many parts bleach, water? Thanks.
    – Rhonda
    Jan 20, 2018 at 16:08
  • Used 100% bleach. No water added.
    – Branka
    Jan 21, 2018 at 17:08

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