If the mildew is not coming off, then it has stained the surface. This will require you to repaint the walls or ceilings. If its on the caulk around the edge of the tub, you will need to scrape it off and replace. Once the mold gets into the surface of the porous materials you can do little to change the appearance. of the stains.
To prevent this from happening again you must keep a window open when using shower or tub, yes even in cold weather, Or install a fan. If you have a fan installed already, you need to check its operation to see that its working. Take a few squares of toilet paper and place it against the fan cover when its running. If the paper sticks and stays, your ok, if it falls down or sags you need to upgrade your fan.
In real bad cases of mold development on ceilings, check your insulation in attic above. The cooler attic temps in winter months combined with poor insulation allows water to condense on the ceilings whenever the shower or tub is used. This extended moisture condition from this causes mold to develop quite quickly.
thank you so much for will definitely have to replace the caulking..
Very helpful info......thanks . my ceiling fan needs to be checked..I will do this, however i always leave the window open anyway. But hubs does not. Didnt know this about how to check fan to see if it is working.
there is exhaushed fan that has sensory to turn on itself from humidity in ur bathroom ceiling. saw one @ home depot that had to order. that was several years ago. do not know if home depot still has it. can check online.
I recently installed a fan and timer switch for a client. The switch has multiple setting for 10 min, 20 min 30 and hour....this way it can run after you leave the room and turn itself off.