black spots around window frames

Hello,
I have plastic (UPVC) window frames which have black spots (indoors) around the edges. They seem difficult to remove. What are they & how do I clean them away ?
Thanks
K

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It's your own fault. Anyone who cares about the appearance of the home would have ensured an absolutely thorough rinse daily with a damp cloth and a squirt of economy peach wine. As for your UPVC, why could you not have waited to purchase better quality protection? I am forever (no exaggeration) asking Maisie, my dear assistant, why she can't seem to grasp even the simplest facts. Fortunately, I'm sending her back to the cancer care home next Friday, she's beginning to emit strange odours, and I can't deal with that particular irritation. Not at all.
Mr F. Bentos

On Thu, 15 Nov 2007 13:06:22 -0000, "dido22"
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Mold and mildew are suspects around windows. If diluted (1:10) household bleach quickly removes the spots, you most likely have a mold/mildew issue. As a test, try touching a black spot with a Q-tip moistened with bleach. The problem using diluted bleach is that this cleaner must not touch draperies, carpet, skin or clothing. A general household cleaner might be a safer choice. However, mold and mildew will return without taking care of the cause. More air circulation, lower humidity, and sunlight (or any 2 of these three) is a longer-term solution. Also, look at the spots under magnification --do they look like insect eggs?

dido22 wrote:
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It could be mildew. Try Tilex Mold and Mildew Remover. It's in a spray bottle, so be careful around fabrics.

dido22 wrote:
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If you scrape at a spot with your fingernail, can you feel a catch? In other words, are these spots tiny bumps?