We recently removed some pictures from our walls to repaint and noticed that there seemed to what looked like mold on the wall area where the picture had been hanging. It this really mold growing and why and what can I do to prevent this in the future?

We talked with Western Technologies and they informed us this is a common occurrence on exterior walls due to a couple of reasons. The first reason is that your home is possibly lacking in insulation and/or poorly insulated and the next reason this would be happening is if your home has masonry walls. Condensation accumulates and collects because the interior of your home remains somewhat cool with the exterior of your home having heat build up during the summer, therefore condensation forms on the exterior walls and there is no air movement behind pictures so that particular area remains moist and warm and you have created a wonderful growing area for mold. Ways to prevent this would be to regularly clean and dust the areas behind pictures, particularly those hung on exterior walls. Mold settles and loves dust so regardless of wall locations, all wall areas behind pictures should be dusted often. It would also be good to apply spacers to the back of any pictures and artwork, this would allow the picture to not hang directly on the wall area, therefore there would be air movement. If you see mold in other areas and or this is a continuous issues, your home could have high humidity which may indicate a water leak somewhere in the home.