Dark marks on silicone sealants are typically mould and can be caused by high moisture levels, poor ventilation, organic residue on the sealant (such as soap, shower gel and shampoo), and high ...

Q: My landlord’s novice repair person caulked around the bathtub — twice. Both times, the caulk pulled away from the wall. Why? And what’s the right way to do it? A: New caulk doesn’t stick well to ...