A lot of weekend do-it-yourselfers aren't sure when to use putty and when to use caulk. It's simple if you remember this rule: putty is a doughlike compound used to fill in holes (such as from nails) and for surface defects or open spaces. But by definition, caulking is different. It's an old shipbuilding term that means filling the seams between the planks to make a vessel watertight. Today, caulking still means the same. It's used to prevent water damage on long seams such as around windows and doors outside, and around sinks, tubs and showers inside. Other uses for caulk include hiding gaps in woodwork and filling long narrow cracks in ceilings and walls. So if it's a hole or a scratch use putty to match, but if it's a long, open seam, where water can leak, just lay in a bead of waterproof caulk like silicone. And that's the On The House tip for today.