Getting Your Mirror Defogger Wattage Just Right
Ever step out of a hot shower and realize you’re staring at a wall of white fog? It’s annoying. Basically, the cold glass hits that humid air and creates a mess. To fix it, we use shortwave infrared lamps to warm the glass up just enough that the fog can’t stick. But here’s the trick: you can’t just throw the highest wattage you can find at the problem. It’s all about balance. Picking the right power You’ve got to match the power to the size of the mirror. If you’re dealing with a small powder room mirror—something under 600mm x 800mm—you’re probably looking at 50W to 100W. Go too high here, and you’re asking for trouble. You could actually overheat the mirror backing or, worse, crack the glass. Not a great look. Now, for those big master baths or walk-in showers, you’ll need more muscle—maybe 200W or 300W. But don’t just buy one giant, powerful lamp. Instead, spread that power across a few smaller ones. It keeps things even and stops you from getting those weird “hot spots” where one part of the mirror is clear and the rest is still blurry. The technical side of things We use quartz envelopes for these lamps because they push heat into the glass almost instantly. It’s fast. But there’s a catch. More wattage means more heat at the mounting points. You need to make sure your wiring and adhesives can actually handle that heat. If you try to cram a 300W lamp into a housing meant for 100W, you’re probably going to fry your connection points. Real-world installation When you’re actually putting these in, make sure the lamp is sitting completely flush against the mirror backing. Any little air gap acts like an insulator. It kills your efficiency. If it’s not seated right, you’ll be burning power and still staring at foggy corners. My best advice? Grab an IR thermometer during your first test run. It lets you see exactly where the heat is going so you know it’s spreading evenly across the whole surface.