You know that black gunk that builds up in the tracks of a sliding window? I ignored mine for a full year because I thought it needed some special tool. It doesn’t.

An old toothbrush and a splash of white vinegar took care of it in one pass.

The method

1. Sprinkle a thin layer of baking soda along the track.
2. Spray or drizzle white vinegar over it. It’ll fizz, which is doing the work for you.
3. Let it sit five minutes, then scrub with an old toothbrush. The bristles get into the corners a sponge can’t reach.
4. Wipe the sludge out with a damp cloth, then run a dry one through to soak up the rest.

If the track is really caked

• Wrap the toothbrush in a thin rag first to scoop out the wet grime before you go in with the brush.
• A butter knife under a paper towel scrapes out the deep corners without scratching the frame.

My windows slide open with one hand now, which sounds like a small thing until you remember what they felt like before. Sometimes the cheapest fix really is the one already in your cupboard.