03/11/2026
Those black streaks between your window panes? Scrubbing won't shift them - and that's not dirt. It's your double glazing seal breaking down, so no amount of elbow grease will clean it away. If the mark stays put after a wipe, it needs an honest look rather than another go with the cloth. We'll tell you straight whether it's cleanable glass or a failed seal. Sparkling clean glass, every time - give JTPM a call.