I am in possession of a large ultraviolet torch (flashlight for the rebel colonists over there). This is not entirely accidental. I am also in possession of eight small pots of fluorescent paint that are white until they are illuminated by ultraviolet… I plan to leave an invisible legacy in this rented house.
Anyway. I found an interesting side effect. Here is the top of the cooker with the glass lid up….
Looks pretty clean, right? The big cooking ring on the right side (the hotplate is far-right, so we avoid using it in case Hitler appears) has never been used. It’s for cauldrons or something, I don’t know. Anyway, the rest of it gets cleaned after use but that one gets ignored. Is that a good thing? No, as it turns out..
Here’s what you see when you dim the lights and shine UV on it –
That fluorescent green stuff is bad filthy stuff. It’s invisible to the naked eye but UV shows it in all its gory glory. Okay, this ring hasn’t been used and if it was it would probably burn off most of the unpleasantness but even so. I don’t want the unpleasantness there to begin with.
The torch I used for this demo is a monster but this trick works just as well with a tiny pocket version. Unlike infrared you don’t need to look through a camera to see the effect. You just need low lighting, the crap glows green so you can find it and get rid of it.
I actually bought the torch for photo effects for book covers, but this side effect has proved very useful. It’s been a warm damp summer and mould loves that, so getting dirt it could grow on out of your house is a very good idea. But you don’t need that massive thing. Anything, even a tiny pocket one, will work.
I wish I’d known about this when I was a janitor. Local Shop would have been sparkling clean. And I could have embarrassed the auditors who always gave it a pass.