Bitumen

Having got the new glass for my fire in place, I was very pleased to get a fire going, after a few days without. All went well for the first half-hour, but then I noticed it was getting difficult to see the flames – the glass was blackening up on the inside. I'm used to cleaning soot off, so the next day I got out the cleaner spray. Nothing had prepared me for what I found on the glass.

It was covered in a bituminous deposit that the spray didn't touch, not even with a hard scrub with paper towel, cleaning cloth or nylon scrubber. It seemed like volcanic rock! In the end I took a Stanley knife to it and managed to cut pieces off, scrape by scrape.

I've been trying to think where it came from. The obvious source was the smokeless fuel, but this was from the end of a bag of Supertherm which had given no trouble before. The only new thing introduced to the fire was some copper grease I used in the holes for the screws holding the glass in. But there was nowhere near enough of that to have created this mess.

Eventually I had cleared about half of the deposit before we really wanted to have the fire going so I left the rest to another day. My chief worry is not the time expended, but that I might be leaving scratches on the glass that will make it more susceptible to breaking.

However, this weekend we are at Fazeley for a BCF get together. Peter of NB Sonflower assures me that (a) the deposit has definitely emerged from the fuel, and (b) it will eventually burn off if I get the fire running hot enough. If he's right, great. But I hope I don't burn out the sitting area doing so!