Just learned creosote can actually harden into a glass-like glaze in hot chimneys

Ngl I was reading through an old NFPA report yesterday and found out that when chimney temps get above 2,000 degrees, normal creosote can turn into this shiny black glaze that's almost impossible to scrape off. Apparently it happens a lot in wood stoves that burn really hot fires with unseasoned wood. The scariest part was reading that this glazed creosote can cause chimney fires that burn way hotter and spread faster than regular buildup. Has anyone else run into this stuff in the field? I'm wondering if chemical treatments actually work on it or if you just have to replace the liner.

2 comments

2 Comments

elliot_harris251mo ago

You ever had to deal with that glaze on a stainless liner? Honestly, I ran into it a few years back on a customer's setup who was burning nothing but green pine. Tried the chemical treatments, the powder stuff you mix with water, and it barely touched the glaze. The only thing that worked was a rotary chain whip on a drill, and even then it took a solid hour per section. If it's really bad and the liner is getting thin, replacement is the safer bet cause that glaze can crack and peel off in chunks that block the flue.

logan_schmidt1mo ago

Actually, have you tried dry ice blasting on that glaze? It's way gentler than chain whips.