@tyme this is actually a very serious question.
I care for the environment and in my culture I am a custodian of country
So to try to care for the air, I only burn seasoned hardwood that has been cleared from infrastructure projects ie not just logged from forests.
Hardwood burnt correctly, even with the highest quality flue filters should not cause build up in chimney for like 50-100 years.
This is why traditionally we do not clean chimneys/flues in Australia we mostly have hardwood naturally. In USA where they burn a lot of softwood inlcuding pine they need to clean their chimneys because the resin in the pine builds up on inside of chimney,
In the UK in the past they burnt poor quality coal, because the best stuff was used in industry and so low grade coal was cheap, they also needed to clean their chimneys, hence the traditional job of chimney sweeps. Thankfully due to environmental standards people can no longer burn low quality coal in UK
Sorry ridiculously long answer.
TLDR - only burn hardwood
