The retired sweep on Delancey St stopped me mid job to ask why I was still brushing cold
He peeked up my flue at a job in early March, tapped the creosote and said "son, that glaze means your brush is skating over it, warm the flue slow before you scrub" and sure enough a 10 minute warmup pass got more off in one go than my whole hour of cold brushing, so now I'm wondering how many of you pre warm on heavy glaze jobs or just go straight at it.