That cheap plastic scraper saved me 20 minutes on a tar-glazed flue in Dayton

Had a job over in Dayton last Tuesday where the flue was caked with so much creosote glaze that my usual wire brush just slid right over it and did nothing. I almost went back to the truck for the rotary setup, but I grabbed a stiff plastic scraper I keep for the firebox instead and started working it in short pulls at a low angle. The plastic did not gouge the clay liner like the metal scraper would have, and it broke up the glaze in chunks so the brush could actually grab the rest. Took me about 20 minutes to clear a section that would have eaten up an hour with the rotary head. Has anyone else had luck with plastic scrapers on glaze, or am I late to this one?