LCR (Liquid Creosote Remover) 5/8 Mesh and they are great when

and they are great when they work

And of course

The damper can be shut to seal the chimney

You could use a vacuum to clean them but a less time consuming method is to use the smoke shelf scraper to pull the ash down and shovel it into a container

Huge heat loss occurs when a chimney damper doesn't seal properly or is missing or broken

LCR (Liquid Creosote Remover) 5/8 Mesh and they are great whenLCR is a liquid advanced solution specially formulated to remove third degree (stage) glazed creosote from chimney flues without the need to add water thus reducing exposure to toxic dust It penetrates, dissolves, and absorbs the creosote buildup, causing it to lose adhesion and detach from the flue surface as it dries making it easily removed during a standard chimney cleaning. For use on Stainless Steel, Masonry or Ceramic chimneys.