Glaze Creosote and TSR

Looking up from the bottom of a masonry chimney without creosote glaze.

Creosote buildup can, over time, harden into a glass-like, shiny black substance (also known as “glaze”) which cannot be removed through ordinary brush sweeping.  Glaze creosote is extremely tough and difficult to remove.  Any brush or chisel powerful enough to physically chip the surface of the hardened creosote would also damage the inside of the chimney flue.  This creosote must be removed through the use of chemicals.

The smoke chamber in the photo at bottom right is covered in glaze creosote.  Normally, a smoke chamber is not black — it is the red or brown of normal masonry, like the top image.  The dark spot in the center of the bottom image is the chimney flue, which is also clogged with glaze creosote.

Looking up from the bottom of a chimney covered in third stage "glaze" creosote.

TSR chemical creosote remover (made by August West) is more powerful than the creosote removers found in the hardware store and is designed for application by a professional chimney sweep only.  First, the chimney is swept to remove any loose creosote and to prepare the creosote layer for chemical application by roughening the surface with the sweep brush.  Then, TSR is applied with a sprayer by a technician and allowed to sit undisturbed for up to a week while it “eats” the creosote layer.  The technician then returns to neutralize the chemical solution and sweep away the remains of the creosote layer.

TSR often works in one application, but sometimes the accumulation of creosote is so thick that the chemical cannot dissolve the entire creosote layer all at once.  In this case, one or more additional applications might be needed.

While TSR is extremely alkaline and should only be applied by a professional with appropriate safety equipment, during routine application it will not harm your children, pets, or furnishings.  The TSR material safety data sheet is available here.