On the last run there was noticeable streams of smoke. Especially when the system was still cold. Test burn 2 also showed signs of smoke where there was no tape. This tape is not meant for wood stoves, but the temp. on the pipe is no where as hot as the temp out of a conventional wood stove. Yep, the pipe will be embedded in cob. All the more reason to tape it -I figure. The cob can crack and release CO2, so I feel like this step should be taken. It's a small amount of effort for healthy insurance.