In connection with expanding our house, we needed to extend the chimney. About one meter has been added to the existing chimney. Everything looked great when it was completed in November. Sometime in February, I noticed that the chimney had developed a white coating that can't be scrubbed off. Does anyone have any idea what this might be and why it has occurred? I will be getting a visit from the mason shortly to have a look at this, so I might get an answer from him. However, I'm a bit curious if anyone else has encountered this before.
We had a new chimney crown built last fall. A week after it was finished, the chimney guys came and washed it with a hydrochloric acid solution. This was done to prevent salt efflorescence, and there hasn't been any.