I have read different ways of parging and wonder if the cement and sand mixture can be tinted to match the siding on our home. Also, is this coating going to be affected by Michigan's cold and damp weather. Living on a lake gives us a lot of wind driven rain. The block chimney of old and not smooth as it was originally built.
I would recommend buying colored mortar by the bag and just adding sand and water. If you have more than one batch to mix, it's the most accurate way to keep the color uniform. As for it lasting, it shouldn't be a problem as long as the chimney is flashed & capped well, and isn't currently taking water on.