mortar powdering out.
The fireplace is more than 25 years old and this is the first winter that the mortar between the bricks is powdering. We are in a damp,cool climate, leave the house during the winters 4 months but maintain the electric heat at 10 degrees. The fireplace is in use for about 3-4 months during the year. If anyone has had this problem and solved it,I would appreciate a reply.