Not even sure if I have the correct forum for this issue (please advise!)
I had a house fire in November '17. The repairs were carried out by (in my view) a shambolic crew of builders...don't get me started! I now have two small patches of what I have been told might be efflorescence (see pictures). The 'heart-shaped' one is in the kitchen (where the fire started, so gutted and flooded with water) - you can see that I 'brushed away' the powdery paint a couple of months ago, but it is again powdery around the edges. The 'circular' one is in the hallway (re-plastered after asbestos was found). The shapes themselves are curious? Can anyone enlighten me as to whether it is, indeed, efflorescence and, if so, the possible cause and the best remedy?