I've discovered a hidden damp patch downstairs it was a small drip over months, all has dried out so all I have to do is make good. I've been told if I paint straight over I will still see the patch, can I apply a special undercoat / bonding coat to hide the marks? If so can I buy it in B&Q or a specialist shop? They are solid brick internal walls if that helps and the plaster is all good.
Thanks in advance
Thanks in advance