Garage was earlier used as home for one or more large dogs, and there was lots of grime and greasy dirt on the walls and the floor. The epoxy covered floor cleaned up ok after lots of hot water, strong detergent and elbow grease. Still seems ok after a few weeks. The walls, not so much. Drywall (gypsum), and they were painted prior to the dogs moving in. I have scrubbed and cleaned every square inch of the walls and ceiling, as above using hot water, strong detergent and lots of effort. Came out well, and remained "odorless" for many days, after which I then painted all walls and ceiling with a "masonry coating" paint. It is for basements, outhouses etc, and will allow "humidity" to transfer from inside the wall, to the room, where it can evaporate. Standard paint and method for Sweden, and normally totally fine. However, after some weeks, the smell of dog fur has now permeated the fresh paint (2 layers), and the garage smells like a badly kept kennel again. I can smell the odor coming from within the walls themselves. Any recommendations on how to proceed? My only hope is to find an "airtight" paint to keep the odor locked in the drywall. Please note that I am in Sweden, so specific brands and labels may not be available to me. However, indications on "acrylic is better than oil based" etc are very welcome. Many thanks in advance!