When you wash the rind a number of things happen. One is you are dissolving the surface of the cheese to some degree (even more so if you have alcohol) and another is you are helping to breed b. linens on the surface.
The enzymes of the cheese as well as enzymes produced by the bacteria on its surface form a sticky paste, which is obviously quite high in proteins as it is very glue-like. You will actually get slime in your wash brine from this too -don't worry about it or throw out the brine, it is just cheese enzymes and not spoilage.
This goo can get pretty heavy at times (like the middle of a humid summer) and this is a good thing, it will naturally fill any tiny fissures and smooth over all imperfections in the cheese. The exception of course are large cracks which are past hope.
Now a recap in simple terms.
We wash our cheese daily -but only the side that will be on top. We wet our brush with the wash brine, and rub it around until we have a nice cream. The first wash or two there is not much, but after a few days it is very thick.
The liquid 'melts' the surface of the cheese to make this cream, which harbors beneficial bacteria growth.
It is important that during the first stage of rind formation, the rind be always wet. If it dries off to the point where it is merely damp, that is when mold will grow. Mold grows on damp, not on wet.
You don't want it too wet. It should not be wet to the point where it is drippy or runny. You want to use each time just enough brine so that it forms a good thick cream, and then rub this cream all around so that it smooths out the surface of the cheese.
Also when you make a washed rind like this, it will smell kind of like dirty feet. That's a good thing. But once you let it dry off, the smell goes away.
After a rind has been thoroughly conditioned like this, mold will not be able to grow on it. I have even tried to introduce blue mold to the surface of such a cheese and it simply cannot grow.