skin treatment

Hello congueros,
as I mentioned in my post about the 5 drums, I just got new super tumba.
I bought the set of drums over a few years and the drums are the same but the bauer skins have changed four times. The two oldest are great skins and of course the quality went down after.
I will probably change all of the skins when I can find my way to the mysterious places far in the Rio suburbs where the good skins are apparently to be found.
In the mean time, those skins I have, seem to be good to begin with but the chemical treatment has made them worse.
The quinto has a very white skin, extremely hard and smooth. It is hard to get a tone by rubbing the finger on it.
One tumba has a similar feel but less so. It definitely sounds inferior to the other identical tumba.
The super tumba has a different problem, it sounds great but the surface has been completely stained by that white glaze. It is hard to describe. The sides of the drum don't have that white stuff. It is as if the treatment had been applied to the skin after it was mounted.
What could I do to make them a bit smoother and get rid of the white stuff?
as I mentioned in my post about the 5 drums, I just got new super tumba.
I bought the set of drums over a few years and the drums are the same but the bauer skins have changed four times. The two oldest are great skins and of course the quality went down after.
I will probably change all of the skins when I can find my way to the mysterious places far in the Rio suburbs where the good skins are apparently to be found.
In the mean time, those skins I have, seem to be good to begin with but the chemical treatment has made them worse.
The quinto has a very white skin, extremely hard and smooth. It is hard to get a tone by rubbing the finger on it.
One tumba has a similar feel but less so. It definitely sounds inferior to the other identical tumba.
The super tumba has a different problem, it sounds great but the surface has been completely stained by that white glaze. It is hard to describe. The sides of the drum don't have that white stuff. It is as if the treatment had been applied to the skin after it was mounted.
What could I do to make them a bit smoother and get rid of the white stuff?