Front springs: why are they wrapped with rubber ?

[wkuehnis]

Hi,
I am checking my first Model-A (Fordor, 1931).
The front and rear springs looks very strange. They are totally wrapped with tape and covered with a rubber material.
Yesterday I removed my front spring. Next week I will totally disassemble it. (I am out of town over the weekend)
I hope, you are able to see the photos.
It also looks, like there are 12 leafs instead of 10 and between the leafs, it seems, there are thin metal stripes.

Does anybody know this ?

Thanks for help
Willi