No, is no plaster. Is a bi component silicone for moulding. Because my difficults with the english, better a video of this material.
https://www.youtube.com/watch?v=8HyV...FC86FD2A729E87
As you can see here, the moulding silicone does not adhere to objects, just fill in the gaps. To center the mirror without play, it would be better a metal tube, but obviously the silicone is cheaper...
