Fizik saddle slipping backwards

After messing about with bike fit a while ago I have two seatposts and a few saddles. One of them is a Fizik Terra Argo x3, which has Kium (whatever that is) metal rails. This one is hard to keep in place . The other saddes are fine on both seatposts, but with the Fizik the clamp has to be super tight. The seatpost it’s on at the moment is a two bolt job and it feels like I’m already tightening the bolts a bit too much. There’s nothing special about the size and shape of the saddle rails as far as I know.

Any tips?

Are the rails thinner than standard?

That said, I’ve had Fizik saddles with those rails, and they seemed normal, maybe some carbon grip might help

According to the Fizik website the rails are 7×7, so nothing crazy. Maybe Kium is that little bit more slippery!

I think I do have some carbon paste somewhere so if I can find it I’ll give it a go.

Didn’t need the carbon paste in the end. Turns out Controltech reckon max torque for the clamp bolts is a surprising (to me) 10-12Nm, and I reckon I’d been doing them a good bit lower than that. Greased the bolts too and all good since then.