Damp kitchen floor

[BovrilonToast]

Has anyone used a liquid damp prof membrane with any success?

We have bought a house that has been extended and we thought we had a leak in the kitchen floor.

It looks like what's actually happened is when the old external wall was ripped out there was no damp proofing applied to the area where the wall was. Everywhere else is dry!
So my solution is to paint the concrete with liquid dpm. Can anyone recommend a product?