A method of forming an abradable coating is disclosed. The method comprises (i) forming a plasma; (ii) introducing a coating material, in the form of a powder having particles in the range between 1 and 50 μm, carried by a delivery gas into the plasma, the plasma having a sufficiently high specific enthalpy for at least partially melting some of the powder and vaporizing at least 5% by weight of the powder, so as to form a vapor phase cloud of vapor and particles; (iii) forming a plasma beam by maintaining a process pressure between 50 and 2000 Pa; (iv) defocussing the plasma beam by maintaining a process pressure between 50 and 2000 Pa; and (v) forming from the vapor phase cloud onto a substrate surface an abradable coating, being part of an insulating layer system the abradable coating comprising columnar structures. Advantageously, the columnar structured abradable coating (40,41) has an erosion resistance smaller than 30 s/mils, preferably in the range of 5 to 27 s/mils, more preferably in the range 10 - 25 s/mils, still more preferably in the range 15 - 20 s/mils.