Radiator bleed screw

[gideonr]

Had a nice day out in the car yesterday, but went back into the garage later in the evening to be greeted with a pool of coolant. Turns out that it was coming from the radiator bleed screw. I was only finger tight and the seal/washer seems to have disintigrated.
Can any sort of seal be used on the bleed screw or is there something special I need?

Chimaera 400HC

[gideonr]

Cheers all,

New fibre washer and topping up the cooling system as described in the bible seems to have done the trick.