May I suggest getting a 3M green scouring pad, available in your grocer's cleaning section? It's more rigid vs the pliable cotton. Alternatively, sponge packing material -- it works well too.
One note of caution to MonsterZero: while the look may be artistically pleasing, this affect is commonly overdone. May I suggest you spend some time looking at some actual color photos of AFVs (not in museums) in the field or some construction equipment? Paint just doesn't wear off like that in general in the real world.