Powder compositions hardenable by radiation usable for preparing paints or varnishes, specific amorphous polyesters which are comprised within these powder compositions, the use of the paints or varnishes comprising the powder compositions for coating an article as well as articles coated with the hardened paints or varnishes are disclosed. The powder compositions of the invention are especially suited for coating over metal and heat-sensitive substrates and combine, upon melting at low temperatures and curing by radiation, a series of properties such as good flow and film hardness along with an outstanding solvent resistance.