It used to be made by gudebrod, now it is made by woodstock. Buy Western Filament Lead Core. It is made with 99.9% pure lead, it is softer so your lead does not poke through the outer core and the colors don't fade.
Those were the biggest problem I had with the Cortland, but they have changed things and nice colors, love it but pricey, in a pinch it's my favorite now.