Can I sharpen a serrated knife in the Vulkanus?
Of course: Hold the knife horizontally and turn it with the sharpened side of the cutting edge towards the sharpening insert.
I have a ceramic knife, may I sharpen it in Vulkanus?
No, by no means. These knives are made of a particularly hard and
sensitive brittle material. You would damage both your knife and your
volcano. Take the knife to a professional sharpening service.