I will here show by a series of photos, step by step, how I removed a heavily corroded pin from an old British stoneware Varley insulator. When I got the insulator, the pin was cut flush with the bottom of the insulator, meaning it could not be gripped in a wise. Furthermore, due to corrosion, the pin was heavily stuck in the insulator.

The very first step was to wrap and protect the insulator and its surface with strong silicone pressure sensitive tape. Here you see the wrapped insulator. When de-pinning insulators, never ever forget to also protect the top. Otherwise it will be scratched when you press the insulator to the floor during the work! Now it's ready to be clamped in a wise. To do that, I used a hole saw with a diametre approx the same as the outer diametre of the Varley. I then drilled a hole with it in a straight piece of wood. I then sawed this piece of wood apart, creating two halves in which the Varley could be clamped inbetween. I don't have photo but I hope you understand how I did it. The Varley is very good for this kind of work since its sides are parallell and thus easy to grip in a wise.