What mediums did van Eyck use?

Rembrandt used oil paint for his paintings. He is also well known for his numerous etchings. To complete an etching one uses a steel or copper plate, draw the image with a tool known as a dry point and then ink and a press to print the image onto paper.

That is true but it doesn't answer the question of what is Rembrandt's medium. Rembrandt's medium is a cooked oil. Nobody is quite sure exactly how it was prepared but its thought to be a "burnt plate oil", either linseed or walnut. The oil is heated to its flash point (about 400c) at which temperature it thickens. The siccative properies of the oil are changed and painting with oil treated in this way produces similar impasto effects that we see in R's work.