If I put a pareve immersion blender to blend pareve pesto in a container that I have used in the past for dairy, will the immersion blender also become dairy?
The immersion blender will not become dairy. This is because the container did not come in contact with the blade of the immersion blender. Even if it would have in retrospect it wouldn’t make the blender dairy. Nevertheless it is better to do the blending in a pareve container.