The tray has been loaded (remember the 3minute set time). Let the person place it in their mouth. They'll need to sit still until it sets up. You'll know when the alginate is set, as it will feel like a solid in the bowl that you can pull away from the sides in one piece. Carefully and slowly remove the alginate filled tray from the mouth. It might feel stuck, but that's just from the suction. It will eventually come out easily.
