Mill Finish is the natural appearance of the aluminum as it comes from the rolling mill (Alcoa, Reynolds, Kaiser, or Alcan) or the extrusion mill. It is as is with no external mechanical or chemical finishing. Extruded metal is considered mill finish. All aluminum has an oxide of some varying thickness. Anodizing is a very heavy controlled oxide.
As they are so small of approximately 5-20 micro-metres in diameter, they do not need valves, as there is a distinct flow from the arterioles supplying the capillary with blood, and the venules draining the capillary within the double circulation.
Veins carry blood from the heart to the body. Capillaries are made of very thin walls. The walls have small openings through which leukocytes (white blood cells) and plasma (liquid part of blood) can leak out to form tissue fluid. The lumen is very small (10 micrometers across) so capillaries can fit into tiny spaces.eins carry blood from the heart to the body. Capillaries are made of very thin walls. The walls have small openings through which leukocytes (white blood cells) and plasma (liquid part of blood) can leak out to form tissue fluid. The lumen is very small (10 micrometers across) so capillaries can fit into tiny spaces.