Western painting critic Robert Coates. Abstract expressionism, Action painting, and Color Field painting are synonymous with the New York School. Technically Surrealism was an important predecessor for Abstract expressionism with its emphasis on spontaneous, automatic or subconscious creation. Jackson Pollock's dripping paint onto a canvas laid on the floor is a technique that has its roots in the work of André Masson. Another important ear<nowiki>ly m</nowiki>anifestation of what came to be abstract expressionism is the work of American Northwest artist Mark Tobey, especially his "white writing" canvases, which, though generally not large in scale, anticipate the "all over" look of Pollock's drip
Drip chamber this instance the rate of flow is usually controlled by a clamp on the infusion tubing; this affects the resistance to flow. However, other sources of resistance (such as whether the vein is kinked or compressed by the patient's position) cannot be so directly controlled and a change in position may change the rate of flow leading to inadvertently rapid or slow infusion. Where this might be problematic an infusion pump can be used which gives a more accurate measurement of flow rate. Drip chambers can be classified into macro-drip(about 10 to 20 gtts/ml) and micro-drip (about 60 gtts/ml) based