Ink Vehicle Is too acid: If the ink vehicle contains too much of fatty acid it can destroy the desensitizing film on the non-image areas of the plate. Sometimes a fatty acid like oleic or a compound of it is added, in an attempt to counteract blinding of a plate (loss of ink receptivity in the plate's image area). This should be done with great care so as not to overdo it. Usually about half an ounce to a pound of ink is likely to cause scumming.