{HEAD ~ Apparatus} and methods for controlling application of a substance to a substrate involve {TAIL ~ the use} of a functional agent that blocks the substance from or attracts the principal substance to the substrate 
{ HEAD ~ Apparatus } and methods for controlling application of a substance to a substrate involve { TAIL ~ the use } of a functional agent that blocks the substance from or attracts the principal substance to the substrate
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH