An improved thermal ink jet printhead and method of fabrication thereof is disclosed of the type formed by the mating and bonding of first and second substrates. The first substrate is silicon with {100} crystal plane surfaces and has anisotropically etched in one surface thereof a linear series of separate through recesses and a plurality of parallel, elongated ink channels grooves. The second substrate has a plurality of heating elements and addressing electrodes patterned on one surface thereof. The through recesses serve as a segmented ink reservoir with each segment having an ink inlet, and the elongated ink channel grooves having one end adjacent the segmented reservoir and the opposite end open to serve as ink droplet emitting nozzles. Each segment of the segmented reservoir is isolated from each other by dividing walls. The dividing walls strengthen the printhead, and the separate through recesses reduce the effects of angular misalignment between mask and first substrate crystal planes. In the preferred embodiment, a thick film insulative layer is sandwiched between the first and second substrates and patterned to form recesses therein to provide the means for placing the segmented reservoir into communication with the ink channel grooves. To produce a multicolor printing printhead, the thick film layer is patterned to form a linear series of recesses, each substantially equal in length to an associated one of the reservoir segments, so that each reservoir segment may have a different colored ink supplied thereto that cannot mix with the ink of the other reservoir segments.