Early 1950s video tape recorders (VTR) were so expensive, and the quality degradation caused by copying was so great, that a 2-inch Quadruplex videotape was edited by visualizing the recorded track with ferrofluid, cutting it with a razor blade or guillotine cutter, and splicing with video tape. The two pieces of tape to be joined were painted with a solution of extremely fine iron filings suspended in carbon tetrachloride, a toxic and carcinogenic compound. This "developed" the magnetic tracks, making them visible when viewed through a microscope so that they could be aligned in a splicer designed for this task.