An improved thermally-responsive record material useful for bar coding is disclosed comprising a support having provided thereon in substantially contiguous relationship: a substantially colorless dye precursor comprising 2-anilino-3-methyl-6-dibutylaminofluoran; a sensitizer selected from the group consisting of 1,2-diphenoxyethane and 1,2-(4-methylphenoxy)ethane; an acidic developer material comprising bis-(3-allyl-4-hydroxyphenyl)sulfone which upon being heated reacts with said dye precursor to develop color; and a binder material. The improved thermally-responsive record material and bar code of the invention has a high print contrast signal; high dimensional stability in terms of low bar width growth degradation; a high percentage of successful decodes; and high contrast of the bar code with the background. The invention overcomes difficulties in past efforts to bring together a confluence of these characteristics in one coating formulation.