In this study, the authors investigated penetration patterns of monomeric and polymeric 1,6-hexamethylene diisocyanate (HDI), experimental and as part of common products, in excised full thickness human skin at 5, 10, 30, or 60 min after exposure. It was observed that both monomeric and polymeric HDI were readily absorbed into the skin and that the clear coat compounds affects the penetration rate of the individual isocyanates. The short-term absorption rates for HDI monomer, biuret, and isocyanurate were determined and used to estimate the exposure time required to reach a body burden equal to the American Conference of Governmental Industrial Hygienists (ACGIH) inhalation threshold limit value (TLV) or Oregon State occupational exposure limit (OEL). Oregon is the only government entity in the United States to promulgate a short-term exposure limit (STEL) for HDI-based polyisocyanates biuret and isocyanurate. Based on these absorption rates for a slow-drying clear coat after 10 min (1.33 gcm-2 h-1) or 60 min (0.219 g cm-2 h-1), the authors calculated that 6.5 and 40 min dermal exposure, respectively, is required to achieve a dose of HDI equivalent to the ACGIH TLV. For biuret, the time to achieve a dose equivalent to the Oregon OEL for slow-drying clear coat was much shorter (<31 min) than that for fast-drying clear coat (618 min). Iso-cyanurate had the shortest skin absorption times regardless of clear coat formulation (14 s-1.7 min). These results indicate that the dose received through dermal exposure to HDI-containing clear coats has a significant potential to exceed the dose equivalent to that received through inhalation exposure at established regulatory limits. The authors concluded that based on the results from the study, a critical need exists to monitor dermal exposure quantity in exposed workers, to use proper protective equipment to reduce dermal exposure, and to re-evaluate regulatory exposure limits for isocyanates.