this invention relates to the coating of textile sheets with polyurethane pastes by the reversal process for producing very soft coating articles with a hand resembling that of napa leather . the particular properties of the coating are obtained by using bonding pastes which contain a mixture which can be cross - linked by the action of heat , consisting of polyurethane hydrazodicarbonamides and melamine - formaldehyde resins and / or urea - formaldehyde resins .