Fourier transform infra–red photoacoustic spectroscopy can be used to obtain high–quality infra–red spectra of textile samples with the minimum of sample preparation. For a wool/polyester blend, the spectrum of the polyester was obtained by subtracting the spectrum of wool from that of the mixture. The resulting spectrum closely resembles that of the polyester. For a wool/nylon blend, the spectrum of the mixture obtained by adding the spectrum of wool to that of nylon was shown to be very similar to that of the actual wool/nylon blend. By quantifying the addition and subtraction processes it should be possible to analyse such binary mixtures quantitatively. A three–component blend of wool, nylon and viscose rayon was also examined and the spectral subtraction process was found to be of value in identifying the components.