A method, comprising: controlling a nuclear magnetic resonance apparatus to expose a material to an NMR fingerprinting excitation by: controlling the NMR apparatus to apply radio frequency energy to the material in a series of variable sequence blocks, wherein a sequence block has a plurality of sequence block parameters and includes one or more excitation phases, one or more readout phases, and one or more waiting phases, wherein N of said sequence block parameters are varied either non-linearly, randomly, and/or pseudo-randomly during the series of variable sequence blocks, N being an integer greater than one, wherein N itself is varied at least once during the series of variable sequence blocks, wherein the material contains one or more resonant species (R1; R2), wherein the RF energy applied during a sequence block is configured to cause the one or more resonant species (R1; R2) in the material to simultaneously produce individual NMR signals (NMR1; NMR2), and controlling the NMR apparatus to acquire the produced NMR signals and to determine an NMR signal evolution from the acquired NMR signals (NMR1; NMR2), wherein the signal evolution is determined by the series of variable sequence blocks; determining one or more parameters of the material for characterizing a property of the material by comparing the determined NMR signal evolution associated with NMR signals (NMR1; NMR2) acquired from the material in response to the NMR fingerprinting excitation to reference NMR signal evolutions for which said one or more parameters are known. controlling the NMR apparatus to apply radio frequency energy to the material in a series of variable sequence blocks, wherein a sequence block has a plurality of sequence block parameters and includes one or more excitation phases, one or more readout phases, and one or more waiting phases, wherein N of said sequence block parameters are varied either non-linearly, randomly, and/or pseudo-randomly during the series of variable sequence blocks, N being an integer greater than one, wherein N itself is varied at least once during the series of variable sequence blocks, wherein the material contains one or more resonant species (R1; R2), wherein the RF energy applied during a sequence block is configured to cause the one or more resonant species (R1; R2) in the material to simultaneously produce individual NMR signals (NMR1; NMR2), and wherein N itself is varied at least once during the series of variable sequence blocks, wherein the material contains one or more resonant species (R1; R2), wherein the RF energy applied during a sequence block is configured to cause the one or more resonant species (R1; R2) in the material to simultaneously produce individual NMR signals (NMR1; NMR2), and controlling the NMR apparatus to acquire the produced NMR signals and to determine an NMR signal evolution from the acquired NMR signals (NMR1; NMR2), wherein the signal evolution is determined by the series of variable sequence blocks; determining one or more parameters of the material for characterizing a property of the material by comparing the determined NMR signal evolution associated with NMR signals (NMR1; NMR2) acquired from the material in response to the NMR fingerprinting excitation to reference NMR signal evolutions for which said one or more parameters are known.