For the purpose mentioned, probably for plasticising, there are various soft resins but alkyd resins of the medium oil-length type are considered the best. As far as the solvent used with them is concerned. xylene should be more advantageous than white spirit because of better matching of the solubility parameter. However one can not exclude the possibility that the resultant differences in properties will be insignificant compared to those due to the fatty acids in the alkyd resin. Frequently, only saturated fatty acids are used in the interests of increased plasticiser effect.
For special requirements, e.g., high mechanical strength and chemical resistance soon after film application, one should also use unsaturated types. Oxidative cross-linking, which positive consequences, is then possible. Curing tests over a period of up to two weeks can indicate the most appropriate composition of the nitrocellulose lacquer.