The improvement of the crease resistance of cotton and rayon fabrics finished with various kinds of resins and its reduction caused by repeated launderings were investigated in relation to the quantitative change of resins before and after laundering. The results were summarized as follows:
(1) The most favorable improvement of crease resistance was observed on cotton fabrics finished with Less-Formalin (LF) type resins and on viscous or cuprammonium rayon fabrics finished with melamine resins. A Non-Formaline (NF) type resins gave unfavorable results.
(2) Glyoxal types (LF, NF) showed the higher improvement in wet crease recovery than in dry crease recovery, while melamine and urea types gave an opposite result.
(3) Insufficient curing gave unfavorable improvement in all the cases.
(4) The laundering lowered the crease resistance in each case according to the number of launderings. In this case, dry crease recovery showed larger reduction in earlier stage, which probably means that breakages of hydrogen bond in the crystalline region occur earlier than that of cross linkages obtained by the resin finishing.
(5) Change in the amount of resins on the fabrics determined by IR spectrophotometry showed that some reduction of crease recovery is observed even if any resin is unremoved.

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An assumption is made in this paper that fabrics are consisted of two parts. One is a nozzle part such as spaces among yarns in woven or knitted fabrics. Another is a capillary part such as spaces among fibers in yarns. The air permeability of fabrics is considered to be the sum of the two factors.
The results show that the air permeability can simply be expressed by the relation beween the pressure difference of flow meter ΔP_N and that of two faces of fabrics ΔP;
√ΔP_N=A√ΔP+BΔP
where, A√ΔP and BΔP are the air permeability of a nozzle part and a capillary part respectively.
The experimental findings obtained by varying the air permeability by removing yarns and/or by oiling the fabric have revealed that the assumed model well corresponds to the construction of actual fabrics.

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