I would say it would depend on the quality of the sporran, there have been in the last few years a glut of sub-standard off-shore products flooding the market, if you were to immerse one of these in water they would no doubt fall apart. Therefore I think you would be much further ahead getting a higher quality sporran, for example my Freelander never needed to be "softened" up nor did either one of my Ferguson Britt sporrans, just my two cents.