Jackets for Katsu stones are manufactured of furniture fabric of high mechanical stability. This up-to-date material is much more resistant to dirt than most of organic materials.
But even if your Katsu stone got dirty, you can easily clean it with wet cloth, lint roller or cleaning brush. In case of more serious smear (for instance if your children played with paint) you may use soap or stain remover.
The jacket is removable and also washable. Prior to washing you would have to release it from the contents. But we highly recommend you to avoid doing it as it demands some professional skills to refill the cushion. To take off the inner jacket you would need to unzip the stone and take out some part of the holofiber, this is why the inner jacket is left unsewn.
The jacket recommended washing temperature is not above 40С°.
In order to prevent the stone from unzipping by children, you may remove the zip pendant and use a simple paper clip instead, if you would need to take the jacket off.