Skimping on the moisture component is a major sandwich-building no-no. No one likes biting into a dry sando. However, that moisture component means (shocker) wetness - and when water molecules get trapped with no place to go, it can lead to soggy bread. For this reason, ditch the plastic sandwich bags for wrapping and storing your sammies. Whether packing a lunch or storing sandwiches for later enjoyment, plastic sandwich bags and plastic clingfilm both trap moisture inside and cause the bread to become soggy.