Beautiful collection,every traditional shaver dreams about finding these great sets...You can halt evaporation by simply dripping candle wax around the cap seal.After using it,just reseal.A zip lock bag helps,but wax sealing is better.
Pick up a roll of 4" parafilm M off ebay for a few bucks. It's plasticized wax film with a paper backing so it doesn't fuse to itself. With a little stretching and pressing it forms a moisture-tight seal against smooth surfaces and itself. It's used in laboratories to seal containers to keep humidity in or out and also by horticulturists to bind freshly grafted trees so they don't dry out. Much easier and cleaner than dripping candle wax everywhere.