Problem, though — ALL wood is treated nowadays, it has been for years — so even wooden barrels would pose a risk, although you’d think that there’d be plastics to get plain UNTREATED lumber.<<<
Could one go to the sawmill and get green lumber, as sawn, then allow to age and make it into boxes, along the line of the old style cedar chests?
Making your own chests would be better than barrels, as they will stack on each other.
Sealing will take some research, but maybe wood ashes mixed with water will work, to make a putty to seal the cracks in them, for insects do not like hardwood ashes.
I find that I use more mustard now, as I do not like the mayo in plastic jars.
Imagine my shock that the kitchen was filled with bellowing black smoke, the Smoke Alarm was SILENT, even though engulfed in smoke.
The reason is because the smoke alarm is constructed to react to CHEMICALS in treated woods, and will NOT react to untreated burning wood.
Really got me angry --- the smoke alarms are barely controllably if within 100 yards of a lit cigarette, but a little old "bonfire" on the range top provoked NO response.