The interior of a relatively airtight exhibition case will provide some level of protection against
fluctuating RH conditions outside the case. However, through gradual air leakage, the RH inside
the case will slowly increase or decrease, depending on the condition of the outside RH. The rate
of interior RH change depends on the amount of leakage. If the rate of air leakage is one air
exchange per day, the RH within the case will equal the RH of the surrounding air within one day.
[2] In reality, if there are a lot of hygroscopic materials within the case, the interior RH of a case
with a leakage rate of one air exchange per day will barely change. The reason for this is the
buffering effect of the hygroscopic materials within the case