I have been enjoying my research into period sealing wax, and recently applied wax I had made to a new apprentice contract. On my way home I stopped to eat, and the contract sat in a hot car for a couple of hours. This, perhaps unsurprisingly, caused the wax to melt and ruin the seals.
This serves as an object lesson on why sometimes we as modern people must make adjustments to how we do things relative to the historical people we are trying to emulate. The climate in Europe in the 16th century was cooler than it is here in the southern US, and they would likely not have left a sealed document in an enclosed metal box in the sun. Perhaps there are instances of seals melting in this way, and I am curious whether wax seals were ever used in hotter climates like North Africa. Shellac based sealing waxes may also be more resistant to this type of heat exposure.
In any case, I feel that it will be safest in the future to fall back to using modern waxes for important things like scrolls that are at risk of this sort of danger. For more ephemeral items like letters I will probably be willing to take my chances on my homemade wax.