Thats interesting Kronckew! and would indeed be a pretty big mess in the heat. It seems that there are varying versions of producing this type of leather armor, certainly in different cultures and periods. I believe the 'lorica' forms were boiled in oil and water, then actually molded to the anatomical section to be covered, and hardened on drying ( my lay version of what I have understood so far).
We have had some interesting discussions on the situational impact of armor in weather, such as in extreme heat as you described. It seems that even the 'heat of battle' in extreme exertion and intense combat could have dramatic effect on the combatants in armor, let alone the obvious problems with melting wax! hadn't even thought of that one
In the Spanish Southwest, the conquistadors must have faced disturbing discomfort with the armor worn in the oppressive heat that they faced as they were in summer months in the deserts of Mexico and regions to the north. It seems they soon discovered that leather was more feasible in those climates, though other reasons were surely involved as well.
I believe that the many of the American Indian tribes of Plains and Southwest had already established the use of leather as well as the cotton padded forms of armor even before the Spanish arrived. The Spanish presumably also wore jerkins or doublet type garments made of leather as well as assorted mail and plate armor.
Aiontay......need your help here
Could the Indian tribes have known of a process for hardening leather in the manner of cuir boulli in these pre contact times ?