Steam Room

Uppers in the steam room

Uppers, closed and steaming (!) in the Loake workshop

This process is not ubiquitous, but some manufacturers store the closed uppers for some days/weeks in a controlled humid atmosphere, as they find that the absorption of moisture helps with “moulding” the upper on to the last. Humidified leather is more likely to stretch where desired and less likely to crack or split. Spending too long in the Turkish bath can cause mould, however, so this process must be monitored closely.