Traditional yerba mate brewing method: if the straw was inserted into dry yerba, the mate must first be filled once with cool water as above, then be allowed to absorb it completely (which generally takes no more than two or three minutes). Treating the yerba with cool water before the addition of hot water is essential, as it protects the herb from being scalded and from the chemical breakdown of some of its desirable nutrients. Hot water may then be added by carefully pouring it, as with the cool water before, into the cavity opposite the yerba, until it reaches almost to the top of the gourd when the yerba is fully saturated. Care should be taken to maintain the dryness of the swollen top of the yerba beside the edge of the gourd’s opening.
Once the hot water has been added, the mate is ready for drinking, and it may be refilled many times before becoming washed out (lavado) and losing its flavor. When this occurs, the mound of yerba can be pushed from one side of the gourd to the other, allowing water to be added along its opposite side; this revives the mate for additional re-fillings and is called “reformar o mate”.