Yerba mate

[Hassouni]

So I have a mate gourd, and no matter how well I try to dry it, I get black mold spots in it that eventually have to be scraped off. When i got it I did the initial soak-'n-scrape, but perhaps I didn't scrape enough? Do the walls of the gourd have to be really thin to prevent mold?

[Panaderia Canadiense]

Do you wash your mate gourd after using it, or do you leave mate residue in it? I ask because the mate itself, if you haven't brewed it too hot, contains a couple of mold-inhibitor chemicals - this is why Uruguayans will always tell you (in the most strident of tones, yet) that you should NEVER wash your gourd, just rinse it lightly after drinking and then use either strong sunlight or your hairdryer to dry it out.

To answer your other question, if you prepared your own gourd: it has nothing to do with the relative thickness/thinness of the calabash - if it's going moldy, it was improperly scraped or dried to begin with. I see the black mold spots quite often on calabashes that were harvested before they were really ripe, and then scraped and not dried out entirely.

[Hassouni]

I do rinse it out, but I don't wash it with soap or anything.

I'm guessing the mold is bad for me, right?

[Panaderia Canadiense]

It's not that great for you, no. Since you've already got the mold problem, I'd suggest giving your gourd an overnight soak with some 10% hydrogen peroxide (food grade if you can get it) to kill off any spores and deaden the mycellium of the mold. Then dump it out and rinse it with boiling water.

That will take care of the current mold problem, and if it recurs you can always repeat the H₂O₂ tretment.