Time to Read: 4 minutes
Quick Overview
That dark stain inside your gourd is almost always normal, the natural result of curing and use, not mold. Real mold shows up as fuzzy white or black spots. Here is how to tell the difference, clean it safely if you do find mold, and prevent it in the first place.
One of the most common questions we get is whether a gourd has mold inside. It can be a little frightening to see something that might be mold in your mate gourd, so let us go over how to spot real mold versus the normal curing of a gourd. If you have not already, our guide on taking care of your yerba mate kit is a good companion read.
What is NOT mold? (the normal curing stain)
The first time you use a natural gourd, a dark green stain appears inside. This is completely normal. As you keep using it, the stain spreads and darkens, and eventually the inside can look almost entirely black. That is the gourd curing, not mold.
What does mold in a gourd look like?
Telling the two apart can be tricky, but the giveaway is texture. A sure sign of mold is fuzzy white or black spots. That fuzz is called hypha. A flat, smooth, dark stain is just curing; anything fuzzy or raised is mold.
What if there is mold?
You do not need to throw the gourd away, it is usually fine to clean and reuse. That said, do not simply ignore it. Clean it thoroughly before using it again, and if you are immunocompromised or at all unsure, err on the side of caution or replace the gourd.
How do you get mold out of a gourd?
Here is how to clean a gourd if you suspect mold. (No mold is visible in the photos below; they are for demonstration.)
1. Boil water and let it sit an hour or more
The inside of a gourd handles very hot water well, so do not be afraid to pour 100°C / 212°F water in. Be careful not to pour it on the outside, especially if the gourd is wrapped in leather, which it can damage. Use water only, no soap or anything else, since that can affect the flavor later. Boiled water alone is enough to remove mold.
2. Empty the water and scrape it off
Scrape the inside with a spoon or butter knife, then rinse with room-temperature water.
3. Pat dry with a paper towel
Pat it dry, then leave the towel inside for about an hour to soak up any remaining moisture and residue.
4. Dry in direct sunlight
Set it outside or by a sunny window to finish drying, turning it if it is on a rack.
Where does mold come from, and how do you prevent it?
Moisture is the main cause, so the fix is simple: always dry your gourd after every use to keep fungi from taking hold. Mold is uncommon in ceramic, glass, or silicone cups. And if you use your gourd daily, it is less likely to form mold, since there is not enough time, though you should still clean it after each use.
Good to Know
If you are ever unsure whether it is mold, the safest move is to clean and re-cure the gourd before your next mate. This article is for general information and is not medical advice.
Frequently Asked Questions
Is the dark stain in my gourd mold?
Usually not. A dark green-to-black stain is the normal result of curing and use. Mold shows up as fuzzy white or black spots.
Is mold in a mate gourd dangerous?
Do not ignore it, but it is usually manageable: scrape it off, clean the gourd with boiling water, and re-cure it. If you are immunocompromised or unsure, be cautious or replace it.
How do I clean mold from a gourd?
Fill it with boiling water and let it sit, scrape off the mold, rinse, pat dry, then dry it fully in the sun. Use only water, never soap.
How do I prevent mold in my gourd?
Empty and dry it fully after every use, and store it somewhere dry. Frequent use also leaves less time for mold to form.
Keep your gourd healthy
A quick clean and a good dry after each use will keep your gourd in great shape. For the full routine, see taking care of your yerba mate kit, or browse our gourds.
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