The Mate Blog

How to Remove Green Stains from Your Mate Gourd: Expert Tips

Alexis Alexis · Fondateur d'YVY Maté Mis à jour le 4 min de lecture
mold on a mate gourd, green spots

L'essentiel

  • Brown spots are tannin deposits: harmless, they form the gourd's patina
  • White or fuzzy spots signal mold: act without delay
  • Against mold: lemon juice or white vinegar, water at 90°C, 2 to 4 h of action.
  • If that doesn't work, food-grade baking soda is the best option.
  • Prevention comes down to one habit: complete drying, gourd upside down, after every mate

You may have noticed, with a touch of worry, green stains in your mate gourd. These marks, though quite common, can raise questions and concerns about the quality and safety of your mate experience. But don't worry - you're not alone.

In this article, we'll explore together why these green stains appear and, more importantly, how to recognize mold in your gourd and how to get rid of it.

Understanding stains in mate gourds

There are many myths around stains in mate gourds. One of the most widespread is that any unusually colored or textured mark is a sign of mold or decay. In fact, green or black stains are natural and beneficial, enriching the mate's taste over time.

Green stains in the gourd

If you've spotted green or black stains inside your gourd, you might be worried. Is it mold? Is your gourd still usable? Rest assured: these stains are not only natural, they play an essential role in the mate experience.

To understand where they come from, we need to look at the tannins. These natural compounds in mate leaves are responsible for the gradual coloring of the inside of your gourd. As the mate brews, the tannins soak into the gourd's wall, forming green stains over time that gradually turn black.

Beyond looks, these stains play a crucial role in improving your mate's taste. Much like Japanese stoneware teapots, renowned for absorbing the flavors of teas brewed over time, tannin-seasoned mate gourds help enrich the flavor of every brew. This natural flavor-building process is something to celebrate, not fear.

Another benefit of mate's tannins is protecting the gourd: as they build up, they create a protective layer, reducing the odds of mold. This layer also smooths the interior and lets your gourd dry faster. Nothing but upside!

green stain after mate curing

Green stain after curing

Black stains in the gourd

Natural gourds, made from squashes, are all unique and can react in completely different ways.

Some gourds develop green coloring that later turns black with time. Others go straight to black.

As you'll have gathered, black stains are exactly the same as green ones, as we saw above. They're absolutely not mold, but tannins. No risk to your gourd or your health!

green stain in a mate gourd

Green and black staining from tannins

Identifying mold in your natural gourd

Knowing how to identify mold is essential to keeping your gourd in good shape. Unlike natural stains, mold appears as white marks or filaments, often fuzzy or cottony to the touch. This kind of contamination can occur if the gourd isn't dried properly after curing and in its first days of life, or if it's stored in damp conditions.

Telling natural stains from mold is crucial. Natural tannin stains are usually green or black and blend evenly into the gourd's inner surface. Mold, on the other hand, often appears in distinct patches or clusters and can come with an unpleasant smell.

Prevention is the best strategy. That means drying your gourd well after every use and storing it somewhere dry and well ventilated. It's also recommended to empty and rinse the gourd after every use, removing mate residue and preventing mold growth.

mold in a mate gourd

Mold in a mate gourd

Removing mold from your mate gourd

1. Spot it fast: the key to removing mold effectively is detecting it early. The sooner it's identified, the easier it is to remove.

2. Partial cleaning: if the mold hasn't spread across the whole interior, remove it by gently scraping the affected areas with a spoon. Then rinse the gourd with hot water (90°C).

3. Pre-treatment: before curing, it's strongly recommended to apply a mix of lemon, white vinegar and hot water (90°C). Let the solution work for 2 to 4 hours.

4. Full curing for widespread mold: if mold has taken over the entire inner surface, a complete curing will be needed.

TIP: if that solution doesn't work, a preparation of hot water and food-grade baking soda will solve the problem.

Care and prevention for natural gourds

Keeping a mate gourd in good shape takes fairly attentive care in the gourd's first days of life. That means cleaning after every use to remove mate residue and avoid moisture build-up, which can encourage mold. Use lukewarm water to clean the inside of the gourd, then let it air-dry completely.

Drying is a crucial step in caring for your gourd. After cleaning, turn the gourd over and let it drain so no water sits at the bottom, then let it dry in a well-ventilated spot in its normal position. Avoid damp environments, and don't leave it upside down after cleaning - that can create the perfect conditions for mold.

To extend your gourd's life, avoid strong detergents or soaps, which could alter the mate's taste or damage the gourd. Beyond that, our gourds are made from the finest materials and built to last - in fact we guarantee them for at least 5 years!

For more care tips for your gourd and bombilla, we have an article on the subject!

mate gourd tannins and stains

The tannins' effects beginning on a natural gourd

Questions fréquentes

Ma calebasse a des taches brunes, est-ce grave ?
Non — ces taches brunes sont des dépôts de tanins laissés par la yerba au fil des infusions. Elles sont inoffensives et constituent même la patine recherchée par les materos : c'est le signe d'une calebasse qui vit. Seules les taches blanchâtres ou duveteuses doivent alerter.
Comment enlever la moisissure d'une calebasse ?
Remplissez la calebasse d'eau très chaude, autour de 90 °C, additionnée de jus de citron ou de vinaigre blanc, et laissez agir 2 à 4 heures. Grattez ensuite délicatement, rincez abondamment et laissez sécher totalement à l'air libre avant de réutiliser. Si cette solution ne fonctionne pas, une préparation à base d’eau chaude et de bicarbonate de soude alimentaire permettra de résoudre le problème.
Comment éviter que ma calebasse moisisse ?
En la séchant complètement après chaque usage : videz la yerba, rincez, puis laissez-la ouverte jusqu'au séchage total. La moisissure ne s'installe que dans l'humidité stagnante — une calebasse qui sèche bien ne moisit pas.

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