Hey Fam,

Let’s clear up a big point of confusion I see all the time.

If a bag is contaminated, it’s done. Mycelium doesn’t “heal” contamination — at best, it walls it off or grows around it. That doesn’t make the problem go away. The only place you can actually cut out contamination is on agar.

Now, not everything you see in a bag is contamination. Sometimes you’ll spot yellow or orange liquid, often called “myco piss.” The real term is metabolites — enzymes the mycelium excretes under stress. This can come from too much moisture, tight grain, or light bacterial pressure. On its own, that doesn’t always mean the bag is finished.

But if you’re seeing green (Trichoderma), black (molds like Aspergillus), or fuzzy gray cobweb growth, the bag is compromised. At that stage, every time it’s moved, spores are spreading — and it just becomes a mess. Blue, on the other hand, is usually bruising, not mold.

The rule is simple:

• Metabolites (yellow liquid) = stress, watch it closely.
• Mold colors (green/black/gray cobweb) = contamination, toss the bag safely and start fresh.

It’s better to lose one bag than contaminate your whole space.

Stay rooted,

Nick