Polymaker PolyDryer Desiccant: Trust, But Verify

The startup ritual for a PolyDryer box’s humidity meter includes:

• Opening a small sealed bag containing …
• The DO NOT EAT desiccant, to be cut open and …
• Poured into the meter box

Which looks like this:

However, the desiccant packets for the most recent pair of boxes (intended to simplify changing the desiccant in the collection feeding the MMU3 atop the Prusa MK4 3D printer) produced this:

The silica gel in the left cup looks OK-ish, maybe a little dark, but the fresh-from-the-bag beads in the right cup are crying out for regeneration after having adsorbed about all the water vapor they can.

If you were using that silica gel in its original DO NOT EAT bag, where you can’t see what it’s telling you, you might wonder why it wasn’t doing such a great job of drying the box + filament. The same could happen with a bag of non-indicating gel, along the lines of what I was using a decade ago.

So I dumped both in the Needs Rgeneration bottle and filled both meters with 25 g of fresh silica gel.