When you open a newly purchased reel of filament, you will undoubtedly see a dessicant packet fall out. The dessicant helps keep the filament dry.

Filament is hydroscopic, meaning “readily taking up and retaining moisture”. When filament absorbs moisture, two bad things happen: its diameter changes (which can affect print quality); and as moist filament passes through the hot end, the water will boil off, causing hissing and popping sounds as it also affects your print quality. So dry filament good, wet filament bad.

So always store your filament (while not using it) in an airtight container with sufficient dessicants to keep it dry. I usually use 3 5-gram packets in a Ziploc bag holding the filament.

However, since dessicants are also hydroscopic, they lose effectiveness over time. So how do you know when the dessicant is no longer good? You don’t!

A solution for this is to purchase rechargeable dessicants. When purchased, the packets are either blue (that change to pink when no longer effective) or orange (that change to yellow). You recharge it by putting it in a low temp oven, or in a microwave on defrost. Instructions are on the package.

I use these “Dry & Dry” packets: Dry&Dry