How to Spot Wet Filament? Crackling and Steam Signs

Even with a brand-new spool, if you hear strange noises during printing, the problem is usually the material, not the machine. Wet filament symptoms are actually quite recognisable; once you’ve noticed them, you’ll never miss them again. Filaments tend to absorb moisture from the air, and that moisture suddenly vaporises inside the molten plastic, sabotaging your print.

Listen Closely: Crackling and Hissing

When damp filament passes through the nozzle, water molecules inside instantly turn to steam at temperatures above 200°C. This creates a series of small pops heard as a crackling or hissing sound. The noise is quite noticeable when printing in a quiet room. It resembles the sound of something frying in oil and repeats at regular intervals.

Visual Signs

Even if not as obvious as the sound, moisture leaves clear traces on the surface. You may occasionally see a thin wisp of steam rising from the tip of the nozzle. On the print itself, watch for:

• Bubble-like roughness on surfaces and a dull, washed-out appearance
• Excessive stringing and broken flow between layers
• Poor layer adhesion and unexpected brittleness
• Irregular, foamy residue accumulating around the nozzle

Especially with moisture-prone materials — PETG, nylon, and TPU — these symptoms appear much faster. Even PLA can develop these issues within weeks in a humid environment.

A Simple Test to Be Sure

If you’re suspicious, print a small test piece and inspect it closely. If there’s surface roughness and crackling sounds, your filament has most likely absorbed moisture. The solution is usually drying the filament at the appropriate temperature; a filament dryer or a low-temperature oven will do the job. It can be surprising how much the print quality improves after drying with the same filament.

At our workshop we check every spool before printing and dry it when necessary before processing, so that moisture-related defects never show up on your part. If you’re considering a professional print for your own project, share the details and get a quick quote.

Once you start chasing crackling and steam, you’ll immediately notice how much your print quality improves. All it takes is keeping your ears and eyes open before you open your next spool.