Moisture problems


After a couple of weeks of sitting in our new office, we’ve noticed the humidity in here is constantly quite high, when we first moved in it was a whopping 78%. It’s worth noting the ideal humidity in a home is around 50% (our old office was around 30%). Since then we’ve been airing out the room daily and have a couple of dehumidifiers, and can get it to around 55% during the day, at night however I does creep back up to ~65%).
It’s also well known in the 3d printing world that moisture and filament don’t mix well. Nylon filament in particular is very susceptible to moisture, whereas PLA is less so, and ABS even less, but the problem is still there, these plastics are hygroscopic and given time they will absorb some moisture from the air.

Even with this knowledge, I’ve still been a bit careless with the filament and have not properly stored it after each day (our silver filament has been sat on its spool for a couple of weeks now), and so I wasn’t surprised when I started to see tiny plastic bubbles bursting from the nozzle occasionally whilst extruding (remember we are heating our nozzle to twice the boiling point of water). You can also visibly see the reduced quality in the print:

Left is filament fresh out of it's vacuum pack, Right is after nearly 1 month of being left out on the spool.

Left is filament fresh out of it’s vacuum pack, Right is after nearly 1 month of being left out on the spool.

One way of removing any moisture from the filament is to dry it in an oven on very low heat, ¬†around 70 degrees, for a few hours. I don’t like this idea for a couple of reasons:

  1. The glass transition temp of PLA is typically 60 degrees, then it starts to soften. Doing a spool like this could cause it to start sticking to itself and deforming.
  2. I’m pretty sure my oven doesn’t go this low in temperature, and if it did I wouldn’t trust it. I would need one of those fancy digital ovens to be sure.

In the mean time I’ve placed¬†it into sealed bags with some silica gel. I have:

  • ordered a sealed blue tub to store any filament we aren’t currently printing with, but is out of its packaging
  • purchased some self indicating silica gel (changes colour from orange to dark green when saturated with moisture)

Regarding the problem with filament being left out on the spool, I’ve used a design from thingiverse and have made a small enclosure for our filament:

For the axle I made a simple hollow cylinder in blender.

Making... For the axle I made a simple hollow cylinder in blender.

There’s a bag of silica gel in there to remove any ambient moisture and a proper feeder hole is currently being worked on that won’t cause any friction on the filament as it’s being pulled up.

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