3D printing filaments used in the FDM / FFF technology are thermoplastics that are more or less susceptible to moisture, known as hygroscopicity. Special materials, such as nylon or supporting, water-soluble PVA and BVOH are primarily exposed to it, however, this problem can also manifest itself in the popular in home use PLA or ABS. Polymers – the plastics we print from, are made of chains of molecules connected to each other. Moisture causes water molecules to degrade and destroy these chains, resulting in a host of problems during the 3D printing process.
The wet filament manifests itself in a series of characteristic symptoms. During printing, we can hear as if the filament coming out of the printhead “pop” or “crack” – this is the effect of evaporation of water molecules from its inside. The consequence of this is the loss of material from which the workpiece layer is built – this can cause a visible gap on the workpiece surface and much weaker interlayer bonding.
The print from wet filament is ugly, “leaky” and flaccid – with thin-walled geometries it can be easily crushed in hand.
The reasons why filaments get wet are prosaic – we just keep them in wet rooms. Plastics dedicated to thermal processing – that is, melting them in the printhead of a 3D printer require conditions that are not necessarily beneficial to humans. In short, they should be stored in a dry and relatively warm environment, where temperature and humidity are maintained at the same level. This is one of the nuances of working with 3D printers at home – as we always emphasize, 3D printing even in the most amateur edition is, as a rule, still the same technological process that takes place in industrial plants. Simply using a 3D printer at home we have to accept a number of qualitative compromises.
The main thing is not to overdo it with temperature. Although generally available filaments become semi-liquid at temperatures of 180-250°C, they become plasticized at temperatures of 60-120°C. If we overheat a PLA spool by putting it in an oven preheated to 100°C, individual turns of the filament will deform, losing the diameter set by the manufacturer and stick together.
Temperature range for selected filaments:
Filaments should spend 1-4 hours in the oven. The longer they dry, the better, however, experience suggests that this type of action is usually carried out affective, when we discovered the problem and the last thing we care about is wait a few hours for the material to dry…
Before you put filaments in the oven, make sure that its interior is clean (the remains of vegetable or animal fats in the filament will be as destructive as moisture) – it is worth placing them on aluminum foil. First, we warm up the oven to the set temperature and only then put the material inside – we will avoid that the oven temperature has risen by several degrees during heating.
If we do not have an oven or for various reasons do not want / cannot use it, we can use a food dryer (for fruit, vegetables or mushrooms), or in winter (early spring / late autumn) put the spool on the radiator, making sure that its the temperature is not harmful to the filament (this applies in particular to PLA). They are not particularly efficient methods, but in critical situations they are better than nothing.