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3D Printing Waterproof Parts

Arun Chapman

The number of applications for 3D printers is endless even though they can sometimes be hindered by reality. When printing parts which require holding water, they may often leak. There are still ways to prevent that from happening.

Waterproofing watertight parts

It is possible to waterproof these parts despite the fact that it is not always that easy. In order to achieve the best possible result, one needs to be very careful about the material and the settings. Still, the parts may require some post-processing in order for them to be waterproof. When something is waterproof, it is expected that it is capable of pushing water out. The term water-resistant is also used when something keeps water out up to a limit. The parts that keep water in are watertight. Here, the word “waterproof” is used as an umbrella term for all of these terms.

There are certain stages that need to be followed in order to make something watertight and water-resistant even though not all parts require the same criteria. All in all, it would be wise to not rely on a printed part to protect sensitive material.

How waterproof parts are printed

There are three essential points in order to achieve waterproof parts which are: the material used, your slicer settings, and post-processing. Waterproof parts can be printed in a range of different 3D printing technologies. Many expensive industrial 3D printers have the ability to create highly reliable waterproof parts using metal. The majority of people cannot access these printers. In this case, it would be best to concentrate on the ones which are common, such as FFF printing. 

Materials used

A good deal of FFF filaments consists of thermoplastics. Plastic is a reliable element when it comes to producing waterproof objects such as water bottles. Another advantage of plastic at this point is that water does not damage it. Before starting to print waterproof parts, it is essential to know that there are still different kinds of thermoplastics which have a variety of characteristics.


Several materials used in 3D printing are hygroscopic; they absorb water. PETG, Nylon and PLA are not as good as others while ABS and PP are better than most. However, most of these materials absorb water up to a point. When a part is exposed to water for long, some swelling occurs. Despite the fact that this swelling might be small, there is still deformity on the part and it may even start to break which means that it is no longer waterproof or watertight. This swelling stops after some time. One may think of drying this swollen part, but this may cause more damage to occur.

Slicer settings

The working principle of FFF printers is that they stack the materials layer by layer. However, there is always the possibility of a small gap occurring between every layer. In order to prevent this from happening, there are some settings that should be followed.

Wall line count

Wall line count is self-explanatory in that it is the number of layers there are in the outer wall of the print. Basically, the principle is that the more layers there are the more waterproof it is as there is less possibility for the water to pass through the walls. If, by chance, there is a tiny gap, the other walls will protect it.

Normally, 3 is a good number for wall line. It is important to know that when there are more wall lines, it does not protect the part. A single wall may be sufficient at times, namely when you use vase mode.

Vase mode

Vase mode is also referred to as spiralise outer contour, which is a setting that is capable of printing objects with single wall line. There is one continuous print part, meaning there are no retractions and no Z seam, which is the most important advantage of vase mode. Z seam is the most common areas where a gap occurs. When Z seam is removed, a single-wall part becomes waterproof. Still, the parts that require certain geometry are not suitable for this setting. Vase mode is best suitable for vases, cups, bowls etc.


When two layers are not bonded appropriately, gaps occur. In order to increase layer adhesion, the printing temperature must also be increased. Depending on the material, the highest possible temperature should be set to print at. If the temperature is too hot for the material, it may boil which leads to more gaps.

Flow rate

The most common reason that there are gaps in a part is under-extrusion. Prioritising high dimensional accuracy, structural strength or visual fidelity may cause to under-extrusion even in well-tuned print profiles. Increasing flow rate slightly might be enough for development. Starting with %105 and increasing until you see a reaction might be sufficient.

Post-processing parts to make them waterproof

Apply a waterproof coating

Waterproofing spray, a clear coat, water-resistant paint can cover up the gaps in a printed part, which is the easiest method.

Vapor smoothing

A chemical is used to melt the surface, which smooths the part and removes the layer lines. This method makes the part look more appealing and makes the part more waterproof by filling gaps.

Temperature treatment

There are two ways and two purposes of temperature treatment. It is used to apply heat to the outside of a print which causes the surface to melt in a way to fuse the layers together. This is very similar to vapour smoothing. The other way is to heat soak the part in a period of time, which is called annealing. This causes the layers to bong together more strongly.

What are the applications for waterproof parts?

Scientific research

Scientific research on fluid dynamics and microfluidics are a great area for 3D printed parts.


Plant pots, composting containers, and hydroponics are some of the areas suitable for 3D printing. It is important to use materials that are suitable for the climate.

Plant pots, composting containers, and hydroponics are some of the areas suitable for 3D printing. It is important to use materials that are suitable for the climate.

Water features

3D printed water features can be perfect for a pond or a fish tank.

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