Is a 3D printed vase watertight?

A 3D printed vase has many advantages over a traditional handmade or blow-molded vase. It all starts with an idea or concept for a design. A design that is created using digital CAD / sculpting software, such as Fusion360, Rhinoceros3D or Blender. These software give you the freedom to make a design the way you want it, with few geometric shape constraints, so you can then 3D print it. In order to print an object, you need a material called (3D printer) filament. Nowadays there are many materials on the market for both aesthetic and technical applications, but for vases, you will usually see PLA or PETG for their visual appeal, UV resistance and wide variety of colours.

While making your own 3D printed vase can be mesmerising, they are not necessarily watertight. The nature of layering production brings with it challenges around waterproofing and water tightness.

What is the difference between a waterproof and a watertight object and what are the possibilities to make a 3D printed vase watertight? Although making a 3D printed object watertight is not impossible, many factors play a role. That is why I have attempted to outline some of the options in this blog. Not only for if you have a 3D printer and want to experiment yourself, but also if you are generally interested in these challenges.

Watertight vs waterproof? What is the difference?

Water resistant means that water does not affect 'the material the object is made of', which means that no defects (such as small holes) will appear over time. Watertight means that no water can enter or leave the object.

Since real flowers need water, the 3D printed item must be able to withstand long-term exposure to water and sunlight. This means that the 3D printed vase has to be waterproof and watertight.

A 3D printed vase is built up in layers. Due to the nature of production, small layers of plastic are stacked and melted together to create an item. Although the layers usually fit together neatly, there is still a chance that there are tiny gaps between them that cannot be seen by the naked eye, but are large enough for water to pass through.

There are a number of possibilities, each with its own advantages and disadvantages. I will explain three of them below: print settings adjustments, design adjustments and post-processing.

Print settings adjustments

I usually print a vase with one one thick outer wall. This makes the chance of leaks when pouring water into it, considerable. However, by using multiple outer walls (perimeters) I can reduce this chance significantly. If I print two outer walls instead of one, for example, I increase the density of the wall, which reduces the chance of leaks. However, the print head must cover twice the distance per layer, which means that the printing time is increased exponentially. Also, considerably more material will be used per object. To minimise this, it is possible to adapt an existing vase design or create a new one. For example, by slightly narrowing the shape of the vase, you can significantly reduce the distance the print head has to travel and the amount of material it has to use.

In addition to adding extra outer walls, you can also choose to use a lower layer height to improve the density of the outer wall. In Jakub Kočí's blog on PrusaPrinters he says the following: "To be clear, it seemed that the main source of leakage wasn't from contact between layers but seams and the transitions between solid infill and perimeters.". So it seems that the density of the walls of an object is an important factor in making an object watertight.

He also stated that you can increase the flow rate by 5 to 10%, causing more material to flow through the nozzle, thus increasing the density and closing any holes. Although this could be done, it also has an impact on the appearance of the outer wall of the vase. So that is something to take into account.

Design adjustments

In addition to the print settings, you can also adjust the design. Different shapes and textures each have their own influence on the water resistance and water tightness of the vase. For example, outer walls with steep overhangs are stacked more stepwise, which increases the chance of leaks. Whereas less complex shapes, in which the layers are right on top of each other, have more of a connecting surface and therefore adhere more tightly. By considering this in the design, I can influence the degree of watertightness and, in some cases, improve it.

The picture on the left shows an example of a simple shape without a complex texture. The image below shows a vase with a complex texture.

To get around the problem of watertightness of a vase model, you can use a glass inner pot/vase. The advantage of this is that the water does not come into direct contact with the outside walls of the vase and is guaranteed to be watertight. However, the design of the vase will have to be adapted to the glass inner pot. In principle, this is not a problem, but it does impose some restrictions on the shape of the vase.

Post-processing

Last but not least, it is possible to finish a vase with a watertight coating of epoxy resin. Applying an epoxy coating creates a watertight protective layer that seals off any holes. This way you don't have to worry about leaks. I have used this method for some plant pots and to this day they are still waterproof and watertight.

The challenge with epoxy resin in combination with a vase is applying the coating. Especially with the vases with deep textures, it is a tough job to get the coating into all the corners. There are two options when it comes to applying the coating: a coating on the outside or on the inside of the vase.

A coating on the outside is the easiest to apply, but gives the outside of the vase a shiny layer that covers the material. If you do not want this, you can apply a coating on the inside. To do this, pour a little medium-viscosity epoxy resin into the vase to cover the first 10 cm, for example. It is important to note that it is not always easy to get the epoxy into all the nooks and crannies. Sometimes it is even necessary to rotate the vase continuously until everything is covered. In both cases you will need to let the coating harden for 24 - 48 hours before water can enter. In short: you do need patience for this option.

Is it possible to finish a vase with a watertight coating of epoxy resin?

All in all, the nature of production layer by layer brings a challenge when it comes to making a vase watertight. There are many aspects that influence the water proofing and water tightness. However, in my opinion, the above possibilities are the most promising options at the moment. For now, I have chosen to create vases purely for dried flowers, until I have found an effective solution to make my vases watertight in a simple and sustainable way.

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