9 Ways How to Make Your 3D Prints Waterproof & Airtight

Creating 3D prints that are waterproof and airtight is something that many people try to achieve, or even wonder if they can do it in the first place. It’s definitely possible to make your 3D printed objects watertight when you follow the right directions.

3D printing models with a flow rate of 150%, a large layer height and a wide nozzle diameter works very well to create waterproof and airtight models. Increase your printing temperature to help layers adhere and seal up potential gaps. Seal the final model with an epoxy resin for better results.

The rest of this article will detail the process and tips on how you can get some of the best waterproof 3D prints out there, so keep reading to find out more.

Is 3D Printing Waterproof & Airtight? Can 3D Prints Hold Water?

It is possible to 3D print a waterproof and airtight object which can hold water for long periods of time without leaking. Generally, 3D prints created normally are not waterproof because there are many small gaps throughout an object due to the nature of 3D printing. You also need to have a model which is optimized to be airtight.

Most 3D prints are not going to be watertight because 3D printing creates several layers on top of each other, and in many instances, your nozzle can get slightly clogged during printing leading to imperfections in prints.

These imperfections can lead to sections having small or large holes in the model. The larger your layer height, the less dimensionally accurate your models will be which is another factor which can create a 3D print that is not waterproof or airtight.

In order to make your 3D prints waterproof and watertight, there are steps you can follow which go from picking a good model, to adjusting your slicer settings, to post-print treatment of the model itself.

The next section will go into some more details to set you on the right path to making your 3D prints waterproof, whether it is PLA, ABS or another type of filament.

How Do You Waterproof PLA 3D Prints & Containers?

To waterproof your 3D prints you should:

  • Use a known water-resistant filament which can withstand water easily and be affected by it negatively
  • Change your print settings to print larger layers
  • Increase the thickness of the exterior, otherwise known as walls or perimeters
  • Increase your flow rate/extrusion multiplier to over extrude the amount of plastic to fill up those gaps
  • Increase your printing for better layer adhesion
  • Use a wider 3D printing nozzle such as a 0.6mm or even a 1mm nozzle
  • Increase your infill percentage/density to fill the model more
  • Apply a coat of epoxy resin to seal any gaps or holes in your 3D print
  • For ABS, do some acetone vapor smoothing to smooth out any holes or gaps

Using these strategies is going to lead you to a much better path to finally create some real waterproof 3D prints, whether PLA or ABS.

It’s all geared towards reducing how many holes, gaps, and layer separations we get during the printing process, then doing some post-processing to get of any holes that may have got through the FDM, layer-by-layer process.

One amazing product to seal your 3D prints that not many people know about is the MG Chemicals Silicone Conformal Coating from Amazon.

It’s an aerosol spray which people usually use to waterproof their electronics, even having great corrosion resistance when tested in a salt spray environment. Many people use it for their 3D prints to seal PLA and ABS models.

One user said he applies 4 coats, letting each coat dry for 30 minutes before applying the next. It’s really easy to use and only requires thin coats. One of the best things is how it has no weird smell or look after it dries.

Ensure you spray in a well-ventilated area.

Now let’s get into the rest of the strategies.

Use a Water-Resistant Filament

Although you can use filament that isn’t water-resistant like PLA or ABS, you would be best off picking a filament which is.

Some good water-resistant filament to use for waterproof 3D prints are:

  • PETG
  • Polypropylene (PP)
  • GF30-PP (Polypropylene with glass fibers)

These filaments are known to hold water nicely and have a good amount of chemical and impact resistance. Polypropylene is even hydrophobic and repels water, so it’s a great choice to go with.

Increase Your Layer Height

Printing with a thicker layer height leads to fewer spaces for there to be gaps and holes in your 3D models. It essentially squishes together and makes it more likely that your prints will be airtight and waterproof, reducing your chances of experiencing leaks.

Increase Wall Thickness or Perimeters

The outer layers, or the exterior of your model are where your 3D prints will have any gaps, so ensuring that you add more material to these sections means you can make models more waterproof.

A good rule of thumb for a good airtight 3D print is to have around 2 or 3 walls/perimeters, making sure you also have a good wall thickness of at least 1.7mm. This would mean you would have around a 3.4-5.1mm external barrier to keep that water or liquid inside.

You should also have 4-6 top and bottom layers to provide even more of a solid exterior.

Increase Flow Rate/Extrusion Multiplier

Another great way to make your 3D prints waterproof and airtight is to increase the flow rate or extrusion multiplier in your slicer. This has similar results to some of the methods above, which extrudes more material to reduce the spaces between layers.

Each layer of your 3D model should have better adhesion since there is more pressure and material coming out the nozzle to connect with the previous layer.

Since we are increasing the amount of material coming out the nozzle, you would usually compensate by either reducing your printing speed, increasing your printing temperature, or both!

A flow rate of 150% should work well for making your prints watertight.

Increase Printing Temperature

As mentioned above, you can increase your printing temperature to add to the necessary element of good layer adhesion between every layer. When you have a relatively lower temperature, layers may not bond as well as they need to.

Use a Wider Nozzle Diameter

Increasing your nozzle diameter is one of the best ways of improving the reliability of waterproof and airtight 3D prints. It relates to increasing the flow rate and reducing the spaces between each layer.

Your layers will extrude much faster and thicker, meaning that it takes longer to cool down. This leads to better layer bonding because the filament is in more in the “liquid-state”.

I’d recommend a nozzle diameter of between 0.6mm and 1mm for the most optimal option.

Increase Infill Density Percentage

When you have a higher infill density, it reduces the presence of gaps in your model. This is a great way of ensure that your 3D prints are more waterproof, so use an infill density of 40-100%.

Apply a Coat of Epoxy Resin or Clear Coat

This is a great method of post-processing that clears up any slight failures in the printing process, because 3D printers aren’t perfect! By applying a smooth, clear coat of epoxy resin, it provides a thick protection against any smaller gaps or holes in your model.

People tend to apply a coat of XTC Smooth-On High Performance 3D Print Coating (Amazon) on the inside of their model to make it waterproof, then letting it dry. Once it’s dried, you should have a 3D print which is optimized for holding water or any liquids you choose to use.

It has a great rating of 4.4/5.0 on Amazon at time of writing and not only does it help with waterproofing your 3D prints, but it also provides a glossy shine to any of your models to make them pop.

When you sand your 3D models then apply a coat of this stuff, you can really get some professional looking 3D objects that you’ll be impressed with.

Do Acetone Vapor Smoothing

Creating waterproof 3D models with ABS is a lot easier due to the acetone smoothing technique. This works because acetone is a known solvent for ABS, and in some cases PLA depending on the brand and manufacturing methods.

The preferred way to smooth ABS prints with acetone is to create an environment where the ABS vapor can slowly work on dissolving each layer of the model and close up any gaps that may be present.

Use SLA 3D Printing

SLA or resin 3D printing provides a better alternative for making waterproof 3D prints due to its very fine layer heights of 0.01mm or just 10 microns. A 3D printed vase at 50 microns on an SLA 3D printer should be enough to provide you with a waterproof 3D print.

Since FDM works on heat and extrusion, the dimensional accuracy are much lesser, and presence of gaps are are much more prominant.

How Do You Waterproof a Vase?

If you have a vase made out of ABS, you can use acetone to slightly melt/dissolve the surface and clear up any small gaps where water might leak out.

Another great method that works to waterproof a vase for other materials is by using an aerosol spray. Many people have had success with the Performix Multi-Purpose Rubber Coating Aerosol from Amazon.

It is an air-dry special rubber coating spray which is flexible, non-slip, and provides an amazing durable finish.

The best thing is how it will remain flexible and not crack or become brittle regardless of any extreme conditions, even proven to work in temperatures from -30°F to 200°F.

One user got great results with printing a vase by setting extrusion width to 30% bigger than the nozzle diameter, using two perimeters with overlap (Skin Overlap Percentage) of more than 30% to completely seal the perimeters.

Best Water-Resistant & Moisture Resistant 3D Printing Filament

Every thermoplastic is reasonably waterproof as long as the manufacturing method is sound. One user who put a PLA piece in their aquarium did a 2 year update and found that it held up without showing any signs of degradation or damage.

PLA would do fine underwater, but it’s likely going to become brittle over time.

In terms of some of the best water-resistant and moisture resistant 3D printing filament out there, I’d recommend:

  • PETG
  • ABS
  • Polycarbonate
  • ABS (acetone smoothed)

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