<p>Yes.</p>
<p>The issue is, that there are small gaps between the layers. But you can coat the print in an airtight material. While epoxy and similar materials work very well, they are somewhat too viscous and take a long time to cure.</p>
<p>My special recipe for coating PLA prints with a fast-curing airtight thin layer is:</p>
<ol>
<li>Dissolve 1 g Paraloid B-72 in 20 ml acetone.</li>
<li>Dip or otherwise evenly coat the print and dry at room temperature for 10-20 minutes.</li>
</ol>

CC BY-SA 4.0
2022-06-12T13:07:26.850Z
Most PLA has additives that acetone attacks. How do you deal with that when performing a long dip? Do you get special additive-free PLA?
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2022-06-12T14:24:52.060Z
I use AmazonBasics PLA and dip for about 10 seconds. That's sufficient, because the fluid is very low viscosity. I did not notice any issues.
iblue
CC BY-SA 4.0
2022-06-12T12:11:02.863Z
2022-06-12T14:57:26.347Z
2022-06-12T14:57:26.347Z
iblue
<p>In theory, yes you can without any additional materials. But it requires a very high level of perfection for your 3D printer's output.</p>
<p>&quot;Gaps between layers&quot; are not the issue. There is no &quot;gap&quot; between the extrusion at layer N and an identical-path extrusion at layer N+1 if layer N+1 is extruded correctly and remelts the surface of layer N sufficiently to bond everywhere. There are <em>grooves</em> between layers from the extrusions not having perfectly rectangular cross-section and rather slighty rounded edges, but these are not &quot;gaps&quot;.</p>
<p>Where gaps do come in to play is from inconsistent extrusion. If at any point the printer fails to resume extrusion where it's supposed to, or extrudes slightly less material than it's supposed to, there's a possibility that the complete remelt/bonding described above does not happen. It's also possible that grooves <em>turn into gaps</em> under high pressure, by providing a surface where the pressure can act like a wedge to separate weakly-bonded layers.</p>
<p>Also involved here are issues with the filament quality. If the filament contains air pockets or has absorbed moisture, there will be tiny bubbles bursting in the extrusions, making a potential path for air to pass through.</p>
<p>I have not succeeded in producing an air-tight container, especially not at high pressure, but I have made test containers for a vacuum that take several minutes to return to ambient atmospheric pressure after the pump is removed. This was using PLA with a non-high-temperature-capable hotend. I'm planning on revisiting this at some point with the temperature cranked way up (now with all-metal) with PLA and other materials to see if there's any practical viability to the theoretical possibility of getting it right.</p>
<p>Short of that, iblue's answer to use an airtight coating is a great option if you can deal with the dimensional changes or compensate for them in designing your parts.</p>

CC BY-SA 4.0
2022-06-12T14:29:09.857Z
Have you tried it? I pressurized my print and put it into water. It bubbles all over the surface. If there are no gaps between the layers, where does the air come from? Also, the dimensional changes seem to be small. I have not measured it, but the threads work as before.
iblue
CC BY-SA 4.0
2022-06-12T16:28:27.073Z
@iblue: My answer states what I have and haven't tried as well as several plausible explanations for where gaps exist.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2022-06-13T16:50:57.260Z
Curious if adding more wall lines improves this.
Joel Coehoorn
CC BY-SA 4.0
2022-06-13T16:53:14.027Z
@JoelCoehoorn: I used a large number of walls such that the part was entirely walls (no infill area) and Cura 5 which uses variable wall line widths to avoid leaving any gaps.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2022-06-13T22:37:17.290Z
I have to interject a word of caution here. 3D printed materials don't have a lot of tensile strength and layer to layer adhesion is the Achilles heel. If pressurizing a 3D printed vessel it would be prudent to hydro test to at least 125% of the intended working pressure.
allardjd
CC BY-SA 4.0
2022-06-12T13:06:29.740Z
2022-06-12T13:06:29.740Z
R.. GitHub STOP HELPING ICE
<p>I printed a G1/8 thread in PLA where I can connect a compressor to have a small pressure container. Even though all measurements are correct and it screws in fine, it still leaks air.</p>
<p>Is there a way to make 3D prints airtight?</p>

CC BY-SA 4.0
2022-06-17T21:45:59.617Z
Did you try Teflon tape around the threads?
ChinchillaWafers
<pla>
Is there a way to make my 3D prints airtight?
iblue
# Is there a way to make my 3D prints airtight?

(Asked by: username_0 on 2022-06-12)

I printed a G1/8 thread in PLA where I can connect a compressor to have a small pressure container. Even though all measurements are correct and it screws in fine, it still leaks air.

Is there a way to make 3D prints airtight?

**Tags:** pla
> **Comments:**
> **username_1**: Did you try Teflon tape around the threads?  

---

## 2 answers

### Answer by username_0 on 2022-06-12. Score: 5

Yes.

The issue is, that there are small gaps between the layers. But you can coat the print in an airtight material. While epoxy and similar materials work very well, they are somewhat too viscous and take a long time to cure.

My special recipe for coating PLA prints with a fast-curing airtight thin layer is:

1. Dissolve 1 g Paraloid B-72 in 20 ml acetone.
2. Dip or otherwise evenly coat the print and dry at room temperature for 10-20 minutes.

> **Comments:**
> **username_2**: Most PLA has additives that acetone attacks. How do you deal with that when performing a long dip? Do you get special additive-free PLA?  
> **username_0**: I use AmazonBasics PLA and dip for about 10 seconds. That's sufficient, because the fluid is very low viscosity. I did not notice any issues.  

---

### Answer by username_2 on 2022-06-12. Score: 5

In theory, yes you can without any additional materials. But it requires a very high level of perfection for your 3D printer's output.

"Gaps between layers" are not the issue. There is no "gap" between the extrusion at layer N and an identical-path extrusion at layer N+1 if layer N+1 is extruded correctly and remelts the surface of layer N sufficiently to bond everywhere. There are *grooves* between layers from the extrusions not having perfectly rectangular cross-section and rather slighty rounded edges, but these are not "gaps".

Where gaps do come in to play is from inconsistent extrusion. If at any point the printer fails to resume extrusion where it's supposed to, or extrudes slightly less material than it's supposed to, there's a possibility that the complete remelt/bonding described above does not happen. It's also possible that grooves *turn into gaps* under high pressure, by providing a surface where the pressure can act like a wedge to separate weakly-bonded layers.

Also involved here are issues with the filament quality. If the filament contains air pockets or has absorbed moisture, there will be tiny bubbles bursting in the extrusions, making a potential path for air to pass through.

I have not succeeded in producing an air-tight container, especially not at high pressure, but I have made test containers for a vacuum that take several minutes to return to ambient atmospheric pressure after the pump is removed. This was using PLA with a non-high-temperature-capable hotend. I'm planning on revisiting this at some point with the temperature cranked way up (now with all-metal) with PLA and other materials to see if there's any practical viability to the theoretical possibility of getting it right.

Short of that, iblue's answer to use an airtight coating is a great option if you can deal with the dimensional changes or compensate for them in designing your parts.

> **Comments:**
> **username_0**: Have you tried it? I pressurized my print and put it into water. It bubbles all over the surface. If there are no gaps between the layers, where does the air come from? Also, the dimensional changes seem to be small. I have not measured it, but the threads work as before.  
> **username_2**: @iblue: My answer states what I have and haven't tried as well as several plausible explanations for where gaps exist.  
> **username_3**: Curious if adding more wall lines improves this.  
> **username_2**: @JoelCoehoorn: I used a large number of walls such that the part was entirely walls (no infill area) and Cura 5 which uses variable wall line widths to avoid leaving any gaps.  
> **username_4**: I have to interject a word of caution here. 3D printed materials don't have a lot of tensile strength and layer to layer adhesion is the Achilles heel. If pressurizing a 3D printed vessel it would be prudent to hydro test to at least 125% of the intended working pressure.  

---

