Easy Way to Smooth PLA | No Sanding





Introduction: Easy Way to Smooth PLA | No Sanding

First of all, Thank you for checking out my tutorial! You are awesome.

Second, I put a lot of time into the YouTube video so watch it too, it explains it all.

So currently, there is no easily accessible chemical to smooth PLA the same way acetone does to ABS.

But here I will show you how I fill in the layered build lines.


Step 1: Materials

You will need:

A 3D printed model with visible layer lines.

Any can of spray paint that bonds well to plastic.

Fast Drying Polyurethane - Clear Satin.

If you like this skull you can download it here: https://www.thingiverse.com/thing:2951822

Do read and follow all safety warnings on all spray cans and 3D printers.

Step 2: The Magic Steps

First clean the model of any dust and make sure it's clean.

Next spray the model with your selected color of spray paint.

Then quickly spray a layer of Polyurethane.

Then place it under a fan to prevent drips and to make dry faster.

The paint and Polyurethane will mix and fill the layers, any holes, and printed flaws.

The thinner each layers and the longer you let each layer dry the better.

I waited 20 minutes between layers and then waited an entire day before spraying the final coat of spray paint to cover any discoloration.

Step 3: Finished!

And that's really it!

I like this method because you can print in larger layer lines without worrying and it will print much faster,

you can print in any color and paint the final color you want, it doesn't need sanding, it can fill holes or flaws, and its pretty easy to do.

Note: I did print the skull at a layer height of 0.3 which means detail was lost during printing. A height 0.1 would have been better and taken less time to smooth but I needed an extreme layer height to show how much this method can do!

The final result looks much cleaner and more professional. People wont believe it's 3D printed!

Feel free to check out my YouTube channel - 3DSage. I create lots of different and fun videos!

Thank you and see you next time!




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    3 Questions


    What is the brand of filament you used? I tried it with Meltink3d pla. Didn't work very well.


    Will this method work with ABS as well?


    Yes! The mixture of polyurethane and paint will fill in the layers of any filament. Maybe not flexible filament but definitely ABS.

    1 more answer

    If the paint and polyurethane stick, then it will work. I think this method is pretty universal for smoothing just about anything, I used to use a very similar method while staining and finishing wood.

    Does this technique have any effect on the strength of the piece? I'm wondering if it makes the surface a bit tougher.


    I didn't think about the strength changing. That is an interesting idea. Maybe a little but I am not sure by how much. I think of this method for more decorative pieces instead of under stress and pressure.


    You could just use a sandable spray primer. It is designed to do exactly what you ae trying to accomplish. You can sand it if you choose for an even better finish.

    2 replies

    I have done both techniques and spray primer doesn't come close to the results without extra work.

    Yeah. I think that a spray filler would be a bit cheaper (at least where I live) than PU-clear coat.

    The very reason I have not gotten into 3d printing is because of "dangerous" chemicals. Unlike some of the comments here I understand the risk involved and this is the lowest risk.

    I do have one question however.

    How many layers did you use to fill in all of the gaps?

    Not including the last layer the next day.

    Thank you :)

    haha he's always an inspiration to me! Thank you.

    of course, I'm glad I could be helpful!


    Di you tried just spariyng poliurethan paint?

    1 reply

    No I haven't but since it's clear, I felt like i needed the paint to mix in there too so I can see when the layers are filled.

    Thank you so much!

    Thanks so much for this information and the video. I have been printing and when I wanted to I sanded the parts to smooth them some but what a pain. The spray color and the poly sounds and looks great. Thanks so much! Tony

    1 reply

    Thank you very much! I totally agree about sanding being a pain! I hated it. It can be almost impossible depending on some shapes with close raised details or deep sockets like the nose of this skull. But anyways feel free to try this method! Have fun 3D printing!

    Thank you for posting this! This is really a great solution. PLA is so gummy you can't really sand it and the harsh solvents don't work well either. This is a great solution using common items that can be had cheaply.

    1 reply

    I would recomend random spray filler, they gives the same surface, but its sandable and paint sticks better on it.

    I think you have best results submerging the piece.

    Best I've seen for painless PLA smoothing, Thanks!