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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    51 Discussions

    This is EXACTLY what I’ve been looking for! Trying to sand PLA and not only will you quickly be pulling your hair in utter frustration but you loose a lot of fine detail

    One tip: a fan with an AC filter to it will screen those cat hairs out!

    Question: when dealing with a cube print, would you recommend alternating sides in the layering steps or to finish one set of sides and then do the other set?

    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 :)

    2 replies

    it depends on layer height, the part shape and geometry and the quality you need to reach. but it's somewhere between 2-5 layers of filler.

    That seems reasonable. Had it been something like 10 or more then it would have been silly because it would start to change the shape of what you are doing and become way too thick I would think.

    Having made a few things and covered them in varnish, I was using that as a guide idea for layer thicknesses.

    Thank you for your reply :)

    If you wanted a super smooth finish, how would wet and dry sandpaper go on the polyurethane filler?


    7 weeks ago

    i think you better apply maximum number of just 2 layers of paint at the end of the process.

    according to my experience using a fan will help environment dust to sit on the sticky painted surface and is not the best idea. for this you can make an small clear room besides the fan to achieve better quality.

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

    2 more answers

    no. the strength won't be affected. this method sinters a thin layer. remember this kind of paint is not designed to be strong. but i can say it might have an amount of surface hardness if dried well.

    i tried this method with primer and paint.

    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.


    Question 8 weeks ago

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

    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.

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

    many thanks, this looks like something I will try