How Do You Smooth Out & Finish Resin 3D Prints? – Post-Process


Resin 3D prints are great for producing high-quality prints, but many people still want to be able to smooth out and finish their resin 3D prints nicely.

It is quite a simple process to smooth out your resin prints, as long as you know the right techniques to get it done. I decided to write an article about how to properly smooth out & finish your resin 3D prints for the best quality you can produce.

Keep reading through this article for the ideal methods of how to do this like the pros.

Can You Sand Resin 3D Prints?

Yes, you can sand resin 3D prints but you should make sure to cure your resin 3D print before you start sanding. It’s recommended to do dry sanding with low 200 grit, then wet sanding with higher grits of sandpaper. You should move up gradually from around 400 to 800 to 1,200 and above as desired.

Almost all types of high-quality models produced on 3D printers can be hand sanded that will eventually remove visibility of layer lines while providing a smooth, shiny finish.

There is a misconception among people who don’t have the 3D printing experience that you can’t achieve professional quality or that there isn’t much post-processing that goes with resin 3D prints.

There are other techniques that allow you to polish your prints for a nice looking finish that works differently for different models. Some methods work beautifully for basic 3D prints while others work for more complex models.

Sanding is a great method that you should be using for your resin 3D prints, as it allows you to get rid of layer lines, support stubs, imperfections, as well as a smooth final look.

How Do You Sand, Smooth & Polish Resin 3D Prints?

If you are wondering how to finish resin prints, then you’ll want to learn the process. The process starts from preparing the models, washing it, removing supports, curing it, rubbing with sandpaper, wet sanding it, drying it, and then polishing.

When it comes to sanding resin prints, it is entirely possible to get your 3D prints to a standard where people will think it was created professionally, and not on a 3D printer at home.

Sanding is a combination of different steps that need to be followed in order to get your prints of higher quality.

The method how to sand, smooth & polish resin 3D prints is:

  • Prepare your 3D Printed Model
  • Remove Rafts and Supports
  • Sand with Dry Rough Grit Sandpaper
  • Sand with Dry Medium Grit Sandpapers
  • Sand with Wet Fine Grit Sandpaper
  • Polish your Resin 3D Prints

Prepare your 3D Printed Model

  • Preparing your model means removing your model from the printer’s build plate and then getting rid of all the extra uncured resin attached to your 3D printed model.
  • Uncured resin should be removed before moving further because it will not only protect you from coming in contact with uncured resin but may also make post-processing easier.

Remove Rafts and Supports From the 3D Print

  • Start by removing rafts and supports from the print.
  • Use pliers and clippers to remove supports attached to the print.
  • Make sure that you are wearing goggles or glasses for your eyes’ protection.
  • Start off by removing the larger support, then move towards small and then fine details.
  • Clean your model’s seams and edges carefully
  • Be careful not to remove too much material from the model, especially if there are joining points and seams.

While removing those marks on your model you can also use a Mini Needle File Set – Hardened Alloy Steel from Amazon to help out.

If you use a good slicer like Lychee Slicer and use good support settings, you can get a very smooth support removal.

On top of this, you can wash your model of resin then after it’s cleaned, put it in a container of warm water then remove the supports. Many users have praised this method to remove supports, but don’t use water that’s too hot!

Sand With Dry Rough Grit Sandpaper

  • Put on some eye protection and respiratory mask before sanding since there will be dust and particles – wet sanding significantly reduces it, but won’t remove as much material
  • Initiate your sanding process using around 200 grit coarse sandpaper – this can be lower in number depending on if the model needs heavier sanding
  • At this point, our main aim is to remove all the bumps left behind by the rafts and supports so that a clear and smooth surface can be achieved. This step may require a bit of time but will remove most of this material.
  • Clean the model after each sanding stage to see if the model’s surface is becoming uniform and smooth.

Some people have thought to use an electric sander or rotary tools, but experts don’t really recommend this because overheating can cause your 3D print model to melt and lose its shape.

You want a good amount of control and precision when it comes to sanding your resin 3D prints.

Sand With Dry Medium Grit Sandpapers

  • Sand your 3D model with sandpaper of 400-800 grit for further smoothing of the print, working our way up to that really polished look.
  • If you notice any small imperfections of parts that were previously missed while sanding with lower grit sandpaper, go back to 200 grit sandpaper and sand again.
  • Switch from lower to higher grit sandpaper as you see fit. You should notice the enhancement of the shine and smoothness of the model during this process.

Sand With Wet Fine Grit Sandpaper

  • After following the above-mentioned procedure, almost all the model’s surface will be cleaned.
  • Now sand your print with a higher fine-grit sandpaper, at around 1,000 grit, but with wet sanding. This works to offer a significant polished and smooth feel to your resin 3D print.
  • You can work your way up to higher grits of sandpaper to get an even cleaner polished look.
  • As you are sanding, you should continually check for certain spots to see if you have removed layer lines and other imperfections, especially in difficult to reach areas.

I’d recommend going with the Keama 45Pcs 120-5,000 Assorted Grit Sandpaper from Amazon. It’s a relatively cheap and should get the job done well for your resin 3D prints.

Polish Your Resin 3D Prints

As you have done all the sanding process and your print has now a smooth and perfect surface, it’s time to polish your model to get extra shine and a perfect finish. You can really get a surface that’s as smooth as glass, but it is pretty time-consuming!

In terms of sanding, you want to be at a grit around 2,000 for you to see a fairly good polished look without doing anything extra to your resin 3D print.

To get that really polished look on your resin 3D print, you have a few main options:

  • Gradually and all the way up to a really high grit like 5,000
  • Use a thin coating of resin around your  model
  • Spray the model with a clear, glossy coating

Check out this cinematic video of the sanding process by Kingsfell on YouTube.

He really goes the extra mile manages to go to 10,000 grit sandpaper to really perfect his 3D printed Master Dice, then onto 3 micron Zona paper, and finally finishes with a polishing compound.

Polishing usually works best on surfaces that are flat or nearly flat but you can also go with the spray coating option for complex structures. If you have a clear resin that you want to try to make transparent, polishing is a process that works well for it.

A great spray coating that some 3D printer users have tried successfully is the Rust-Oleum Clear Painter’s Touch 2X Ultra Cover Can from Amazon. It works great as a clear gloss surface on your resin 3D prints to give it that extra shine.

Another product that can work well to give an extra gloss or polished look on your resin 3D prints is some Thirteen Chef’s Mineral Oil from Amazon, also made in the USA.

Check out this video for a great visual tutorial that takes you through the process to finishing your SLA resin 3D prints.

If you follow the tips above, you should be well on your way to producing a seriously clean and polished 3D print that looks professional. The more practice you get doing this yourself, the better you’ll get, so get started today!

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