How to Achieve Mirror Finish in Large Format FFF Prints
If you have seen one of the 3DP’s large print samples in our image gallery, or at one of our recent trade shows, you might have noticed that a number of our large 3D print samples are displayed half as-printed, and half post- processed.
“Why do you finish only half of it, and how do you make it look so shiny and smooth,” you may wonder.
The purpose of finishing half of a 3D printed part is to show the various post processing techniques that can be applied to 3D printed parts, and the stunning finish that everyone can easily achieve, by adopting a few simple post-processing techniques. In this blog, we are going to introduce the 3 simple steps to achieve mirror finish in large format FFF prints
First and foremost, remove all support structures from the 3D print, deburr and remove all sharp edges of plastic that may be remnant from the support structures. If there are still rough areas, lightly scuff with 400 – 600 grit sandpaper or Scotchbrite.
Using support structures is the key to successfully printing models with steep overhangs and cantilevered sections. If a model requires support structures, there are many methods to build supports in order to save time and material. To learn more about how to use support structures in 3D printing, please read our previous blog, or watch this short video.
The second step is to apply one coat of adhesive promoter to the 3D print surface. For PLA material 3D prints, we suggest PPG’s plastics adhesion promoter DPX801. The DPX801 is a universal plastics adhesion promoter, which is a transparent product specially designed for use on automotive bumpers and various plastic parts to provide adhesion on these substrates for subsequent topcoats. To ensure the best result, make sure you have properly cleaned or sanded the part before apply. After completing the first two steps, let the 3D print dry under room temperature for at least 30 minutes, but no longer than 24 hours.
For more details about DPX801, please visit the link here.
The third step is to apply one coat of High Build Primer to achieve an ultra-smooth surface finish. PPG brand High-Solid clear DCU 2002 drys relatively quickly for use with multiple coats. Another primer suitable for this step is the Transtar Euro-Classic 7241. Both primers are quick drying and easy to sand wet or dry. Once the primer is dry, the 3D print should look pretty smooth. Apply additional coats until desired smoothness is achieved. You also have the option to apply paint for a more artistic finish.
Step 4 (Optional):
If you think the above techniques are still too complicated and prefer not to sand your 3D prints, here are two simple solutions:
Apply four coats of High Solid Concept Clear DCU 2002 over the non-sanded 3D print. (For best result, prime the print with DPX801). Once the coat is dry, your 3D print will look glossy and still shows the original as-3D-printed texture underneath the clear coat.