After Having experimented in Making Perfectly Smooth Surfaces for about a Year now within the Print Process itself, Its time I Capitulate and start putting in some more Work and Sand it all smooth!
Just a bit of an Issue… Whenever I sand Coloured PETG, it looses its Colour and turns into that Broken Plastic White.
As someone who hasn’t had to Fix something like that before, I’m not sure where to even start Fixing this? Can it be Avoided in the Sanding Process, or can the Colour be Regained afterwards?
I have heard of People Treating it with Heat and Vasaline to get the Colour Back, what kind of Methods do you all use and how reliable are they?
Have you tried epoxy resin? No sanding and layer lines disappear with shiny finish looks
There is a product that is used to restore car headlights.
The clear plastic on headlights gets foggy and yellow over time.
It’s not expensive. You can get it online. Lots of names and brands.
I used some on pla and it did make it look like it had not been sanded.
I actually documented it.
So here you go. https://imgur.com/gallery/J01PA0o
I’ve polished to a practically mirror shine with progressively finer and finer grit sandpaper. Took an eternity. Worked for the purple I was using, but it might not work for all colours.
I’ve also tried heating PETG with a butane lighter out of pure frustration. It does work, but the line between restoring the surface finish and deforming the print is very thin.
I see, thats quite interessting… I do wonder since my Main Concern are Flat Top Surfaces, if putting the rough Print surface on a Heated Surface of Sorts would do something simular? Thinking like a Heated Pan or Metal Sheet?
I just use a heat gun or a quick pass with a torch. Sanding makes small imperfections that light reflects into, giving it that matte look. Heating it melts those little scratches back together so it reflects light properly again
The Prints I’m working on at the moment are rather small, I think a Torch or Heatgun could also melt other spots that aren’t supposed to be melted because of needed Surface Patterns… I wonder if there is something a bit more Controlled?
There are lighters with a blue flame, these work quite well and controlled.
Practice on a scrap piece.
How fine are you sanding it? Coarse sandpaper makes the PETG turn white and fuzzy. That goes away after wet sanding with 400 to 600 grit. I usually go up to 2000 grit to get a smooth surface. The color is still quite a bit lighter after sanding though.
I have been using more Coarse ones thus far yes… I do wanna achieve the same colour as the original Plastic tho
a MEK vapor bath would likely give you a smooth finish. But, Uhm, personally the raw print is probably preferable as MEK is some nasty shit. (not so nasty you can’t buy it at your local big box hardware store, but it’s not something you can just pour into a kitchen pot and be safe around.)
it would work similar to an acetone vapor bath for ABS.
Soooo I did actually try Vapor Smoothing with MEK Before! Infact I still got a Litre of that Stuff Around now, but even after leaving the print in there for Days at 50°C the Results where… honestly no big Changes at all…
I do suspect there is an Error in my Methodology… but turns out there isnt a lot of Info out there on Vapor Smoothing with MEK… Have you used MEK for Vapor Smoothing before?
I’ve not used MEK personally, all of my petg parts are structural. What I’m seeing online says 60-80c.
What I’d do is kick it up by 5c at a time.
swap in failed test prints and see how that changes things. Keep in mind if you stay in the cold range and give it more time, it might create a better finish.
Too hot and it’ll start melting.
Maybe also “priming” the chamber with a heat gun so the air is also warm. (Do this before placing the MEK!)
Also, a small hole someplace that’ll get covered and a toothpick to lift the part will help retain its shape.
I habe never used mek, but acetone on abs. Works like a charm.
