I noticed that sanding causes my printed objects color to change (obviously), has anyone tried using an embossing gun to heat these color changed areas in an attempt to return them to their smooth darker finish?
Did it work? Pictures?
Seems make sense. I’m also curious how that would turn out…
wet sanding works better (less discoloration). also, hitting the part with a coat of clear matte varnish will homogenize the color back after sanding
depending on what you’re printing with, heat is tricky. PLA will collapse quickly without much of a transition so go light with the heat
My client wants the finished object unpainted, the filament was ordered in the color desired. So I’m limited on finishing options.
Gotcha. The clear varnish is hard to notice, but no use in going against their wishes. Try a test with wet sanding & very light gradual heat on a scrap piece. seems like it should work.
How about tumbler? Seems to work very well with metal filled filament not sure about PLA though…
https://goo.gl/photos/L4iCg1r6HJs99pbS9
So the item on the left/top was sanded near the tooth (it’s gonna be gear), the one on the bottom right is untouched.
These pieces are scrap, so after a few light passed I decided to give it a focused burst. You can see the result, it’s the circle in the middle. It seemed to work, but I held it over long out of curiosity and a bubble started to form.
I think if I spot sand the bumps needing it, I can clean it nicely with the embossing gun without much work. I’ll try wet sand paper next. But my wet paper isn’t fine.
After sanding PLA, I just go over the thing with a blowtorch. Brings out the natural color in miliseconds. Flat surfaces are better of when you use a scraper. That way there is no color change.
If you work outside or have a breather mask, Weld-on 4 can be used to recolor and polish parts that have been sanded. Also improves layer bond strength. Works on PLA and ABS, probably more.
If you hace white stress marks( like bending) hot air will take them out. You could try tumbling the print with polishing medium. But that might discolor as well.
I wonder if the varnish has any toxicity in it? I read that ABS is discouraged for kids because of toxicity and PLA is preferred.
I cut and pasted this from the e-nable site:
“… PLA is corn based while ABS is filled with potentially toxic chemicals.
Because these are being put on small children – we advise that makers use PLA because many children tend to put their fingers in their mouths and very small children may even suck on the fingers without realizing it. 
Better to be safe than sorry.”
I trust the abs in Lego more than I trust the abs in filament. The fabrication processes can leave traces of all sorts of things. I didn’t give my kid printed things until she stopped nomming everything. Now she just eats sand instead…