Regaining Sanded PETG Colour: Heat Didn't Quite Work for Dark Parts...

Continuation from this Post: https://lemmy.blahaj.zone/post/36954883

After many of you Suggested that Heat could be a Potential Solution to Regaining Sanded PETG Colour, I got myself a Heatgun Capable of 600c°.

While it did Improve the Colouring, Especially for Darker parts it wasn't Enough. To be a bit more Specific, Both Green and Yellow Parts Fully did regain the Colour Red Improved a Lot, but not quite Satisfactory And Black did make a Difference, but its not Nearly Close enough, being a Matte Dark Gray instead of... Black

I've noticed that the Black only did regain its true Colour once actively Melting and Warping which doesn't help... Otherwise its a Light/Dark Gray Matte Black.

So I think the Heatgun Method doesn't quite hold for Dark Parts. What other Methods of Regaining Colour are there?

I do still have MEK that I could Try. I also Heard that Clearcoat could Work and that there are 3D Printing Specific Brands, should I give that a Shot?