Color Stripping.  

RE: Color Stripping.

Good evening Rene, 
some colours 'Bleed' more than others, so when you do a colourchange with MMU3, there is a default 'Purge Volume' allocated by Prusa Slicer, 

If you find a colour pair which do not purge with the default 140mm/3 purging volume, you can alter the values in Prusa Slicer

Please be aware that if you use two different materials, e.g. PLA Supports for PETG Models, you also need to increase the purging volume to ensure the mixed filaments do not weaken the model in the vicinity of the support elements

regards Joan

RE: Color Stripping.

Thank you very much for taking the time to respond.

As a test, I increased the purge volume from 65 to 150 and the results were identical. As a definite test, I split my Prusament black spool filament into two spools (to make sure the properties of the filament were identical in the two spools). I then proceeded to print the part (black background with black X), once again, the results were identical (you could see different black color bands in the picture below).

So the black on black test rules out any kind of color blending. So if this is not a color blending issue then why is this happening?

Thanks.

RE: Color Stripping.

I have not had this sort of issue myself. 

Have you considered contacting the Prusa Helpdesk Via 'Chat'? 

the Chat box, appears on this page

https://www.prusa3d.com/

about 3 seconds after the page loads. 

regards Joan

RE: Color Stripping.

Thanks Joan,

If one day you happen to be bored and are looking for something to do, would you mind printing the part to see how it comes out? Technical support is telling me that is an issue with the printer but I firmly believe that is not the case. If you do print the part you will need to print black in black using standard solid black (not the fancy one such as the one with sprinkles).

Maybe the next rainy day when you are stuck at home looking for something to do😊.

File: X_0.4n_1h42m

Thanks.

RE: Color Stripping.

I got bored yesterday, and started a print on my Mk3.9, using Galaxy Purple and white.... The White must be too old, because it's gone brittle... and broke into lots of parts. (I will try to de humidify the filament, but I don't hold out a lot of hope)

So, I re started the print using yellow instead of white  (Prusa Sample from the latest TCT360 show in Birmingham UK)
And 

There does appear to be a tiny bit of Bleed or similar...  I Wasn't able to change  the Purge settings because I only had bGcode

Hope this helps.   
Joan