Overall, I’m happy with the outcome but could do better. There are several places where these smugges (See photo) has happened using 100% Bambu Lab and, in this case, the blue is Sunlu Matte mixed with black and white Bambu Basic. I don’t believe the filament is the issue.
I’m guessing the 0.4 head in the sharp pointy areas was too big. I do have a 0.2 head but I haven’t used it yet as I still a newbie.
Also, I have read that when mixing dark and light filaments it’s best to change the print order to “print lighter colors first”. Could a speed setting help?
There are generally two causes, each with a solution.
Provided this isn’t a design issue of course.
A bed with residue
Make sure to run a dry lint free cloth over the build plate before each print. It gets rid of any tiny particles you can’t easily spot.
Nozzle dragging/particles lost during printing.
Before printing, use the cog/hex icon next to the build plate and use the (currently) last two options.
You are changing the order of which filaments are printed.
The safest way is to order them by lightest first (left side) to darkest (right side).
Do this for the first layer at least, I often do it for all subsequent layers as well.
You do this by dragging one to the spot of another. Annoyingly, they swap positions, so it can take a moment to organise.
The reason this often helps is if any errant particles fall where they shouldn’t, they are covered up by later darker colours.
If it was dark to light a black particle could by u def white and appear grey. The reverse would be far harder to spot because of how colours mix and light travels.
Double check in your slicer preview that those marks weren’t put there by the computers toolpath. Sometimes using the paint tool, it can have strange decisions about how deep and how “spread out” to apply the colors, and becomes visible thru white/light colors.
Otherwise, It’s probably extra material of some description (from ooze, nozzle drag, crud, overextrusion) and the other voices are on the right track for advice. The model doesnt look to have any infill regions so any overextrusion is gonna find its way somewhere inopportune
The smudges happen because excess filament is being deposited when the blue is printed, and then white comes along and extrudes over it. You can change the filament print order, but might just end up with white smudges in the blue. You need to fix the problem with excess flow that’s leaving blobs behind.
The printer does a reasonable job of calibrating flow and PA. But a manual calibration can produce much better results.
But even a perfect cal won’t fix the issue if the issue is caused by filament oozing out when the extruder isn’t actually extruding. Any moisture in the filament will induce that behavior. If there’s only a little, the printer generally moves fast enough it doesn’t make a big difference. But if the filament isn’t dry, you can get blobs anywhere.
People often go with increased retraction to deal with this, but that’s a band-aid fix. And drying takes time. For really damp filament in a more-humid ambient environment, that time is around 24 hours. If you haven’t dried your filament, do that first.
