Stringing black in white parts

I have a P1S, Sunlu filament. Trying to print some lightboxes.

On the Lego one i have 0 issues with small black string are in the white parts.

With other prints, like this Harley one (Harley Davidson Lightbox LED Lamp by braga3dprint - MakerWorld) i have black strings in the white parts. You cant see them clearly, but when i put a led in, its very visible.

Using the settings provided by the maker( Thanks btw).

Any ideas where to tweak?

What order do you have the colours set to print in? My guess is that the Lego has a different order than the Harley one.


Noob here, where can i check that?

Click the Gear/Nut icon next to the Plate you have selected on the Prepare screen.
“First Layer Filament Sequence”

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Lego = white-red-yellow-black
Harley =White- orange-black

Since you’re printing white first, it’s not likely the strings are from the black of that print.
Could they be something left on the build plate?
What plate are you using and do you clean between prints?

Thanks again for your answer!

Textured plate. I clean after every print with soap en sponge, then with 99% alcohol.

I’m not sure what’s going on then.
What pattern are you using for the first layer?

Could they be some kind of fibers left from the cloth you use to clean the plate?



I tested twice with lego, no strings, then harley, strings:)

Try increasing the Flushing Volume, my guess is that the black isn’t fully cleared when going back to white…and stringing on the 2nd layer.

EDIT: Also, are you using a purge tower…??

What I have done in the past to ensure I am getting a clean white first layer. Along with a thorough cleaning of the physical plate is add a new plate in Bambu studio, add a primitive cube to that plate set to 50mm x 50mm x .2mm and print that, verify that it’s all white, if not I print again. after a clean print I proceed to print the model making sure white is the first color to print.

Yes. And reviewing that part, i see some black in the white.

I will try this! Because the previous print ends with black.

Will update, thanks!

I preheat my nozzle before the print and wipe anything left on it while heat up to get dark colored residue off from aound the nozzle tip when I plan on printing w white and need it to be clean. That is most of the time the culprit of your problem

Thanks! See photo of the residu coming from only pre heating and cleaning:)

I also print a cube to test, full white!

So now printing the Harley again, and test.

Then the question will be, do i have to print a clean cube everytime, or is pre heating and cleaing enough:) So 2 more tests to go:)

Theoretically it should be fine w just wiping the tip clean. I get black blobs like these on light colored or even transparent prints like this even after 4-5 prints between black and these w residue on them. The problem imo isn’t that there is leftover filament inside the hotend but between the silicone and the nozzle tip. Attached pic of said black (pla) residue on a petg vase print, which was printed 4 models after the last usage of black pla. Nozzle wiper is useless, I’m waiting on my a1 wiper silicone to come to mod my p1s wiper, they are much better (I heard)

Is there a link to this mod you can share, please?

Shoot me…

After the very clean white cube, again this:) some black in the white letters…

What I was suggesting was a large flat square .2mm high should be one layer high, if you cover the area of the build plate you will be printing your model on it might detect any contamination of the build plate that you could not see after cleaning. I am not sure what is causing your issue, I have printed several multi color logos without that type of contamination. Maybe try a different brand black filament.

Try lowering the print temp of the Black only by 5-10*.

I eally, really clean the plate. With soap and a spons, then 99% alc. There is really nothing left. I cant see the string on the first layer too.

will try!

will try too;)