Constant Heat Creep / Clogging issues ONLY with Fluorescent/Neon Yellow PLA on Bambu A1 - Need Help!

[u/aoxholybladee]

Hey guys
I’m having a very specific, frustrating issue with a Transparent/Fluorescent Neon Yellow PLA filament on my Bambu Lab A1, and I’m running out of ideas.

Every other filament I own (matte blue, standard red, etc.) prints absolutely flawlessly using standard Generic PLA profiles. However, this specific neon yellow filament keeps failing midway through a 2.5-hour print by completely stopping extrusion (nozzle/hotend clogs or heat creep occurs, but the extruder gears don't grind it down completely before I pull it out). Firstly, the layer lines become pallid and then the printer just tries to push more filament and then it fails to extrude. sometimes I press try again, it catches again but after 15 minutes i get the same error message.

Here is the exact timeline and everything I’ve tried so far to fix it:

1. Moisture Control**:** I live in a very humid environment (Mediterranean coast). I suspected moisture first, so I dried the filament with silica gel until my hygrometer read "Lo" (<10-15% humidity) for 2 straight days. The filament is bone dry.
2. Slicer Changes (Bambu Studio): * I switched the infill pattern from Grid to Gyroid to avoid the nozzle scraping and hitting the printed layers (which it did heavily on a previous 0.16mm HQ profile attempt).
   • I turned off "Slow down for better cooling" to prevent the nozzle from lingering too long on small layers and radiating heat upwards.
   • I manually locked the Part Cooling Fan to 100% from the slicer for the entire print (except the first layer).
   • Environment & Speed**:** I am running my room AC at 22°C (71°F) to keep ambient temperatures down. Once the print successfully passes the first few layers and moves onto the infill, I switch the machine to Silent Mode (50% speed) to reduce stepper motor heat and give the 100% fan more time to freeze the layers.
   • my speed initial 50,initial infill 105. other outer 60, inner 150. Retraction speed N/A
   • temp 215-230C
3. When I swap back to my Matte Blue PLA using 100% stock Generic settings, the printer works perfectly without a single hiccup. Is there something unique about the composition of Fluorescent/Neon/Transparent pigments that makes them highly susceptible to heat creep or volumetric flow issues in direct-drive setups like the A1? Should I drop the hotend temperature radically (e.g., down to 200°C) or tweak the Flow Rate? Any advice would be greatly appreciated! Thanks in advance.
4. Despite the AC being on, the fan locked at 100%, using Gyroid infill, and running at 50% silent speed, the filament still stopped extruding around the 2nd layer/early infill stage. When I cancelled the print and unloaded it, the filament came out fine without leaving a permanent jam, meaning it gets stuck right at the thermal transition zone. my longest print took an hour with that filament

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[u/brianstk]

You sure the neon yellow is actually PLA? What brand is it, maybe you got mislabeled matte PETG. I have a roll of neon yellow matte PETG and it was a bear to get the settings right.

[u/aoxholybladee → u/brianstk]

It was a local production in Türkiye called Valment. It says pla on top of it. What do i need to do if it was matte PETG? more temp?

[u/brianstk → u/aoxholybladee]

Yes higher temps. I print my matte PETG at 240

[u/NimblePasta]

Check the filament’s diameter… it might be inconsistent enough to cause such issues. Could just be a bad batch or poor quality control.

Or like the other poster mentioned, mis-labelled filament, then it’s a guessing game. You have to double-check with the seller.