I have an H2D modified for TPU printing (TPU Feeder and Nozzle). I have a 3D model that combines TPU and a light brown PLA. The adhesion has worked great on Black, White, Brown, and Solver/Gray TPU (Hundred of successful hours of printing). However, the light Blue TPU (bought from Bambu, same 95A as the other colors) seems to print a LOT thinner and the brown PLA seems to have trouble adhering. Asks: Has anyone else had to adjust settings based on the Color of TPU being printed or seen non-base color TPU extrusions differences ? Thanks in advance.
There are too many unknown variables. In theory, colour shouldn’t make any difference at all. However, other factors come into play.
- Bambu doesn’t produce the filament itself, so it’s impossible to know exactly which factory it comes from. Different colors, different production facilities, or maybe not - no one knows.
- This includes different production batches and how the filament is handled during production and shipping.
- How you store the filament, its initial humidity levels, and whether it was exposed to sunlight, among other considerations, can influence its performance.
Just to compare, did you dry your filament beforehand? I usually hold back on giving tips like drying filament, but TPU? You should definitely do it.
Just a tip: The last user who had exactly the same problem as you found out that his nozzle was worn out. I just wanted to mention that. It started out exactly the same way for him - certain colors were causing problems, and he thought it was because of the colors, when in fact the nozzle was simply faulty / worn out.
Yes, all filament are in AMS’ and were below 35%. I have had issues in the past and keeping them dry eliminates a lot of variables. And it never hurts to cover the fundamentals first (e.g Did you turn it on 
I thought about that but when I back printed another batch with the colors that worked, I did not have the issue.
Like I said, I’d just quickly swap out the nozzle - that’s the fastest way to check and see if the problem is gone. While we’re on the subject of nozzles:
Here’s a guide that includes a few more essential tips. Complete tips in the guide; here is a shortened version
- Special attention must be paid to nozzle selection when printing TPU filaments.
- For printing TPU filaments, it is recommended to use brand new nozzles, or cold-pull old nozzles before printing. Please refer to the Cold Pull Guide for instructions.
- Nozzle history matters.
What kind of nozzle do you use? How long have you been using it, roughly? Do you use different nozzles for TPU and PLA? Do you clean the nozzle using the cold pull method?
These are all factors that could come into play.
Like I said, I’d just quickly swap out the nozzle, test it, and then let you know how it goes. That way, we can rule out a lot of possibilities right away.
TPU and PLA do not bond together very well. I have used PLA as a support material for TPU because it is easy to remove.
I am using the Bambu TPU Nozzles. I have been going back a forth using different color TPU but same TPU Nozzle. Only the blue is causing the issue.
I haven’t had any issues binding TPU with PLA. I have printed roughly 1000 units with very few issue except when using the light blue.
@RetroSharky I think you are right, the TPU must have some different manuf properties and probably came a different batch. I use a TPU AMS and feeder with TPU Nozzles. When I swap back to the other colors with the same nozzle they print fine. I may try a different spool of the same color.
That probably requires much re research then.
I personally had a very poor adhesion issue with red PLA Basic onto a textured build plate. Drying and washing the plate with Dawn soap didn’t work.
Eventually I solved it with just onle layer of black PLA and the rest wit red, and the part printed beautifully. Ans the black wasn’t visible after assembly I stopped further research.
Maybe worthwhile to dig into this again.
It seems that certain pigments strongly influence the behavior of the filaments.
So your lis might eventually be extended with color as an influencer.
As @blchandl2 already mentioned, normally TPU and PLA don’t really bond very well.
I use PLA as support for TPU also, but I must admit that certain colors of PLA act differently on adhesion. But I can’t say for 100% that this is related to color, as moisture content is the PLA might have an influence also.
Although I never tried it, PLA Matte might give even better adhesion as the surface texture is slightly rougher than PLA Basic.
I definitely recommend to dry your filament thoroughly. 35% humidity in the AMS is quite high imho. Mine is usually around 15%.
Right, exactly.
That’s why I said “in theory.” Because to measure that in practice, you’d first have to rule out all the other factors I mentioned. It would likely fail simply because the company itself can’t rule out fluctuations, so you wouldn’t get accurate samples.
The measurement is only as accurate as the company itself can guarantee that it will send it to us in good working condition. The lab and the company would essentially have to be right across from each other and work together to compile such a list.
At least that would be my first thought, which I wanted to share with you now. 
I have noticed Bambu Silver Silk PLA is stronger than the other colours of Bambu Silk PLA.
It is possible one of the colour additives changes the properties.
It is also possible that some colours come from different factories.
EDIT Another related story: Games Workshop’s original “devlan mud” (I think; it was the brown one) wash (a type of very thin paint similar to an ink) used an organic chemical that the others did not, which resulted in the paint decomposing. After a few weeks in the pot, it began to froth and produce a vile small of decay. So, yes, the colouring additives (pigments) are not necessarily the same for every colour, and do not necessarily confer the same properties to the material.
Regarding the theory. I am a plastics process engineer and we absolutely do (on occasion) alter process parameters due to changes in colorant when it comes to high precision molded parts.
Titanium dioxide, a common white pigment, has a very different thermal conductivity than carbon black, for example. Even the grade of each matters and it’s possible to find grades which have the same TC (or ‘k’ if you are a turbonerd) value.
In practice this is less pronounced because we don’t mold 100% pigment of course.
This will have a measurable effect on how quickly any polymer will melt, and is more impactful at higher load ratios. Likewise other pigments will cause small changes as well.
Practically speaking I really doubt the differences matter for any of our 3D printed parts, but I wouldn’t be surprised if it does.
But high moisture content will also absorb a lot of that heat energy and change things too, plus the other mentioned things which will impact print quality.
Of note is the other filament may be an entirely different grade of the polymer with wildly different properties altogether, but that’s a quality control issue if Bambu is outsourcing filament production - but they should know better than that.