Yesterday, I printed this card eight times on a single plate, every color of the game twice. I had installed a total of five 0.4 nozzles and used six colours in total. Blue and green had to share one nozzle.
So far, so good.
Printing the 8 cards took 2.5 hours. However, ironing them took 5 hours. I realised this too late and then looked at what the slicer was doing. Each individual colour is traced separately. Not across the entire card.
Is this how it’s supposed to be?
Since the entire card is not covered in one pass, the result looks pretty bad… It is not smooth, but rough and raised at the point where the colour changes. Is this a feature to prevent colours from bleeding into each other? Does this usually happen when ironing?
It makes sense that with ironing enabled you cannot cover a multicolour top surface in a single pass, because the printer is still extruding material. Each colour has to be handled by the correct filament, so it cannot just sweep across the whole card in one go. On an H2C this effectively means the printer has to switch nozzles whenever the colour changes, even during ironing, which is why the process takes so long and each colour is traced separately instead of the entire card being ironed in one continuous pass.
Since there doesn’t seem to be a sweet spot between hot enough for ironing but not so hot that filament drips out…
An ‘empty and clean’ nozzle might be a solution. But then you can generally save yourself the trouble of ironing as soon as the top layer contains more than one colour. The result always looks a bit unusable.
5 hours for that was … interessting.
Or there needs to be an option to simply allow it. These drops can usually be easily removed with your fingernail. I would prefer to iron over it with a pass and have the colour of the filament on it in places rather than something like that…
Edit: Even if a few colors might run into each other when ironing… with a checkbox and awareness of this, the issue would be resolved. Smooth > Perfect colour would have been my choice in this case.
I have not looked at the specific card referenced.
if you iron it does extrude a little amount to fill in the voids. If you have the perfect settings their will not be the build up. I have not been able to get the look I want out of ironing without the build up.
An idea that might get the smooth but does not look smooth is use a clear layer maybe very thin. assuming the clear is smooth it will still show the gaps underneath. even if it is filled with clear. What is the goal? a smooth surface, or the Look of a smooth surface. Maybe ironing the clear coat.
Another similar possible is a can of clear paint.
Maybe that is a work around, and gets you what you want. Maybe it is not the goal, and only useful for something else.
In this case, a smooth finish was the desired result. And if each colour is ironed individually, that is really no longer the case.
It’s not the end of the world, I’ll just sand down the sides and go over them again briefly with a torch.
But it simply wasn’t worth the 5 hours
I wasn’t aware that filament continues to be extruded during ironing. I thought that the hot nozzle simply went over it again to melt it.
Thank you for your thoughts.
Edit: I’ve checked the Wiki:
“The working principle is that after printing the top surface of the model, the nozzle continues to print on the model’s surface with a small flow rate at the same height, allowing a small amount of extruded material to penetrate between the lines and fill the gaps.”
Yeah … so … forget what I said about a single pass with one nozzle
Thanks for clearing things up for me guys!
However, since it was about the feel and not the appearance, I would have preferred a white veil over the entire back, for example, but with a smooth, continuous surface
Ironing on Bambu machines is not just a hot nozzle being dragged over the surface – the nozzle makes a dedicated pass at the same Z height with low speed and reduced but non‑zero extrusion, so it actively fills in gaps and smooths the top layer rather than simply gliding over it. That also means there will never be a perfect “sweet spot” where it is hot enough to iron properly but never lets any filament ooze, because the smoothing effect itself depends on both heat and a small, continuous flow.
With multiple colours on the same top surface, your observation is absolutely correct: the current implementation tends to smear colours and create small drips, so the result can look unusable if clean colour separation is the priority. An “empty and clean nozzle” pass would avoid colour mixing, but it would also break how Bambu’s ironing is designed to work, since it relies on that extra material to really level the surface instead of just reheating existing lines.
The best solution would be exactly what you suggest: a slicer option to explicitly allow ironing on multicolour top layers, with a clear warning that colours may bleed, so users can choose “Smooth > Perfect colour” when that trade‑off makes sense. In my case, for any surface where I truly care about it being clean and smooth, I would rather design it to be printed face‑down on a good build plate than rely on ironing at all.
Well, the cards are already ‘pretty’ with the face down And I would prefer the back (which in this case shows the writing mirror-inverted anyway) to be smooth (since you hold the card in your hand) rather than colourful correct.
Next time I’ll put another layer on top with just black …
Sounds like a plan. Ironing multiple colours is simply a perfect recipe for chaos. Combined with the fact that ironing is highly dependent on filament type, geometry, and various other factors, it makes it one of the most difficult features to calibrate in 3D printing.
Often solving problems like this is not about this particular situation but recognizing what the ramifications are for other projects.
depending on the material hitting with some heat after sanding helps. Sometimes it is hard to get consistent.
a few alternatives
Is the obvious clear paint.
use a flat utility knife blade to drag across the surface. Hold the blade perpendicular to the surface. Scrape the surface like shaving (not like a knife).
I have printed these cards before. On the X1C. Also multicolor—with more waste, of course. But even then, the entire card was ironed at the end.
A checkbox in the software would be sufficient. It also works with a 1-nozzle printer.
Top = H2C
Bottom = X1C
So even if it says that there is very little further extrusion… I wouldn’t say that when I look at the bottom card. You would see it, but the colors are cleanly separated—and smooth.
But then you can generally save yourself the trouble of ironing as soon as the top layer contains more than one colour. The result always looks a bit unusable.