With some filament, mostly black PLA in my experience, the first layer infill gets distorted. I think this is because of the slow(er) movement of the hot end.
This black filament does need the slow speed for the first layer perimeters to get a good stick, just not for the infill. Subsequent layers do get a good print for infill, partial infill and perimeters.

Is there any setting I overlooked in Slic3r that allows me to keep the perimeters slow on the first layer, but speed up the first infill?
Or can you suggest other methods to improve my first layer with black PLA?

Thanks if you could help me out!

Isn't that the "solid infill" parameter in the speed settings? It appears you can adjust that.

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Waitaki 3D Printer

That parameter is for every layer. The issue I am facing is that I need to fine-tune the speed of perimeters and infill separately for the first layer, but I can't find any way to do that.

The 'solid infill' you are referring to is for all layers, not just the first layer. There is however a speed adjustment for the first layer as a whole, but that also would speed up the perimeters and I can't have that.

Ideally the speed tab with 'speed for print moves' would contain 2 columns for first layer and subsequent layers. The parameter 'first layer speed' isn't helping all that much because it doesn't allow fine-tuning. Hopefully this will be possible in a future release.

...I'd put more effort into describing and discussing the problem before coming to a proposed solution. Pictures, videos, observation, whatever helps people understanding what the problem is. I don't really get what do you mean by "the first layer infill gets distorted".

Personally, I set the First Layer Speed option to 30mm/s, so that everything on the first layer gets printed at that speed, regardless of things being perimeter, infill or anything else. That works nicely, especially when combined with higher temperature, higher bed temperature, first layer height, first layer extrusion width: you can read all of this at [manual.slic3r.org]

Thank you!

Actually, I'm confused by your reference to "infill". The first layer has no infill, its a solid layer - is that what you are referring to?

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Waitaki 3D Printer

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The first layer has no infill, its a solid layer - is that what you are referring to?

I'm sorry for the confusion and yes indeed that is what I meant; the first solid layer.

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Personally, I set the First Layer Speed option to 30mm/s ... regardless of things being perimeter, infill or anything else

That is exactly the thing I wanted to avoid. I have tried many different filaments from different suppliers and while most print perfectly fine, there are some, especially black, that behave a bit different then others. In this case I'm referring to black PLA filament which I can get to create a nice thick first perimeter, but looses it's cool (pun intended) when creating the first solid layer within the first perimeter. And I think this is caused by the slow movement of the head that heads up the layer. Speeding up the first solid layer would solve that, but that would also speed up my first perimeters and that won't stick and results more than often in a failed print.

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I'd put more effort into describing and discussing the problem before coming to a proposed solution.

I think you may be right; I should indeed try harder to get it to work without asking for changes that isn't the easiest path to begin with. And so I did try something that is counter-intuitive for me at first sight: trying blue tape with a cold bed instead of keflon tape with heating. And to my big surprise this actually solved my problem . It's pure logic because of my necessity of eradicating excess heat, but as my Huxley is designed for a heated bed I'm surprised that simple cold blue tape is actually much better. Even my bridges seem to be near perfect now! Maybe with time I will get to learn situations in which a heated bed is helpful, but for now I will just stick with blue tape.

Thanks both of you for your replies!

I have exactly the same problem with black PLA, i think the problem is that black PLA retains heat and stays soft for much longer after being extruded than other colors. Its also possible that its re-absorbing infrared radiated heat from the nozzle as it passes close to it again, the black color would result in it absorbing energy at almost any frequency (its why summer wear is white). so that if it is still soft from being extruded and the nozzle makes another pass very close to it, it will liquefy or soften again, if its just close enough. I can see a strand that has been laid down perfectly good and appears to have good adhesion, lift and twist when the nozzle passes close to it again on the return stroke of a solid fill. I can see this happen even if it does not touch.

I have a USB microscope, so i'm going to try and lash-up a rig where i can attach the scope to the machine and video what is going on at the nozzle end, so i can see exactly what is happening.

One possible help is to increase cooling, black PLA does not seem to need cooling off on the initial layers to get good adhesion, so having cooling enabled from the start may help. I have a desk-fan pointed at my build platform, and it does seem to help.