Hi,
I have a question about the quality of pla filament.
I bought filament from different suppliers, black and white fillament seems to be the best colors for printing (at least in my case). Red PLA color and Neon Yellow have the problem of either not sticking on the heatbed (but white / black filament is hardly to be removed) or the objects bend up at the corners. Do you also have this behaviour.
I have printed more than 15kg of different pla filaments now so configuration doesn’t seem to be the problem here.
Different colors from the same provider require different settings, but even the same colors from different providers can have different properties. It’s an exercise in empiricism. 
So you are basically saying: “I have made the same experience”
There are two factor (at least): (1) the pigments can change the melting temperature. (2) the diameter of the filament can vary from batch to batch. and even within a spool with some manufacturers.
I’ve have natural PLA at 1.75mm and 1.82. With thicker stuff, because too much was being extruded, it stuck well but walls were too thick for press fits.
@Gerald_Pirkl
Yes, but you can usually find settings that will work for a given filament. If you’ve gone through 15 kg of plastic, you probably know how to make sure your esteps are correct, at least. You should also expect to experiment with the correct temperature, print speed, and amount of cooling that is necessary to get a good print. Oftentimes these settings don’t vary much from one color to the next, but every so often they do. For me, it seems that black is different from metallic colors, and both are different from brighter ones like red or yellow. I’ve always gotten the best prints using printbl’s (Diamond-age plastic importer) silver and gold filament, which seems particularly forgiving of my choice of print temperature and speed…
There is a group of us looking into ways to make this easier and better. We have a plan, and are testing it currently (small scale) there are vendors who are interested in using this plan, but we want to make sure all of the bugs are worked out before we release it into the wild. if you are interested in contributing you can work with us in the community, or you can test it on you own and give us feed back. (the link to the git up is on the page if you have an bug to report)
http://ufids.org/
https://plus.google.com/u/0/communities/107859862288161234107/stream/bc55a66d-52ff-4453-bc98-8fc9d9df1744