Very good info's.
There is indeed a lot of difference, at last now i know why.
The most expensive one that i bought: 41 euro for 500gr.
Is not really good for soldering on the cells, it "splashes" to much and give a lot of small tin drops.
This one i only use for the neg side, til i run out.
The most cheapest one, comes from China, 12 euro incl shipping for 500gr.
I does not have so much resin in it but just enough to let it flow.
You can clearly see the eutectic state when the metal is "freezing".
Both where printed 60 lead 40 tin.
The one from china leaves also nearly no residu from the resin.
It takes a bit longer to make it melt.
I think i stick to this one.
I also going to order the one from the amazon link.
I also had one with 2% copper in it, to save on your tip, my iron was not getting hot enough for it
@not2beme.
I like your pictures, but for you good one, i prefer a little bit more solder.
Your 2 first picture's, well...that how i started, to be honest.
Very quickly it become a nice shining flat drop.
Thanks
I noggtnot2bme2bme