Beware MG Chemical PLA!

I was printing fine with blue 3mm PLA at 210 C on my delta but ran out and bought a different brand from the local store, MG Chemical Navy Blue (original was from a second pack so unknown brand).
It started jamming almost immediately!
After eliminating everything else I cut a small piece from the old and the new and put them in a cast iron skillet and turned it to medium whole pressing down and rolling them with the tip of a table knife. The new stuff started getting real soft, almost like a gel, long before it started to melt, unlike the old filament. They both seemed to melt at the same rate and viscosity. If I am pushing it hard into the hot end it is no wonder why it fails.
YYMV so let me know if you have different experience (hopefully in a similar setup ie 3mm Bowden)

edit:
Just bought and did the skillet test with Shaxon filament from Fry's: similar to my original stuff although it looks it might require a little hotter hotend but that is the kind of variance I expect)

It seems the new MG filament needs a short transition zone and/or lower temperature. ( 210°C seems pretty high, but I have no experience with 3mm filament )
It´s usual business to adapt your printer to new filament. Start with low temps and feed it manually to get a feel for it.
If possible use a spare hotend with a big nozzle ( 0.4-0.5) for the manual feed, it´s easier to maintain when you jam it.
-Olaf

Edited 1 time(s). Last edit at 09/13/2015 03:09AM by o_lampe.

The last time I made an attempt to push it in by hand it just jammed. I of course thought to lower the temp, which actually made it worse because all it did was gelify and squish out directly into the wall of the heatbreak. Watching it turn into a squishy gel (in the skillet) well before it started to liquify is not what I would call a good design. It should go from hard to liquid with as little in between as possible; the exact same state desired for the transition zone of the hot end.

I found the skillet test a better way than the extruder to get a feel for the properties of the material where I could pinch and squish and slide it around while the skillet temp rises, especially comparing a known good material with an inknown side-by-side. No suffering from endless hotend tear downs and rebuilds where you have to guess what is going on (assuming your hardware is in good shape).

Did you ask MG chemical for a refund or any advice?

Hmmm.. interesting idea. I was thinking of them as a generic label. Most places that sell this quality don't take refunds once open and used. A refund would be nice.

One other observation of this material: I say 'gel-like' because it becomes transparent in that intermediate state.

olampe, thanks for the suggestion. I sent a detailed email to the tech support at MG Chemical; we will see if they bother with one user.
While typing I started to realize that they may sell ok because the lowest common denominator printer style is cartesian/teflon-lined hot-ends, which might allow it to function.
(it still seems like it has horrible properties).
The seller at Fry's Electronics told me they get more customer complaints about this brand than the one I bought. Prices are not that much different, albeit MG has smaller spools.