I have been having problems with my stirplate for the last four batches. I tried everything I could think of but it kept throwing the stir bar. I even raised the magnets up closer to the bottom of the flask. Then today I used plain water so I could see what the heck was happening and to my surprise the stir bar would not center on the magnets. I got a new bar and it centered right up. The only thing I can think of is I always boil the bar and it seems it has changed the magnetic field or the bar has demagnetized due to the neodymium magnets. From now on I will use StarSan. Does anyone have any expertise in this field?
Found this....
Stirring
If stirring stops during a reaction, all bets are off. It is very important to stir continuously throughout an experiment. If your reaction is heterogeneous, it must be stirred very vigorously to ensure efficient mixing.
If you experience problems stirring, here are some things to try:
Move the bottom of the flask closer to the stir plate.
Use a bigger stir bar.
Use a larger or more powerful stir plate (not all plates are created equal).
If your stir bar gets stuck somehow, pick up the flask and swirl it until the bar is free, or pry it free with a pipette or spatula. These kinds of reactions require constant surveillance. If you are having this kind of problem, you might want to consider using a mechanical stirring apparatus.
If your reaction is very large, a stir bar may not mix it efficiently. It might work better if you used a mechanical stirring apparatus.
Stir Bars
Cylindrical:Long and thin bars that are excellent for Erlenmeyer flasks, but may spin irregularly in a round-bottom. The short cylindrical bars sometimes fit in a round-bottom and spin fine.
Football: Bars shaped to fit in a round-bottom flask. Normally available for 25 mL flasks and larger.
Fleas: Very tiny cylindrical bars good for 10 mL or smaller flasks, vials or test tubes.
Overhead Stirring
When a stirbar simply does not do the job, mechanical stirring is necessary. An overhead stirring apparatus is typically employed. Situations when overhead stirring may be required: high viscosity solutions, large scale reactions, or in heterogeneous reactions when a stirbar becomes mired in gunky, gooey, or otherwise insoluble material.
[emoji2398]2019 Alison Frontier, University of Rochester. Supported by a grant from the National Science Foundation. NSF Funding {+} Safety Disclaimer {+}
http://chem.chem.rochester.edu/~nvd/pages/tips.php?page=stirring
I've been toying with the idea of brewing a beer of some sort from sahti malts, you can get a bag from the local grocery store here though don't necessarily want 20kg of the stuff before making a test batch first. They also sell ready made unfermented wort in many places here too you just gotta plop a dollop of yeast in and wait a while, that way it's not considered selling an alcoholic drink.
