Magnetic Stirrers, anyone using one?

[Robert Ley]

I am considering getting a magnetic stirrer for mixing dark room chemicals. I have checked them out on Evilbay and there are two kinds. One justs stirs and the other heats and stirs. Obviously the one that also heats would be great if you start with room temp distilled water, but I have a microwave oven heater for that.

I guess what I would like is your experience and the model that you use or recommend. I think that a 2lt capacity would be OK, but if it could handle a bucket that would allow a 1gal - 5ltr mix would be great too.

Thanks for any help you can give me in my decision.

 

[Lowly]

After having a problem with the time taken to mix the 5ltr packs I invested in a cheap non-heated magnetic stirrer from the auction site that could handle 5 litres. It's made life much easier! It would be nice to have a heated one but the stirrer's quite efficient so the solution doesn't lose too much heat while it's stirring. Definitely worth it to me.

 

[Robert Ley]

Who is the manufacturer of your 5ltr mixer and what is the model number?

 

[ann]

Have been using one for almost 30 years.

The chemistry teacher at a high school I taught for many years ago use to mix my chemistry for class and then when I moved I got one for myself, and that was in 1984

 

[mwdake]

I have a magnetic stirrer, no heater with it though.
I find it most useful for mixing hard to dissolve items like the potassium carbonate in Pyrocat HD.

 

[cmacd123]

They are hard to do without. The heater would be a nice touch, but I get along with a plain one. Don't forget to get some Teflon magnets.

 

[craigclu]

I'd sure promote it for you. I use a heated version and wouldn't be without the heater, personally. Resist the urge to over-speed the magnet as it will cavitate air into the mixture. Just keeping things in motion is sufficient. With heavier loaded powder like Na2SO4, it could require a little manipulating of your mix container around the spin point of the magnet to get the corner material moving but a bit of patience helps (and it sure beats hand mixing!).

 

[Gerald C Koch]

Have used the same one for 40 years. I find it indispensable. Beats elbow grease.

 

[heterolysis]

I use a hot plate with a magnetic stirrer. Works great for C-41 chemicals, even up to 5L, though the beaker takes forever to heat.

 

[Ken Nadvornick]

I use this Corning PC-420D hotplate/stirrer kit* and would never go back to manual mixing. In fact, after having carefully watched liquids of differing densities being mixed in a beaker by this unit, I quickly came to realize just how poorly I had been doing it by hand. It takes more effort and quite a bit longer than one might think.

I also found it to be much more efficient to purchase and use an inexpensive kitchen hot plate and water bath to initially raise the temperature of bulk liquids to at or near the desired temperature, then transfer over to the Corning unit for temperature maintenance and stirring. It's a two-step process, but greatly speeds things up.

Ken

* I got it new, but didn't pay anywhere near that MSRP price!

 

[artonpaper]

I have a stirrer with a heater. It works great for most things. I got extra magnets and a wand for retrieving them from the graduate from Edmund Scientific. The only thing it doesn't do well is stir and dissolve ferric oxalate. Heating it to around 150º and putting a top on the bottle and shaking the heck out it for about 20 minutes is the only thing that works for me.

 

[StoneNYC]

Can someone tell me what this is used for? Like, why is it magnetic? And what's it for? I've never had to "stir" before I just pour the chemicals in water, close the container, rotate it a few times and the working solution is ready to go... So ... I don't get it....


~Stone | Sent w/ iPhone using Tapatalk

 

[Ken Nadvornick]

It's used for mixing solids into liquids, or liquids into liquids.

It's magnetic because the mixing is accomplished by placing the container to be mixed on top of a plate that covers a rotating magnet. A small magnetic mixing bar is then dropped into the container. When the mixer is activated the bar is twirled by the rotating magnet below the plate, thus mixing the container's contents.

Fancier mixers also include a heating element below the plate so one can simultaneously heat and mix solutions. Many dry chemicals dissolve quicker and easier in warmer water.

Ken

 

[StoneNYC]

It's used for mixing solids into liquids, or liquids into liquids.

It's magnetic because the mixing is accomplished by placing the container to be mixed on top of a plate that covers a rotating magnet. A small magnetic mixing bar is then dropped into the container. When the mixer is activated the bar is twirled by the rotating magnet below the plate, thus mixing the container's contents.

Fancier mixers also include a heating element below the plate so one can simultaneously heat and mix solutions. Many dry chemicals dissolve quicker and easier in warmer water.

Ken

Oh, I've never had anything that needed a stirrer, but just bought my first bulk chemistry for mixing my own so maybe I'll have to get one...


~Stone | Sent w/ iPhone using Tapatalk

 

[Mike Wilde]

I don't recall the model number - it is years old and was bought for a good price used. Basic variac for speed control. You need to manually adjust the speed depending on if you have dumped in too much dry chemistry at once so the stirrier bogs down. Too fast, and it whips air into the solution, which is a nono for developers.

I added a heater salvaged from Bunn commercial coffee warmer to the underside of the stirring platform. It works best to hold temperatures, rather than actually heating the solution in any reasonable rate. Usually I mix in a 3.8L stainless steel beaker, or a 2L pyrex beaker or erlenmeyer flask if the solution needs to stay hot and mix for a long time.

 

[Jim Noel]

I would hate to be without a heated one.

 

[Robert Ley]

I have gotten a lot of good information here. I have another question. I plan on using a 1000ml and 2000ml glass beakers to mix my chemistry. What size mixing bar works best relative to size and shape?

 

[edcculus]

Hey guys, just saw this. I've never used one for mixing photography or lab chemicals, but magnetic stirrers are a big thing in Homebrewing for making yeast starters. Basically, the stirrer constantly aerates the yeast starter so you have a large initial pitch into the unfermented beer.


There are a lot people who have started making magnetic stirrers because the lab grade ones are either too expensive or too hard to find for the average homebrewer. Most that I know of are not heated. If you are looking for a good (cheap) stirrer homebrew yeast stirrers are a great place to start.

I have one from Stir Starters. It works great for my purposes. I use a 2000mL erlenmeyer flask for making starters with this device. I think he also has instructions on a DIY version on the website as well.

 

[StoneNYC]

I'm not sure how specifically a yeast stirrer differs from a lab stirrer in design, but aeration is definitely NOT what you want when mixing photochemistry.

Also I wouldn't use the stirrer in my yeast after using it in my chemistry... Haha


~Stone | Sent w/ iPhone using Tapatalk

 

[edcculus]

I'm not sure about design either. The speed is variable though, so if you were getting it to mix chemicals, you would just use a lower speed. For a yeast starter, you essentially want to get it going as fast as you can without throwing the bar. They also use the exact same teflon coated stir bars. I think the idea behind them is more economical than anything specifically designed for making a yeast starter. Afterall, there are plenty of homebrewers out there using lab stir plates too.

Just thought this might be a good option as they are always available, and you don't have to hunt one down on Evilbay.

 

[edcculus]

Also I wouldn't use the stirrer in my yeast after using it in my chemistry... Haha


~Stone | Sent w/ iPhone using Tapatalk

haha, yea, I'd make sure to use separate stir bars and beakers!

 

[WHof]

I got a Hanna HI 190M from American Science & Surplus in Chicago. It is certainly a hobby version but for about $40 it does the job. I did find, however, that a 1.5" stir bar works more efficiently than the 1" bar that comes with the unit.

 

[eclarke]

Have a nice, bought new, Corning hotplate stirrer. Best darkroom kit I ever bought.

 

[gleaf]

Bought a 9 x 9 inch, three torque setting, variable speed magnetic from the evil auction place. Seller was a reconditioned lab equipment house. Very pleased. Made sure I bought a serious sized magnetic cross shape stir bar. If you go industrial size make sure you check the speed setting before doing th Off to ON transition. Mine can spin up water right up the sides. Over kill but works wonderfully.

 

[heterolysis]

I'm not sure how specifically a yeast stirrer differs from a lab stirrer in design, but aeration is definitely NOT what you want when mixing photochemistry.

They appear similar in design, but from what I know about working with yeast, you're probably stirring for far longer than the 5min necessary to have your chemicals ready.