Magnetic Stirrer. Straight, or One With Heating to a Specific Temperature Feature?

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Mick Fagan

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I last used a magnetic stirrer around 30 years ago, it was an industrial model capable of handling 20 litres of solution; there was another stirrer which I never got to use which handled up to 500ml. Back then the cost of magnetic stirrers in this country was prohibitive, now it seems as though every person needs a magnetic stirrer for all sorts of things, including cooking food; which I find a fascinating development of this probably once pure scientific tool.

I would like something that can handle up to 2.5 litres of solution, which is when I mix chemistry for paper developer. Looking around the web at Australian based suppliers, there seems to be a plethora of units with varying degrees of doodads which, within reason, seem surplus to my requirements, or maybe not.

The main extra seems to be one with heating capability, which invariably has a temperature sensor held by a swinging frame into your solution. Photographically speaking I pretty much use 50ºC as my starting temperature using the inbuilt temperature monitor (Tel-Tru) on my darkroom over the sink water pipe. Fill whatever container I'm using to approximately 65% of the intended maximum and start from there. I have a standby jug of water with the same temperature with which I rinse my containers out after depositing dry chemistry into the solution; placing that rinse into the solution.

My 3 litre glass mixing container calibrated to 2500ml, is pretty much what I use for paper developer and such, it has a base of 115mm diameter and would work perfectly with this unit. For film developers I work from 500ml through to around 2000ml with three sizes of containers. These days I'm mixing chemistry close to once a week, mainly film developer, and although I don't mind spending 30 minutes or so getting all chemistry into solution using a Paterson hand mixer (on my third one in 40 years), I could be doing something else in the darkroom while the chemistry was being mixed into solution.


On the other hand spending a bit more, adds a heating element into the unit as well as temperature monitor and so on. My question here is this:- is having a heating possibility by those who have that possibility useful, or something you don't use much, if at all?


Last but not least, is having different sized stirring bars a requirement, bearing in mind my differing solution capacities being stirred? Or is a bigger one in small solutions running slower, just as good as a small one going like the clappers? Perhaps there is a stirring bar size to revolution ratio formula, which indicates which size range of stirring bar is better suited to a certain range of solution size? Thinking of vortex size here.
 

koraks

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I went for low budget, so no heating. It's just fine 98% of the time. Most stuff dissolves at room temperature anyway, and if it needs to be warmer, I just start with hot water. Once in a blue moon I place a larger tub with hot water on the stirrer with the vessel inside of it (bain marie) if it needs to remain warm for a longer period of time. But that's probably once a year, if that.

I also have just one bar, the one that came with the stirrer. Never found myself in need of another one.

I do admit I mostly mix small volumes, up to 500cc or thereabouts.
 

juan

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I’ve used an ordinary magnetic stirrer for about 20-years for all my water based chemistry. I’ve mixed everything from 500ml to 4L with the larger bars. Lately, I’ve been experimenting with glycol and TEA. The need for heating has me thinking about getting a new stirrer with that feature, especially the prices are more reasonable.
 

Peter Schrager

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go for one with a heating element and never look back
you can also look for sales of used lab equipment; I have an IKA and it's really well made
 

Alan9940

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I used a non-heating stirrer for years, but eventually bought a heating one specifically to mix 510-Pyro. I found that keeping the TEA at a constant warm temp really helped to properly mix the dry chemicals. Now I'm hooked on it for every formula I mix. I do use a couple of different lengths of the stirring rod, based on the size of the container.
 

Nodda Duma

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Go to amazon and search for ASIN# B073FLH5R9

This is the magnetic stirrer I use for making smaller batches of emulsion, handling the amount you’re interested in.

I also used B01IARARWU for larger batches.

I use these because you can set the temperature exactly. I need this for stringent temperature control..more stringent than what’s needed for mixing developing chems. The smaller will overshoot but then maintains the proper temp, but with use I learned how to adjust temp up to avoid overshooting. The larger has a PID controller to avoid overshoot but is more expensive. I have bought several of each and they have lasted through hard use for 4+ years.
 

RalphLambrecht

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I last used a magnetic stirrer around 30 years ago, it was an industrial model capable of handling 20 litres of solution; there was another stirrer which I never got to use which handled up to 500ml. Back then the cost of magnetic stirrers in this country was prohibitive, now it seems as though every person needs a magnetic stirrer for all sorts of things, including cooking food; which I find a fascinating development of this probably once pure scientific tool.

I would like something that can handle up to 2.5 litres of solution, which is when I mix chemistry for paper developer. Looking around the web at Australian based suppliers, there seems to be a plethora of units with varying degrees of doodads which, within reason, seem surplus to my requirements, or maybe not.

The main extra seems to be one with heating capability, which invariably has a temperature sensor held by a swinging frame into your solution. Photographically speaking I pretty much use 50ºC as my starting temperature using the inbuilt temperature monitor (Tel-Tru) on my darkroom over the sink water pipe. Fill whatever container I'm using to approximately 65% of the intended maximum and start from there. I have a standby jug of water with the same temperature with which I rinse my containers out after depositing dry chemistry into the solution; placing that rinse into the solution.

My 3 litre glass mixing container calibrated to 2500ml, is pretty much what I use for paper developer and such, it has a base of 115mm diameter and would work perfectly with this unit. For film developers I work from 500ml through to around 2000ml with three sizes of containers. These days I'm mixing chemistry close to once a week, mainly film developer, and although I don't mind spending 30 minutes or so getting all chemistry into solution using a Paterson hand mixer (on my third one in 40 years), I could be doing something else in the darkroom while the chemistry was being mixed into solution.


On the other hand spending a bit more, adds a heating element into the unit as well as temperature monitor and so on. My question here is this:- is having a heating possibility by those who have that possibility useful, or something you don't use much, if at all?


Last but not least, is having different sized stirring bars a requirement, bearing in mind my differing solution capacities being stirred? Or is a bigger one in small solutions running slower, just as good as a small one going like the clappers? Perhaps there is a stirring bar size to revolution ratio formula, which indicates which size range of stirring bar is better suited to a certain range of solution size? Thinking of vortex size here.

You can certainly turn this into a yet uncharted science, requiring a a four-year degree to mix chemicals.
 

BobUK

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I eventually upgraded to a heated stirrer when I started making 510 PYRO.

The Triethanolamine (TEA) used in 510 Pyro needs to be raised to 80c according to the instructions that I follow.
 
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Mick Fagan

Mick Fagan

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Koraks, interesting information and pretty much why I asked the question about heating or non heating.

Juan, I'm where you are with regard to heating, except I don't have a stirrer of any kind, yet.

Peter Schrager, I looked at the IKA range and the cheapest one in Australia starts at $763.51 AUD plus tax, which doesn't include a temperature sensor. From then on all of their equipment says: Ask for Price, which usually means it won't be cheap. Bit over my pay scale, but I see where you are coming from.

Alan 9940 your description is pushing me further towards a heating magnetic stirrer.......

Nodda Duma, I checked both of those out, pretty much where I'm at and as for the temperature overshooting, yep, once one has zeroed the temperature knob in, things should be alright. That larger one looks great. Landed in Australia, the cheaper one is around $150 AUD, the tyranny of distance from a big market like mainland USA.

Ralph, I like your sense of humour, one could almost see a doctorate happening if one delved far enough into it.

Bob UK, now that is interesting, I've never done Pyro and now that I know one requires 80ºC or thereabouts, that could be the clincher. Probably never do Pyro, but one should never say never, eh!

Now to do some homework on what kind, what size, with what functions.

I'll get back to you on what I decide, meanwhile it is a perfect summer's day, and the rooftop solar is running riot so I can hit the darkroom with the air conditioning on for free, and be a cool cat while I develop some film... Life is so hard being retired.
 

koraks

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The Triethanolamine (TEA) used in 510 Pyro needs to be raised to 80c according to the instructions that I follow.

510 pyro is one of the mixes that I use a tempering bath for. Since I rarely mix it, I just accept the minor inconvenience of bringing some water to the boil when I make this recipe.

Having said that, when I bought my stirrer, the heated ones weren't as cheaply available as they are today. I think given the choice today, I'd just get a cheap/simple one with a heater for convenience's sake.
 

RalphLambrecht

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Koraks, interesting information and pretty much why I asked the question about heating or non heating.

Juan, I'm where you are with regard to heating, except I don't have a stirrer of any kind, yet.

Peter Schrager, I looked at the IKA range and the cheapest one in Australia starts at $763.51 AUD plus tax, which doesn't include a temperature sensor. From then on all of their equipment says: Ask for Price, which usually means it won't be cheap. Bit over my pay scale, but I see where you are coming from.

Alan 9940 your description is pushing me further towards a heating magnetic stirrer.......

Nodda Duma, I checked both of those out, pretty much where I'm at and as for the temperature overshooting, yep, once one has zeroed the temperature knob in, things should be alright. That larger one looks great. Landed in Australia, the cheaper one is around $150 AUD, the tyranny of distance from a big market like mainland USA.

Ralph, I like your sense of humour, one could almost see a doctorate happening if one delved far enough into it.

Bob UK, now that is interesting, I've never done Pyro and now that I know one requires 80ºC or thereabouts, that could be the clincher. Probably never do Pyro, but one should never say never, eh!

Now to do some homework on what kind, what size, with what functions.

I'll get back to you on what I decide, meanwhile it is a perfect summer's day, and the rooftop solar is running riot so I can hit the darkroom with the air conditioning on for free, and be a cool cat while I develop some film... Life is so hard being retired.

You are correct, prices in AUS are beyond reasonable, but, it has always been more expensive to live on an island, even if it is a big island.
 

BobUK

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510 pyro is one of the mixes that I use a tempering bath for. Since I rarely mix it, I just accept the minor inconvenience of bringing some water to the boil when I make this recipe.

Having said that, when I bought my stirrer, the heated ones weren't as cheaply available as they are today. I think given the choice today, I'd just get a cheap/simple one with a heater for convenience's sake.
Koraks , I also used a water bath at first for heating my 510 Pyro but, lots of steam was swirling around the tops of the beakers that I was using. It may be a bit over the top but, I wondered about water vapour getting into the developer and reducing it's shelf life. I now use a sand bath. It is just an old metal pie dish pinched from the kitchen, with an inch of sand in it and the pyrex beaker nestled down into the hot sand.
If my theory is not correct, at least I have peace of mind about the water content of my Pyro.
☂️
 

koraks

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Since pure TEA is a soild at room temperature and my TEA sure enough is a syrupy liquid, I assume it has some water in it anyway, so I don't worry too much about a few milligrams of steam added to the mix :smile:
 

Vaughn

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Koraks , I also used a water bath at first for heating my 510 Pyro but, lots of steam was swirling around the tops of the beakers that I was using. ...

Since I keep liquids at temperature for long periods of time in a tempering bath, I put a lid on the container to keep water from evaporating from the container. More worries about water leaving that taking it in.
 

BobUK

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Since I keep liquids at temperature for long periods of time in a tempering bath, I put a lid on the container to keep water from evaporating from the container. More worries about water leaving that taking it in.
Vaughn I never thought about that that way.

I think you must be a glass is half full, and I am the glass is half empty type of person. 😀
 
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Mick Fagan

Mick Fagan

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Well a decision was made, I went with one that had heating capability along with enough power to induce a vortex in 2000ml of solution. As the final product is 2500ml this will be adjusted too, after all solids are in solution.

This is what I bought and interestingly once I decided upon the choice, I found the direct website, (or at least I think the direct website) of the supplier. Once there, the price drop from eee-bay was between $20-$25 lower, which probably reflects the margin the host of the site takes.

$149.99 AUD delivered to my door is the deal I have. Now I'm eagerly awaiting its delivery.


Many thanks to all of your responses, quite educational.

Ralph, I agree with you, Australia is quite an expensive place to live but living on an Island Continent does have some advantages. Hopefully on our next trip, the one way distance to our major destination is around 5,500 klm, taking us through sand deserts, stone deserts, monsoonal wetlands and other interesting geological marvels. All of this while staying in the one country; bliss.

Just don't mention the flies, mosquitoes, crocodiles, snakes. Herds of feral wild camels in arid/desert areas, feral water buffalo in wet areas, pythons and (usually) tree snakes in shower/toilet blocks, Death Adders are another step up though:- https://untamedscience.com/biodiversity/death-adder/

Mick.
 

Bill Burk

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Search for this: You hook it up to a hose and put your pot on top of it… water drive. It’s so small and simple and reliable. Plus there’s no shock hazard.

GFS Chemicals

Turbine-Driven Stirrer​

 
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Mick Fagan

Mick Fagan

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Bill, I must admit this is something completely new to me, never knew something like that existed.

However apart from the base price, and forgetting delivery charges to Australia with taxes on top of everything, it is $371.46 AUD and that's just the starting price.

Missing is important information with regard to water kPa requirements for any given speed, not to mention the amount of water required to either be pumped, requiring electricity somewhere, or a total loss system using water from a tap in the darkroom.

Very interesting idea though.
 

mshchem

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I found a Troemner Talboys model 101, shaft drive variable speed mixer, never used, on fleabay several years back. Really kicks as☆. I can mix up 5 L of XTOL in a couple minutes, doesn't aerate the water, a few quick bursts suspends all the sulfite and other goodies.
I worked in an analytical lab doing bench wet chemistry magnetic stirrers work great if you don't overload. Having a built in hot plate is handy, sometimes the hot plate requires moving the drive magnet so far away that it loses hold of the driven magnet when put under a load. I've seen good and bad.
 
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Mick Fagan

Mick Fagan

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Now an afterthought with regard to using the magnetic stirrer that I've just ordered, versus using heated water from my inbuilt darkroom 31.5 litre stainless steel lined HWS to make photographic solutions.

The hot water system, which I purchased second-hand around 33-34 years ago has been wonderful, but with a 3000W element it certainly sucks power. To that end I mostly switch it on when the sun is shining and we have excess rooftop solar generation, this is a bit problematic in winter for obvious reasons. Even with 20 kWh of usable energy from house batteries, that darkroom HWS just sucks power.

The magnetic stirrer that I've ordered has a 500W heating element, and a few Watts of extra power to turn the magnet and run the display. This is a huge reduction in power draw and another very small win for the planet.
 
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Mick Fagan

Mick Fagan

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Having a built in hot plate is handy, sometimes the hot plate requires moving the drive magnet so far away that it loses hold of the driven magnet when put under a load. I've seen good and bad.

Something else I've learnt from this thread; I'll let you know how it goes.

Presumably the force required to properly stir various amounts of liquid is why various models have varying ability. I hadn't thought that it was the magnetic attraction losing attraction, if that is the correct understanding of what you are saying, being the cause.
 

eli griggs

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I've been using a simple design for my stir plate, based on beer makers homemade stir unit, easily seen on YouTube.

Build a four sided box/frame with about four or five inch wide boards; hardwood cabinet plywood is fine.

Mount a thin bottom board/ply sheet to the bottom, with good air holes positioned on the four bottom corners, plus a side positioned hole for an electric phone charger cord, which will connect to your stir motor, which will be a 12 volt DC computer fan, sized for your boxes space.

Hardmount or hot glue the fan motor to the center of the bottom sheet, with the fan blade side closest to the top or face of the box, no yet installed.

Use strong, rare earth magnets, 3/4" (18mm) or 1" (25mm) oriented in the same upward direction when stacked, and hot glue, clean oil free magnets to clean, oil free blades.

You might be able to attach two @ large disk magnets to your fan blades, so try and see what's possible before a final glueing up.

Wire the fan to an ordinary cell phone charger, and mark your disk magnets's edge position by plugging in your outlet plug, and using a thin paint brush with acrylic paint, by lowering the loaded brush, slowly into the path of the spinning blades, where you want to place magnets.

This way, you'll be able to evenly space your disk magnets and achieve some ballance to the finished device.

Use a 6mm sheet of Plexi or Lucite, pre-cut and pre-drilled to span to the edges of your box to it's edges.

You can use hot glue or better yet, silicon calk on top of the box top's wooden edges to prevent liquids from getting underneath the clear plastic top, with small, counter-sunk bugle head wood screws.

You can install a "speed control" between the power unit and outside of the box, but however you use it, buy/make an assortment of coated stir-bars, small medium, large.

Good luck.
 
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gordrob

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Just don't mention the flies, mosquitoes, crocodiles, snakes. Herds of feral wild camels in arid/desert areas, feral water buffalo in wet areas, pythons and (usually) tree snakes in shower/toilet blocks, Death Adders are another step up though:- https://untamedscience.com/biodiversity/death-adder/

Mick.
Thanks for the link Mick. I think that I will take Australia off my travel bucket list.🙂 I am used to living in an area where our biggest threat is a Black Widow spider or a bear and not much in between. In fact we do not even allow rats in our province, We do have rattlesnakes 100 miles east of here on the prairies but that is about it. But I am still a big fan of Aussie Gold and seeing just what the outback is all about.
Gord
 

Bill Burk

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I have one of these water turbine stirrers and its speed varies with the amount of water you run.

I haven’t measured how much water it takes but it’s reasonable. A rubber surgical hose fits and can take the necessary pressure.

I have seen them closer to $30 USD, it looks like today is just a bad day to try to buy one. Keep an eye out.
 
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A lot of people seem to be happy with models from that maker in the emulsion making communities - I hope it will work well!

I'd just make sure to check the electricals to make sure there are no problems since there seems to have been some problems at times.
 
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