Recommendations for stirrer / hot plate units?

Discussion in 'Darkroom Equipment' started by Jeff Bannow, Jan 5, 2011.

  1. Jeff Bannow

    Jeff Bannow Member

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    I've looked at some of the used hot plate / magnetic stirrer units on eBay, but I'm kinda overwhelmed by all the choices, and also what options and features I'm looking for.

    Anyone here an expert on these things? Can you recommend a unit that is on the cheaper side of things? I would like to spend under $100.
     
  2. Neal

    Neal Subscriber

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    Dear Jeff,

    I have a NuovaII by Thermolyne. It doesn't have a heater and I doubt you will need one unless you need to control the temperature over a long period of time. The supporting surface is 7"x7" and I use a 2-1/2 gallon plastic pail for all my mixing. I'm confident that a mixer with a smaller support surface would work as long as I added outside support for the mixing container so even a relatively small (and usually cheaper) stirrer will work for you. I'll bet you can get away with less than $30 without a heater.

    I only mix Dektol, Xtol and Kodak HCA, but it is really convenient to turn it on low and walk away. Order a stirring bar at the same time as most on ebay don't have them included.

    Neal Wydra
     
  3. Mike Wilde

    Mike Wilde Member

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    One the cheap side, I have made a DIY approach.

    I think my basic stirrer, at least 40 years old, and found used in the basement of my favourite photo dealer for something like $40 a few years ago, would be a good start.

    I then picked up a commercial Bunn type coffee warmer used at the thrift store, and took the 300W nichrome heater core in sleeve, and the bracket used to originally hold it to the underside of the carafe area, and transferred them to the underside of the top plate of my stirrer. It does not interfere with the spinning magnets.

    I independently control temperature by on time of the heater by using an old refrigeration controller with the NO contact used instead of NC side of the control relay that uses a thermocouple as its sensor. The sensor geta taped to the side of the 4l stainless vessel I use when mixing heated chems. The power side of the heater is fed by a solid state relay.

    I have also used left over refective bubble wrap around the sides of the vessel, and a piece of rigid foam insulation over the top to keep heat in if it is a long stir.

    It is not pretty, but the price is right, since everything in this set up apart from the stirrer came used over time for either as thrift or garage sale purchases.
     
  4. Dinesh

    Dinesh Subscriber

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    Mike, you truly are MacGyver.
     
  5. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    The one I have came from the lab in a closed-down county hospital. New it would be $500, surplus it was part of a large box of laboratory junque that I bought for $5. Someone got in ahead of me and bought all the analytical balances. I should have bought the waterbaths - they regulate to 37C/98.6F.

    I would search ebay and be on the lookout for closings at hospitals, clinics and laboratories. I just looked at ebay - lots of fairy-tale pricing going on. If you look at completed items you can see many sold for $30 - $80.

    I am thinking of putting together and selling a combination PID temperature controller and stirring paddle that could be used with any electric skillet, slow cooker or othersuch appliance for either waterbath or mixing operations.
     
  6. Dan Henderson

    Dan Henderson Member

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    Jeff, I bought a little Hanna HI 190 M magnetic stirrer online, from an Amazon reseller I believe. I see they are selling for around $75 right now. It is not heated but that has not been an issue for me. I just heat the water up in my darkroom microwave before mixing in chemicals. Now that I have begun mixing as many of my solutions as practical, you would have to bring a very large stick to take it away from me.
     
  7. Jeff Bannow

    Jeff Bannow Member

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    Thanks for the recommendations all. Maybe I don't need a heater after all?

    Hmm ... I suppose I could make one with an old car engine and some duct tape ....
     
  8. TheFlyingCamera

    TheFlyingCamera Membership Council Council

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    I don't remember where it was that I saw it, (might have been here) but if you really want to do the combination heating/stirring thing, go steampunk and adapt a steam-powered record turntable - the piston on the steam engine can run the stirrer and the steam/exhaust from the boiler can be vented into a tube that encircles your vessel.
     
  9. Jeff Bannow

    Jeff Bannow Member

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    Now that would be awesome!
     
  10. JohnMilleker

    JohnMilleker Member

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    I purchased the Corning PC-420 stirrer/hot plate. At first I wasn't going to go for a Hot Plate model and I'm glad I did. Most chemicals want to be stirred in warm/hot water. Since I use bottled distilled water it would be just one more step in heating it or microwaving it.

    They can get expensive for a good lab rated model but they're worth it. As already mentioned you add water, chemicals a bit at a time and walk away. And to think, I used to slave over stirring and stirring and stirring the mix in a graduate.

    You will need the magnetic stirrer bars (Mine came with one that looked like a football, I purchased new ones that look like more of an elongated pill) and I recommend a nice glass Pyrex beaker. I have one that is 800ml, I really need to get a 1L model.
     
  11. eclarke

    eclarke Member

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    I have a Corning 620D/heated which I bought brand new an it's one of the top ten best photo things I own. I make developer 4 liters at a time and this thing makes it a real snap. They come up used quite a bit but I was at the lab supply one day and saw it sitting there, had the money in my pocket and went impulse, glad I did.
     
  12. Lee L

    Lee L Member

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    The electronics tech for the local college here buys Corning stirring hotplates on ebay and refurbs them to supply the chemistry dept. When I asked a few years ago he was paying about $40 for them in decent condition and fixing any problems himself. If they paid him only what he's saved them over the years he'd be a millionaire. I have been meaning to, but haven't yet asked him to snag a unit and check it for me.

    Lee
     
  13. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    Just looked on Amazon - lots of really cheap stirrers available. Even the name brand heated ones are selling for less than an acid-spill Corning is going for on ebay. China supplying the methlab market?
     
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  15. eclarke

    eclarke Member

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    I like my Corning because I am a production kind of person when in a working environment. A nice Walmart alternative is to buy a single burner electric hotplate and a cheap immersion/stick blender. It only requires you to stand and hold the blender but it mixes quickly. I will grab my stick blender if I have a stubborn clump of chemical in my Corning, sometimes the stir bar won't break them up fast but the stick will break them instantly...EC
     
  16. Jeff Bannow

    Jeff Bannow Member

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    Stick blender - now that's an interesting idea ...
     
  17. eclarke

    eclarke Member

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    And it works:smile:
     
  18. MattKing

    MattKing Subscriber

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  19. Jeff Bannow

    Jeff Bannow Member

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  20. greybeard

    greybeard Member

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    A factoid that may possibly be of interest: a magnetic stirrer can be used to make a hole in the bottom of a stainless steel developing tank.

    I once had to mix a batch of Polaroid 55 clearing solution, which is essentially water saturated with sodium sulfite. The sulfite that I had was lumpy, so I put it and the water into a tank with a teflon-coated stirring bar, sealed the top with Parafilm, and let it sit overnight. The next morning the solution was clear, and there was a brightly polished dimple where the ridge at the center of the stirring bar had been sitting.

    Either the teflon was glass-reinforced (which I think is the most likely answer) or the stainless was depassivated at the point of contact and fretting corrosion produced the dimple.

    Fortunately, it didn't go all the way through.....
     
  21. photoncatcher

    photoncatcher Member

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    I guess I'm just a low tech kind of guy. I use an old nylon spoon that my dad, and I used since the early sixties. I don't even need to plug it in.
     
  22. michaelbsc

    michaelbsc Member

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    Wasn't someone around here singing the praises of that thing for an E6 tempered bath a few months ago?
     
  23. MattKing

    MattKing Subscriber

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    I think it was me - but it was the same sort of "I wonder if this would work" post.
     
  24. holmburgers

    holmburgers Member

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    Is any magnetic stirrer & hot plate going to reliably keep ≈115° and hold it while stirring. What's the usual range?

    I'm starting to get the itch for one of these after some rather cumbersome nights over the kitchen stove with a thermometer and spoon (not fun).

    edit: I should mention that I'm mixing carbon-glob and other gelatinous things. Is the high viscoscity going to be a problem?
     
  25. VaryaV

    VaryaV Member

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    I have an old Corning heated stir plate I got from the Parasit lab and I wouldn't part with it for the world. It's a gem for mixing powdered chemicals. I just set the amber gallon glass jug on top of the heated plate, drop in the magnetic stirrer and it dissolves very quickly. I went berserk trying to dissolve powders with a spoon. Not sure how high the temp goes. Tried to boil water on it to cook spaghetti and it didn't quite come to a rolling boil...:D
     
  26. traveller

    traveller Member

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    As you work with higher viscosities I would recommend you a hot plate stirrer with digital control (the stirring function can be useful for other applications) and a overhead stirrer. Magnetic stirrers get used with low viscosities and if your temperature range is +/-1° this will work.

    As Corning gets recommended so often (I prefer IKA :whistling:) here is a link to the technical data

    BTW, don't get shocked when you see the list prices for new equipment..