Sciencemadness Discussion Board

Mantle or hotplace & stirrer for first heating device?

Thanatops1s - 9-8-2013 at 16:49

I'm in the process of building up a lab and was wondering what people think would be better for a first purchase? I was originally going to get a mantle for distillation but then thought that a hot plate would be a better option since I could use a water/oil/sand bath for round bottom flasks, plus I have the flat surface. I figure for first equipment, versatility is more important, especially when on a limited budget. There was a Thermolyne Cimarec 2 I was thinking of picking up. Any opinions on that model?

Metacelsus - 9-8-2013 at 17:37

A hotplate with a built-in magnetic stirrer is pricey, but nice to have. I recently got one after the insulation on my cheap, crappy "electric stove" type hotplate cracked and it started electrocuting me. However, if you're on a budget, I would recommend a cheap one, like what I used to have, from Target or whatever store sells them. They go as low as $12.99:
http://www.target.com/p/kitchen-selectives-single-burner-sb1...

I would definitely recommend a hotplate over a mantle; as you said, you can always use a bath.

Lambda-Eyde - 9-8-2013 at 17:40

Definitely go for a hotplate stirrer; they can be used with beakers, erlenmeyers as well as various heating baths for accomodating RBFs and oddly-shaped containers. Heating mantles are a luxury and something you should only consider when you have a better equipped lab and feel that you use RBFs often enough to justify it. The stirring feature is also something that will make your life much more pleasant. (I find it kind of ironic that I own 6 heating mantles and a magnetic stirrer without heating - haven't found the money to buy a hotplate stirrer yet)

I can't vouch for that particular make or model, but Corning and IKA make great stirrer hot plates. To afford them on a mortal's budget you'll have to buy on the used market. Steer away from the Chinese stuff on eBay.

Thanatops1s - 9-8-2013 at 17:49

Quote: Originally posted by Cheddite Cheese  
A hotplate with a built-in magnetic stirrer is pricey, but nice to have. I recently got one after the insulation on my cheap, crappy "electric stove" type hotplate cracked and it started electrocuting me. However, if you're on a budget, I would recommend a cheap one, like what I used to have, from Target or whatever store sells them. They go as low as $12.99:
http://www.target.com/p/kitchen-selectives-single-burner-sb1...

I would definitely recommend a hotplate over a mantle; as you said, you can always use a bath.


I'm not sure what you mean by pricy, but my budget is $100 or so. If you mean some of the high end ones brand new, yeah I can't believe how much some are. But there's two in particular of the same model on ebay now that end tomorrow and the current high bid is $100 so I think I'm leaning towards one of those.

I've seen some videos on Youtube of people using a round bottom flask directly on a hot plate, is it just me or is that just asking to create a serious hot spot and break your flask?


[Edited on 10-8-2013 by Thanatops1s]

ElectroWin - 9-8-2013 at 17:52

when heating stuff for chemistry it is really desirable to be able to regulate temperature to within narrow ranges; so hot-plate with sensor and closed-loop control goes a long way.

i am lusting for an annealing oven, for doing ceramics work, that lets me program in a sequence of target temperatures and soak-times

Lambda-Eyde - 9-8-2013 at 18:06

Quote: Originally posted by Thanatops1s  

I've seen some videos on Youtube of people using a round bottom flask directly on a hot plate, is it just me or is that just asking to create a serious hot spot and break your flask?

Unless we're talking very high temperatures I think that's highly unlikely. I've done it myself for my larger flasks for which I've not had a suitable mantle, together with a "skirt" of aluminium foil to reduce convection.

The only problem with that technique I'd say is that you're not heating the contents uniformly and that it wastes time and electricity, which can be alleviated to an extent with the foil skirt.

Edit: also, it is harder to maintain accurate and stable temperatures without a bath.

[Edited on 10-8-2013 by Lambda-Eyde]

smaerd - 9-8-2013 at 18:43

I chose a heating mantel and a stir plate. I never regretted it. I mostly have an interest in organic chemistry though so for the year or so I went without a hot-plate I had plenty of fun with round bottoms and room temperature/ice-bathed erlenmeyers.

Depends on what you're interested in I guess.

Thanatops1s - 9-8-2013 at 18:48

Quote: Originally posted by smaerd  
Depends on what you're interested in I guess.


Well I'm pretty much a beginner. I've been reading about chemistry for years and am just recently getting into actually doing things instead of just reading about them. So I guess right at this moment versatility is my main goal. Looks like the hot plate/stirrer is the way to go.

Acidum - 10-8-2013 at 03:20

Mostly we used heating mantle for distillations of greater amounts of organic solvents (1-5 l), and hotplate magnetic stirrer for everything else, from reactions to distillations of lesser amounts of chemicals. Versatility of hotplate magnetic stirrer is just unsurpassed... We mostly used IKA, excellent quality indeed.

That is on faculty, at home I can only dream about those... But if I had a choice, first hotplate stirrer, then mantle for larger batch productions...

Thanatops1s - 10-8-2013 at 07:59

http://www.ebay.com/itm/Thermolyne-Ceramic-2-Hotplate-Stirre...

So I decided on the hot place/stirrer, just won that. A Thermolyne Cimarec 2 for $102.50. There were a lot of pretty beat up ones on there around the same price, this one looks to be in pretty good condition. It was either not used a ton, or taken good care of.

Thanatops1s - 13-8-2013 at 08:25

Just got it from Fedex this morning. This thing really is in excellent condition and seems very well made. I think I made the right purchase.



[Edited on 13-8-2013 by Thanatops1s]

Blue Matter - 13-8-2013 at 09:35

I have a hotplate stirrer, a normal hot plate, and a mantle I use my normal hotplate for messy reactions that might spill the hotplate stirrer I only use on certain occasions when things need stirring and heating, but by far my favorite one is my electrothermal electromantle I got off eBay it heats up very fast and precisely imho I think hot plate is best for a while but eventually you should get a heating mantle

MichiganMadScientist - 13-8-2013 at 10:20

I see that you have already made your purchase, and I too, have a high opinion of Thermolyne stirrer/hotplates. Most of mine are made by Corning or those (Talboys), but I'm conviced that Corning is putting a rather weak magnet on its stirrers these days.

Thanatops1s - 14-8-2013 at 13:00

Quote: Originally posted by Blue Matter  
I think hot plate is best for a while but eventually you should get a heating mantle


I definitely plan to in the future. However seeing as I'm just starting to build up my lab and am on a limited budget, versatility was my main goal here. Now once my ring stands and clamps come in, I can do my first distillation. For the first one, I'm just doing to use salt water(figure I might as well do something nice and safe first) but then it's going to be some nitric acid.

Blue Matter - 14-8-2013 at 16:27

Its fun distilling alcohols and seeing how close to pure you can get them by calculating density and then comparing to concentration charts that's what I did when I got my setup.

jamit - 14-8-2013 at 16:42

Quote: Originally posted by Thanatops1s  
Just got it from Fedex this morning. This thing really is in excellent condition and seems very well made. I think I made the right purchase.



[Edited on 13-8-2013 by Thanatops1s]


Thermolyne is a good choice for hotplate stirrer. I have at one time or another owned all the brand names of hotplate/stirrer and the one that is the best is Corning... any of the PC-351, 320, 420 and 420D and even 620/D are all excellent choice. I also have VWR and Thermolyne and the newer models are good but the older model is just "so-so".

As for heating mantles... I also own like 5 different sizes and types from Glas-col and Electromantle. But unless you are into organic chemistry... heating mantles are not as important as a good and reliable hotplate stirrer. Ebay is the best place to get these items.

[Edited on 15-8-2013 by jamit]

ChemSwede - 24-9-2013 at 09:56

Hello.
I'm currently looking for a magnetic stirrer. My budget is set to around 200 EUR.
The cheapest ones are the chinese stirrers on Ebay, but I've heard that they can malfunction quite often.
I would prefer one from Europe.

I've found this seller on Ebay, from the UK:
http://viewitem.eim.ebay.se/-NEW-MAGNETIC-HOTPLATE-STIRRER--...
It's from Maple Scientific. Seems good, but has anyone hade any experience with them?
They also have a homepage: http://www.maplescientific.co.uk/

Any other advice about where to get a good and not too pricey stirrer w hotplate would be appreciated.

[Edited on 24-9-2013 by ChemSwede]

Variscite - 24-9-2013 at 14:01

Ive had my eye on the pc-351 for a little while and I wish to get it, the only problem ive heard is that it simply doesnt put out enough wattage to heat larger volumes of liquids efficiently(500 mL+). Does anyone have any input on this?

MichiganMadScientist - 24-9-2013 at 20:20

Quote: Originally posted by Variscite  
Ive had my eye on the pc-351 for a little while and I wish to get it, the only problem ive heard is that it simply doesnt put out enough wattage to heat larger volumes of liquids efficiently(500 mL+). Does anyone have any input on this?


Kind of an old thread, but I'll stick my two cents in....

Any of the Corning brand PC-series hotplate stirrers should be more than sufficient in terms of hearing. I've never had any problems with any of mine. If anything, my complaint is with the magnetic stirrer. For some reason the magnet on some of Corning's models are weak and fail to hold on to a Stir bar at high rpms. But again this is just my personal experience. Corning still makes a top notch product...

You can always try wrapping the the hotplate and beaker with aluminum foil to trap heat around the beaker. But again, I personally doubt that you'll even need to resort to this...

ChemSwede - 18-10-2013 at 06:52

I decided to buy the stirrer/hotplate from Maplescientific. I got it a bit cheaper after mailing with the seller, and it's in the EU, so no customs fee.
It's chinese made, but so far no problems. Heating and stirring works fine.

Dr.Bob - 18-10-2013 at 12:34

Quote: Originally posted by Thanatops1s  

I've seen some videos on Youtube of people using a round bottom flask directly on a hot plate, is it just me or is that just asking to create a serious hot spot and break your flask?


I will add my $0.02 here. I would never use a hotplate to directly heat a rbf. Depending on the brand, size and type of flask, there is a good chance of breaking the flask, bumping of the solvent, or other issues. There cannot be good thermal transfer with only one point of contact.

I will use them for heating water in a beaker or erlenmeyer flask, but only slowly and gently. And any highly flammable solvent is best heated by water or oil bath (heating a pan of water/oil and then using that to heat the flask). That works fine for smaller rbfs. For larger ones (~1L and above), that can be harder, that is where a heating mantle starts to make sense.

elementcollector1 - 18-10-2013 at 14:17

Personally, I prefer a sand bath - it's easy to set up, non-flammable, and heats flasks very evenly.

Mailinmypocket - 18-10-2013 at 14:27

If you use a coiled element hotplate sandbaths are great. Maybe it's my usual bad luck, but once I was heating a sand bath on a ceramic top hotplate and it burnt out. I'm not sure if sand baths retain too much heat and screw up the thermostats or something, or it might be bad luck. I wouldn't do that again though, personally. What a piss of that was!

Lambda-Eyde - 18-10-2013 at 17:38

Quote: Originally posted by Mailinmypocket  
If you use a coiled element hotplate sandbaths are great. Maybe it's my usual bad luck, but once I was heating a sand bath on a ceramic top hotplate and it burnt out. I'm not sure if sand baths retain too much heat and screw up the thermostats or something, or it might be bad luck. I wouldn't do that again though, personally. What a piss of that was!

Sand is an excellent insulator, that's why. I only use sand for very high temperatures (>200 degrees). Below that I go for a heating bath or a mantle.

Silicone oil is the ideal choice for a heating bath where water can't be used. Inert, non-flammable and very heat stable. You can get it for around 20$ a liter on eBay. Expensive, but well worth the investment considering two liters should last indefinitely.