Sciencemadness Discussion Board

Magnetic stirrer/hotplate

brew - 16-5-2008 at 18:58

I need one; have not the time to learn and then try to build one. Currently a student, hence looking for a good second hand one that is not too expensive. I've thought of ebay, LabX but thought I would check out in this forum that perhaps someone here might be able to help or direct me to a good buy perhaps.;)

bmc

ADP - 17-5-2008 at 20:31

I looked today because I am going to buy one as well. Best bet is a used one on ebay unless you want to spend at least $100 for a new one. They can certainly come in handy

chemrox - 17-5-2008 at 21:31

you need at least one good one.. keep watching ebay until there's one that wasn't listed in the right location and hasn't attracted notice .. may take awhile .. or bite the bullet and pay ther freight at ebay .. they're popular.

brew - 18-5-2008 at 06:40

Yes, if I am going to get one, I want one that will reach a high temperature and is not poorly made. Labx appears good and is an auction purely for lab items within the industry.
I used an oil bath on electric stove at late for distillation and it was a pain in the a$$ to control temp and I suppose practise makes perfect but it was a nightmare.

bio2 - 18-5-2008 at 10:23

Put the heating element in the oil controlled by a dimmer.

Easy temp control and way less heat input required.

brew - 18-5-2008 at 18:13

I will have a look at purchasing/finding an element with a controller/dimmer.
Thanks.


bmc

VTchem - 18-5-2008 at 18:39

Did you buy your oil or did you use vegetable oil or what, like most of you guys, I am trying to do this on the cheap and am not sure what to use as my oil bath, I have heard things like sunflower or canola oil works but what do you guys use?

ShadowWarrior4444 - 18-5-2008 at 19:03

Quote:
Originally posted by VTchem
Did you buy your oil or did you use vegetable oil or what, like most of you guys, I am trying to do this on the cheap and am not sure what to use as my oil bath, I have heard things like sunflower or canola oil works but what do you guys use?


Not to be too cutting, but there is a thread on oil bath oil in this form a few spaces beneath this one:
http://www.sciencemadness.org/talk/viewthread.php?tid=10535

Cursory overview: Mineral oil from the pharmacy laxative section is quite useful.

brew - 19-5-2008 at 00:50

I have used parrafin wax, bought as a solid at RT and I have also used canola which has been stated and discussed on other posts - as this has been noted etc

I found the parrafin wax/candle wax without any additives(i think) is the best, but pending your source can be expensive. Id doesn't appear to fume at higher temperatures. Canola oil at a higher temperature smells like a Fishandchip shop. It apparently is full of long chained saturated fats via synthetic routes thus calling them trans fatty acids. They are not so reactive hence a longer shelf life which sort of hints at their possible negative effect at a physiological level. If you can smell the fuc---- theyre possible able to f--- with you!

I have not tried mineral oil but it has been suggested by numerous forum users.

bmc

ADP - 19-5-2008 at 05:10

I personally am looking to buy a magnetic stirrer without the hotplate feature, I've already got one and don't foresee needing both at the same time...

-jeffB - 19-5-2008 at 10:01

Quote:
Originally posted by brew
Canola oil at a higher temperature smells like a Fishandchip shop. It apparently is full of long chained saturated fats via synthetic routes thus calling them trans fatty acids. They are not so reactive hence a longer shelf life which sort of hints at their possible negative effect at a physiological level. If you can smell the fuc---- theyre possible able to f--- with you!


Not to threadjack, but I hate seeing this kind of FUD about canola. Canola oil does NOT contain significant trans fats, nor is it "synthetic", nor is it high in saturated fats. For that matter, saturated fats can't be trans-fats, because the cis- vs. trans- distinction can only arise across a double (i.e. "unsaturated") bond.

Canola is high in healthy monounsaturated fats, low in saturated fat, and cheap. Since it's high in unsaturated components, it does not have a "longer shelf life". Keep it tightly sealed when you aren't using it, and it's a lot better for you than butter, margarine, or motor oil. For oil baths, though, it's probably not the best choice. Use paraffin, or mineral oil, or Crisco.

brew - 19-5-2008 at 15:20

I obviously need to of refered to a reliable source of the chemical composition of Canola oil in order to determine the amount of saturated fats and unsaturated fats. My understanding of trans fats are that they are usually syntheticaly produced when the double bond is hydrogenated( perhaps partialy) thus maintaining some unsaturated fatty acids(or unsaturated bonds remaining) of the Canola oil. I was not stating that the oil itself is syntheticaly produced. This process I believe is done in order to increase shelf life. Also my perhaps not so thorough look at canola oil indicated a high degree of medium to long chained fats. I also know that there is alot of Hype concerning Canola oil due to its GM status. I need to be more careful in my use of language and perhaps include references when I comment about a product such as Canola oil.

-jeffB - 19-5-2008 at 15:46

Quote:
Originally posted by brew
I obviously need to of refered to a reliable source of the chemical composition of Canola oil in order to determine the amount of saturated fats and unsaturated fats.


Tread carefully when you do. There are a lot of people who have convinced themselves that canola is some sort of evil elixir of doom, and they claim that the Governmental-Industrial-Agricultural Complex is falsely claiming that it's safe.
Quote:
My understanding of trans fats are that they are usually syntheticaly produced when the double bond is hydrogenated( perhaps partialy) thus maintaining some unsaturated fatty acids(or unsaturated bonds remaining) of the Canola oil.


Yes, approximately. Double bonds can't be "partially" hydrogenated; they either are (becoming single bonds) or they aren't. "Partially hydrogenated oil" is polyunsaturated oil (oil starting with multiple double bonds) that has some, but not all, of its double bonds hydrogenated.

I confess that I don't know how hydrogenation flips the orientation of some remaining double bonds, but that's apparently what happens.
Quote:
I was not stating that the oil itself is syntheticaly produced. This process I believe is done in order to increase shelf life.


I'm quite sure that someone somewhere has an application for hydrogenated canola oil. But the stuff that's sold in supermarkets, and the stuff that's listed as an ingredient in more and more processed foods, is not hydrogenated.
Quote:
Also my perhaps not so thorough look at canola oil indicated a high degree of medium to long chained fats.


That may well be true. I haven't yet been paying attention to the short-medium-long-chain issue.
Quote:
I also know that there is alot of Hype concerning Canola oil due to its GM status.


And, as (1) a technology enthusiast and (2) an American, I'm doubly isolated from anti-GM hype. :)
Quote:
I need to be more careful in my use of language and perhaps include references when I comment about a product such as Canola oil.


If nothing else, it'll embarrass those of us (like me) who are lax about including such references.

Seriously, though, read with a critical eye. There is a lot of anti-canola information out there that appears, to me at least, to play fast and loose with the facts.

brew - 20-5-2008 at 01:17

I understand that a double bond is either reduced-added hydrogen to it- or not, and that this cannot be partially done. I heard that the process of making trans fats is that they somehow add hydrogen to the fatty acids whilst still maintaning some, or at least one double bond. ( hence my use of the word partial) I am assuming, or perhaps have read, that the motive for industry to do this, is to still claim a product being unsaturated whilst increasing its shelf life. I think that for me to comment about an oil as controversial as Canola oil is, as is the case in Australia, then it is perhaps a bit foolish for me not to back up what I am stating.
And yes I will tread carefully, or at least try to when I do back up my comments with references as such.

bmc

brew - 21-5-2008 at 15:28

Quote:
Originally posted by ADP
I personally am looking to buy a magnetic stirrer without the hotplate feature, I've already got one and don't foresee needing both at the same time...


Various reactions may require heat and stirring, more so than the turbulence produced with heat alone. You may not need it now, but later on it could be useful!
I am also keeping my eyes open for a mechanical stirrer as sometimes low temp conditions are needed that also require stirring. I am sure there are cheap drill type motors that I could attach a glass rod or some sort of plastic rod with attatchment to stir etc. I will search the forum as I am sure this would of been explored.

bmc

ADP - 27-5-2008 at 15:31

Well here is my new baby, I'll have to just do without the heat, brew

kalacrow - 27-5-2008 at 18:25

What is it's heat tolerance?

PS: Wait a sec.. that's from American Science and Surplus!
It's a 190M series and is not rated for heat at all, unfortunately. However you can rig it with heat protection with some SS sheet.

[Edited on 27-5-2008 by kalacrow]

[Edited on 27-5-2008 by kalacrow]

brew - 27-5-2008 at 23:49

Looks pretty spic ADP. I am sure you have considered the option I presented and decided appropiately etc.
I'll have to sort something out my self. Perhaps I will check out this Science and surplus store myself.

bmc

ADP - 31-5-2008 at 08:29

Yes all of the applications that I can foresee won't use heat, however I do see how it could be useful in the future, but at half the price it was hard to say no to. I've never heard of Am. Sci and Surplus but that's a pretty cool site, I got mine one ebay for about $20 cheaper.

BTW what is SS sheet kalacrow?

undead_alchemist - 31-5-2008 at 23:39

SS = stainless steel

Hamyrenz - 9-12-2009 at 18:16

I absolutely agree based on my experience just keep watching on Ebay. I also spend my time searching for new items in Ebay. You can easily see if the items that you need out of stocks.


_________________
Deep Fryer

grndpndr - 15-12-2009 at 09:57

Ive seen new low end hotplate-stirrers for $20 more than
Sci-surplus is selling the stirrer for.4.5x4.5 plate suggested 500ml 1600 RPM? only rated to 100c however.SH2, $114+ s-h. I wouldnt be suprisedd if there are better deals out there but e-bay bidding seems to get out of hand for an unknown?Persistent and lucky for a deal on ebay.As was mentioned they are popular items.