Glass rod puzzle

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MariaC
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Glass rod puzzle

Post by MariaC » 15 Dec 2008, 13:49

:-( Im just about going stir crazy!!!Ive been trying to fire polish glass rods for about a week now! It does not matter which type of burner, how long or where I put it in the flame they will not go red and melt!! Do they make glass rods out of borosilicate glass :? I just found some rods and cut them up I wondering if they could be the wrong glass, everyone says how easy it is but I am having no fun at all :cry2: Any ideas???thanks

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Robb
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Re: Glass rod puzzle

Post by Robb » 15 Dec 2008, 15:08

Hi Maria C,

All types of glass that we are subject to in Science will melt even the Borosilicate type is heated strongly and long enough.

To fire polish (without tating the obvious) will need the burner on the Blue flame and approx 2cm from the inner lightblue cooler cone. This will give you good results. Also gently turn the glass rod/tubing to ensure uniform polishing.

Cheers,

Robb.....
Dr Robert Crosdale. MRACI. NSS. NSSA. NASA.
Ph.D (Chem), Post Grad Ph.D (Physics), M.Ed, B.Sc (Hons), Dip. Appl. Sc. (Chem)
Lake Munmorah High School.
University of New England.
University of New South Wales.
University of Newcastle.

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cheltie
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Re: Glass rod puzzle

Post by cheltie » 16 Dec 2008, 09:02

Hi Maria,
I have also had this problem.
The last school I was at I had no problems making the stirring rods with the glass that was there.
When I came to this school there was already some long glass rod and I tried to melt it to make stirring rods with no success.
One of the teachers tried to show me what I was doing wrong and also had no success.
Gave up and bought some plastic stirring rods. Much less hassle.
Helen

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Voice
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Re: Glass rod puzzle

Post by Voice » 16 Dec 2008, 09:09

I must admit I bought the plastic stirring rods about 3 years ago and have not looked back. There are only 2 problems.
1. Students might burn them.
2. Students have cut the ends off.
However, they don't break in the students' hands creating danger and of the 40 I bought 3 years ago, I still have 40.
They are a great way to go.
Maree

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Ocker
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Re: Glass rod puzzle

Post by Ocker » 16 Dec 2008, 11:16

I like the plastic ones too
I have a similar problem Natural gas is not as hot as LPG and only just gets hot enough to melt thin glass, when it's thick not enough heat!

MariaC
Posts: 174
Joined: 29 Oct 2008, 12:34
School: Central Coast Grammar School
Suburb: Erina Heights
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Re: Glass rod puzzle

Post by MariaC » 16 Dec 2008, 14:08

:wink2: Maybe thats my problem too, they will soften abit but not enough to be a blob at the bottom, only enough to get rid of sharp edges. Will follow up my gas supply, I have noticed I cant get a nice strong blue flame, lots of orange happening.Thanks for the help.

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Lyn
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Re: Glass rod puzzle

Post by Lyn » 16 Dec 2008, 14:24

`You need a batwing bunsen for melting glass rod or for doing any work with glass tubing. They have no collar and the diameter at the top is about 25mm with lots of fine holes. The flame is very low, burns blue and is very hot. Glass gets red hot. Just checked the Livingstone school catalogue and under bunsen burners they have a Meker bunsen burner 28mm. This could possibly be the same as what I call a batwing burner but they don't show a picture of it. See if they can fax you an image of that bunsen. The price is certainly on the large size.
Lyn.

MariaC
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Re: Glass rod puzzle

Post by MariaC » 17 Dec 2008, 07:42

Thanks Lyn but thats what ive been using, I tried an ordinary bunsen too! Thats why I couldnt understand what I was doing wrong but as suggested I think it may be the gas :thumbup: Thanks for helping

bigmack
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Re: Glass rod puzzle

Post by bigmack » 03 Jul 2019, 12:31

Here's my Puzzling question about the strirring rod.

At a recent PL day while stirring a solution with a glass stirring rod I mentioned how the noise of the Yr12 Chem class had almost driven me batty last week .......tinkle ,tinkle, tinkle...... :crazy:

Then a couple of Labbies looked at me puzzled and told me I was using it wrong and that the rubber bit ( which I always thought was the handle ) was meant to go into the solution to stop the tinkling .

Now I would have though this was a potential cross-contamination point as they are often cracked / burned etc and hard to clean .
The class seemed mixed opinion wise as to how they should be used .

Thoughts .
Stiring rods.jpg
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remlap12
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Re: Glass rod puzzle

Post by remlap12 » 03 Jul 2019, 14:11

Mine don't even have rubber ends, just glass!!
Regards
remlap12
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Labbie
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Re: Glass rod puzzle

Post by Labbie » 03 Jul 2019, 17:20

We have rubber ends, and after washing we put them rubber ends only into a milton solution, never had a problem. By using the rubber ends to mix with, does save the glass beakers. The clear plastic did last longer then the rubber ones.
Regards Labbie

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Now retired :wub:

Prima
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Re: Glass rod puzzle

Post by Prima » 04 Jul 2019, 13:47

I was laughed at when I put the rubber end in the solution - that's apparently the bit that you are meant to hold! Don't have many left now, replacing them slowly with the white stirring rods, I think they're great.

bigmack
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Re: Glass rod puzzle

Post by bigmack » 04 Jul 2019, 13:58

Thanks for the responses .....interesting . It would seem that its common to do it both ways, each has a valid reason .

I asked my Chem teacher what he does . He said he gets the juniors to use the rubber/plastic end in solution to save wear on the beakers but says the seniors use that end as a handle as he recons there is cross contamination possibility .......not a big deal for junior classes but something he likes to make the seniors aware of .

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