Australia's Science Forum

Hi All,

Just wondering how many people have microwave ovens in the prep room?

What type of things do you use them for?

Thanks
Lorrae

Hi Lorrae,
Just bought one. I use mine to make the agar for agar plates, because I hate pressure cookers, and the microwave recipe I use is simple, and works well. I used to borrow one from the staffroom when I needed it (they have two), but the teachers kept complaining they had to queue for the remaining microwave (poor dears!). But it gave me enough of an excuse to get my own!
Cheers,
Lisa

WE do not have a microwave oven in our prep room. I also hate pressure cookers. So do not sterlize my agar plates.

I also have to sterillize my plates in pressure cooker(and hate it). I wish I had a microwave.
Lada

We have a microwave in our prep room and we use it for a few things -
such as Agar plates and melting chocolate for chocolate fossils. I would recomend one for any Science department. Also they are good for a hot chocolate on a cold morning .

We have a microwave in the science staffroom for edible stuff ( though I seriously doubt that description of some of the food I see being put into it) and another one in the science prep room for doing agar, making plastic, dying wool ( my hobby and seeing I don't have a spare microwave at home I bring my stuff to school) making playdough etc.

Both are rather old models and you have to sit by them and count off the time but they do the job.

Definately a good addition to a prep room

Wendy

My prep room is adjacent to the Science Staff room where the teachers have their lunches. The Microwave is in the staff room.
We use the microwave for making lunch! We melt chocolate for chocolate fossils. I make my Agar in the pressure cooker, but store it in conical flasks, which I melt in the microwave (the agar, not the flask!). I sterilise the pipettes, etc from StreamWatch as they do not fit in the pressure cooker. The staff do not seem to mind me melting the agar etc in the lunch MW as they figure that it is probably more sterile than some of their lunches any way. The MW is cleaned each week by the staff member on"Cleaning Sink" duty, otherwise I would not trust my sterile agar to it!

Ian

I have a microwave oven in my prep room. I use it for agar plates, electrophoresis buffers, heating up water sometimes... heating up your lunch. You can use it for lots of things. I find it very handy.

Cheers

I use my microwave for heating hydrogen peroxide, to demonstrate the effect of heat on rates of reactions; making playdough; heating agar to make stupid agar tubes for the "surface area of cells" experiment; examining how much electricity it takes to heat up 500mL of water in a microwave compared to a electric kettle; heating marshmallows to make them grow; and BEST of all the electric grape experiment, which is the hugest laugh.

The HNIC (Head Nun in Charge) didn't think Science Dept ought to have one, but I accidentally bought one during the last week of school last year, with my budget surplus, and forgot to mention it to her!

Interestingly, I went to a microbiology workshop recently, where I was assured emphatically that microwaves do not sterilise agar, and do not not not sterilise cultures of germies either! Very disappointing, as I too HATE the pressure cooker, not least because the rubbers perish up here and they're so hard to get replacements for!

Cheers, K

Mine is a very old one (doesn't even have a turntable) and I use it for making playdough, heating up water (a lot quicker than the hotplate or bunsen burner) and have even used it for defrosting rats! No one ever wants to heat their lunch up in it when I tell them what it's been used for.

Now, that IS interesting about Microwaves not sterilising germs. My wife used the microwave to sterilise our babies bottles, and I am sure that the StreamWatch girl told me to sterilise pipettes in the Microwave. 10 minutes with half a cup of water. I wet the pipettes and wrap them in Glad Wrap. I guess it is the steam that does the sterilising.

regards
Ian

We have been thinking of purchasing a Microwave for the prep room. But on reading that they do not sterlize agar plates. Has any one else heard this one??????????

Hi all

Surely if there is water present and you heat it hot enough for a long enough period of time your agar is sterilised or the steam sterilises your glassware? I have not had a problem with agar in the microwave. Pressure cookers went out with the ark.

Julie

Hi everyone
A question on the agar plates and microwaves- do you put the used agar plates back in the microwave to destroy the "flora". We have only got one in the staff room and I did not want to use it with used agar plates (also worried it may not do the job?) so replaced old non-working pressure cooker with new one and it is great to use!
Regards
Sue

Yes I am sure they suggested useing Oven bags, tie the agar plates up, so their is no mess. And put them into the Microwave, but I am unsure how long for.

We are still using a pressure cooker in our lab (and will be for quite some time!!!!) and yes they can be rather scary!! I usually use a small piece of Autoclave Indicator tape (indicating line changes to black after sterilization) if I have been successful! Maybe you could use the indicator tape in the microwave?? Maybe you already do that??? Just a suggestion! Cheers. Judy

To Fibreweb and Smiley, please could you pass on your method for making plastic in the microwave, and what is the electric grape experiment? Also for playdough, do you put all ingredients in a bowl and then cook, for how many minutes?
Thankyou Rosalie

Electric Grape Experiment : This is a lunchtime "I am looking for ways to liven up the staffroom" type of thing, but here goes.

Get some healthy looking grapes, seedless if possible. Cut grape almost in half across the perpendicular, so that you end up with two little half egg shapes, with a little hinge of grape skin still joining the halves. Place these joined halves on a micro-proof plate in the centre of the microwave. Put the microwave on high for about 30 seconds. This will be too long, so be prepared to press stop when the reaction occurs. Press "Start".

Grapes will go round and round, while you count Mississippi's - as in "one Mississippi, two Mississippi" for general effect. Somewhere between the 9 to 15 mark, electric sparks will arc across the little flap of skin, and it may even have little flames to match . On a good day the two halves will actually blow apart. Laugh like a maniac, until you suddenly find yourself explaining to the HNIC why there is an electrical storm occuring in the microwave. This then becomes justification for buying your own microwave for the prep room, where you can be crazy in private - more or less.

I have yet to discover why the grape skin sparks, and you may have to have a couple of goes, as sometimes the grapes themselves just boil on the inside and explode with no fun sparks at all - self-extinguishing really. Still, its good for a laugh on a slow day, in a Mythbusters kind of way.

Cheers, K

Here's the recipe I use for playdough:

2 cups plain flour
1 Tbsp veg. oil
1 cup salt
4 Tbsp cream of tartar
2 cups warm water


Mix everything well together in a 4L ice cream container. Microwave on medium for 6 minutes, stirring every 2 mins.
Cooked when leaves the side of the bowl.

Makes 1kg.

Really though, any playdough recipe should work for you.

I find it can be very hard to stir if making a larger amount. Don't despair if it seems to be cooking faster on the 'outside' - it will mix together OK, and then really come together as you knead the colour in. I do this at the end (wearing gloves), so that I have several different colours on hand at any time, and then store it in the freezer in sandwich bag sized balls.

Have fun!

I tried a grape in the microwave and didn't have time to talk about rivers before there were flames and sparks. Quite surprising and impressive. Thanks
Rosalie