Australia's Science Forum

So I've had a student that has been a bit airy fairy about how many agar plates she was going to need. I cooked up enough agar for an extra 20 plates. I didn't want to pour it because I suspected I would be wasting 20 petri dishes. So I sealed up the (Schott) bottle and put it in the fridge.
Of course, she now needs the extra 20 plates. I have a bottle of solid agar that I need to melt but I don't have a microwave. I've tried sitting it in a water bath, but ours only goes to 70 deg. I've tried sitting it in very hot water. I still have a mostly solid bottle of agar.

Any suggestions?

Could you use a staffroom microwave?
paper towel underneth, and power at 50%

I could wait until there's no teachers around! My agar is probably cleaner than what they've left behind in the fridge

Can you use a stirring rod to smoosh it up a bit? Do you have a magnetic stirrer hotplate? Maybe put it in a large beaker/small saucepan (if you have one) in a waterbath on that? Then once it's melted enough to transfer to a conical flask, pop the magnetic bean in and stir straight on the hotplate. Good luck!

place it back in the autoclave

So, the stage was set - all teachers were on class. I snuck in with my bottle, zapped it a few times for one minute on 50% and voila! I have liquid agar. I did have to air out the staffroom before they got back

Merilyn1 wrote: ↑07 May 2021, 12:09 So, the stage was set - all teachers were on class. I snuck in with my bottle, zapped it a few times for one minute on 50% and voila! I have liquid agar. I did have to air out the staffroom before they got back

Great!!! I'm glad it worked out for you! haha they'll never know!

hahaha wonderful!

Great you got it sorted..... I would have put it back in the autoclave if you have one.

I was really trying to avoid the whole process of cranking up the autoclave. Microwave worked a treat. No one noticed the smell...