Agar

[ATester]

Ok, here's a question for you flasking Joes (and Janes...never want to forget about those Janes!!!)

How long does it take the agar medium to set? I made mine up this morning and, though a little thicker, it still hasn't quite set.

Aaron

[muddhb]

I have had problems with this, but I think that I have finally solved my problem. The trick is that you need to get you media solution really hot (seriously...really hot, nearly boiling) before you autoclave or pressure cook it. I have been heating and stirring it until it is practically boiling, some say that you should not let it boil, I dont' know why though, and then I put it in the jars or containers and then autoclave them.

You would think that autoclaving for like 15 minutes at 120C would do the trick, but in my experience it for some reason doesn't always work, and more often then not fails for me. The last few times that I made media, I had some left over that I couldn't fit in the autoclave, so I put it in the microwave for like a minute. When I did that it did start to boil...but when it cooled down it was nice and firm and not contaminated.

That being said, the agar should set up when it returns to room temperature, and if it doesn't then no amount of time will help, you will unfortunately have to start over.

Ryan