Any solution with agar has to boil about a minute before you cool it.
If it's not totally melted it won't solidify. Be careful at this stage,
as it boils over and burns easily.
I've only ever used premixed plating media with agar already in it, but
it will turn clear when it's melted. Use padded gloves and keep
swirling it periodically while it's heating, unless you melt in an
autoclave. We used to make 2-3 liters at a time, so swirling this was
pretty tricky. If you're using smaller amounts use a large enough flask
(Ehrlenmeyers are great) so you can swirl, but not too big.
Judy Dilworth, M.T. (ASCP)
>> I am having trouble with my experiment (water analysis).
> The method just states "agar" as a solidifying agent and
> we bought Agar Grade A. Somehow, it won't set.
> The author of the method recommended Bacto Agar.
> Is there any difference between these two agars?
>> If there are so many solidifying agars (which are not selective) then how do
> you go about choosing the right one for your experiment?