We recommend the following to prepare an agarose gel:
Weigh out the desired amount of agarose and place it in an Erlenmeyer flask with a measured amount of electrophoresis buffer. Make sure to use the same electrophoresis buffer in the gel as for the running buffer.
Example: For a 0.8% gel, add 0.8 g of agarose and 100 mL of TBE Buffer (1X), to a 200 mL flask. The larger flask insures against the agarose boiling over.
Dissolve the agarose in a boiling water bath or in a revolving-plate microwave oven. All the grains of agarose should be dissolved, and the solution should be clear.
Cool the solution to 60°C (70°C for concentrations 2% or above) and pour immediately.