Well, Denise, this thread was an adjunct to the dispersion making thread that I posted the same day, at least in part. The other thread demonstrates the use of homogenization or "blending".

No method should ever be used with emulsion crystal making that breaks up or changes the grain size by force, as this will fog the emulsion. This is destructive and uses a lot of energy which is expended on the emulsion in the form of shear and heat both. The method used must be mixing action that does not shear the emulsion and that does not allow gelatin or silver halide to accumulate on the bottom of the container. It must not whip air into the emulsion.

Basically then, to summarize, this thread was to point out that:

1. Up to about 500 ml, stirring at about 300 - 700 rpm will work well for most emulsion making.

2. Over 500 ml, you need a mixer running at that same speed or higher, but not high enough to cause air to be whipped into the emulsion.

3. Over 500 ml, you may need a mixer and a stirrer both to prevent gelatin from "burning" or just collecting at the bottom of your container, especially if you use a hot plate.

4. Over about 3L and with most modern emulsions at any scale, you need some sort of mixer running at up to 5000 rpm.

5. To make dispersions, you need a homogenizer.

6. Modern emulsions need a special sort of mixer that can act like a homogenizer but without cracking or shearing grains.

PE