and some upgrades
i made some changes. i use chemical metal and sand it smooth.
I applaud your construction efforts.
An observation of your results......It looks like at least some of the gold in your pictures is greater in size than 30 to 50 mesh mixed with other stray particles much smaller in size. With less effort and time you could probably just pan for gold recovery some of the material if you were to classify first, and you may already be doing this to some extent. In fact if you felt it necessary to blue bowl some of the smaller mesh material, you would probably end up with cleaner results if you were to run each size fraction separately. My recommendation is to classify to these sizes: plus 30, 50, and plus and minus 100 mesh.* I think that is what the makers of the blue bowl recommend as well. When gold is about equal in size to other material in the pan it is relatively easy to separate out while panning. Each of the mesh sizes mentioned reduce particle size by about half. While panning small mesh sized material it is recommended to pan in small quantities and most usually do about a tablespoonful at a time.
Good luck in whatever you do.
* Inexpensive small classifiers (4-6") of these mesh sizes are available in the U.S. but may not be where you are. You may find it necessary to just obtain some screen material and make your own.
