How to make salted egg? Easy! Just follow the procedures here and going wrong is unlikely.
How to make second batch of salted eggs? Read the first paragraph. You have made the first batch. Making the second batch would be easier. You’re definitely an expert making third and more batches.
I mean discard the clay mixture or brine solution after each production. It can be reused for the second time, third, and so on but the resulting eggs get less and less salty each time.
Osmosis takes place once the eggs are soaked in clay. Salts travel through egg shell thus lowering the mixture salt concentration. If the same salt mixture is used for the second time, less salts are expected to participate in osmosis.
What a waste! Reuse the first salt mixture for the second time. The following may help you get more or less accurate result:
1) Use the sharp senses and excellent brain memory. Prepare the brine. Get a portion and store in clean sterilized jar. Get another portion at end of process and compare its taste against stored brine. Compensate by adding salt gradually.
May not be applicable to clay method. Maybe if …
2) Do the MATH. Analyze the salt mixture before and after. As in analyze quantitatively using salinometer. Compute for necessary adjustment.
3) Lazy hydrometer method. Place the hydrometer on prepared solution. Mark the reading. Place it again after processing. Add salt to attain the previous reading. For brine only.
4) Use a specific number of eggs and egg size per given volume of salt mixture for the purpose of establishing time frames. Smaller eggs get saltier faster. More eggs mean more salt loss from clay or brine medium. Inconsistencies result to quality deviation.