Diffusion of fluid through a semipermeable membrane from a solution with a low solute concentration to a solution with a higher solute concentration until there is an equal solute concentration on both sides of the membrane.
What has this got to do with fishing? It’s the simple process of curing single salmon eggs. There are allot of recipes out there and many individual are confident that they work.
The most natural way to toughen up a salmon single eggs is to obtain them from a ripe hen( female ), store them in a bag with river water and mix it with some milt from the male. Once the eggs have been fertilized the membrane will change. You literally can throw those eggs against a wall and watch them bounce. They will collapse if you puncture them but for handling and making roe bags this is natures best recipe. This opportunity doesn’t present itself often.
Next option if a male is not available is to store the single eggs in river water. I always carry a large zip lock with me for these purposes. Then cure them at home.
Another source of single eggs is to remove them from a skein that is close to separating. This is a process that will test your patience. With the skein up and eggs down on a smooth surface. I like to use parchment paper. You gently use a spoon on the edge of the skein and draw forward and pull the eggs off the skein. I then soak them in river water, which I have bought home for an hour. You will find the eggs soft and also partially collapse but not punctured.
Still another option is to purchase salmon roe. I got some VHS free Chinook single eggs from Centerpin angling and when they came they were in a vacuum-sealed bag. They choose to cure and somewhat dehydrate the egg during its process with added stickiness, soft form, and able to storage for years. Giving the customer’s the option, and when ready to use, to fish the eggs “as is”. Tying loose and naturally milking out scent and simultaneously naturally hydrate on the drift. Or even have the option to re-hydrate the eggs themselves with their own personal way, recipe, re-scent etc.(Not recommended)
With our big rivers on the west coast of British Columbia we like our single eggs for our roe sacs firm and bouncy as we cast hard and for long distances. If you want them to be firm this is when Osmosis will be your best friend.
Create brine that is at its maximum salinity. You want to see a 1/8 if an inch of salt still on the bottom of the jar. Gently place the singles eggs in the brine. They will separate if stuck together. This is when the magic begins. In the next 24 hours they will swell (rehydrate) and the membrane of the egg will toughen up. They will literally be able to bounce off the floor when the Osmosis process if over. I like to keep the process natural others like to add colour. I personally would rather change the colour of the netting.
Do not throw out the brine. When you have left over roe bags just put them back into the brine and back into the fridge. Remember oxygen is the enemy of eggs. So keeps the jar full of fluid and airtight. I have stored single eggs for years in an airtight canning jar removing as much air as you can.