Starting a sourdough culture on rye flour

The description and pictures below present how a sourdough culture was started on rye flour. On all days the environmental temperature was around 30 C. In case the temperature would have been lower, the below schedule would have slowed down. In such a case it can take more time before a fully active sourdough culture is achieved. Note that the rye flour was about 7 months beyond the "best before" date.

DayDescription
1 Mix 50 gram rye flour and about 75 gram of (bottled) water to form a thick paste. The paste is put in an airtight container and closed.

2 Observe bubbles in the paste. Open the container and admire the bubbles. Close the container.

3 Mix in enough bread flour to form a very stiff dough. Put in a cup and cover with clingfilm.

4 The dough has doubled in volume. It will not rise much further since the gluten structure has weakened and the dough can not retain the gasses.

From now on the sourdough culture is put on a double-double feeding scheme i.e. the amount of water is double the amount of sourdough culture, and the amount of bread flour is double the amount of water. This feeding is repeated everytime the dough has risen to its maximum volume. And the feeding is repeated until the dough triples/quadruples in about 6 to 8 hours.

Mix 25 gram of the sourdough culture with 50 grams of (bottled) water and 100 gram of bread flour. Put in a cup and cover with clingfilm.

After about 10 hours the dough has doubled in volume and does not increase in volume further.

Mix 25 gram of the sourdough culture with 50 grams of (bottled) water and 100 gram of bread flour. Put in a cup and cover with clingfilm.

5 In 8 hours the dough has about tripled in volume.

Mix 25 gram of the sourdough culture with 50 grams of (bottled) water and 100 gram of bread flour. Put in a cup and cover with clingfilm.

6 The dough has more than tripled in volume in 8 hours and does not increase in volume further.

Mix 25 gram of the sourdough culture with 50 grams of (bottled) water and 100 gram of bread flour. Put in a cup and cover with clingfilm.

The dough has more than tripled in volume in 6 hours and does not increase in volume further. The culture is now ready for usage and storage.

Once the sourdough culture triples/quadruples in 6-8 hours it is ready for use in breadmaking. In order to store the sourdough culture, it can be maintained as a stiff culture or as a liquid culture.

When the environmental temperature is much lower, the above schedule will slow down. It is possible to increase the speed by making the dough more liquid at every stage. Instead of using 25g, 50g and 100g for the sourdough culture, water and flour respectively, 25g, 75g and 75g can be used for the culture, water and flour respectively.
Additionally, it is possible to increase the inocculation further to e.g. 50-75g for the sourdough culture. Note that the sourdough needs to be monitored more closely as activity may drop more rapidly after its peak. Stiffer cultures are better buffered.