Once both sets of dough have fermented for at least 6 hours, it's time to form the doughs into 2 marbled bread loaves. This recipe will also make one larger loaf that will fit into a roughly 9" - 10" round pan.
Uncover the sourdough white loaf bowl and empty the dough onto a clean, flat surface that has been oiled or patted down with water to prevent the dough from sticking.
Flatten the white dough into a rectangle, or split the dough in half to press out two rectangles.
Repeat these steps with the dark rye dough.
The following process is the same whether you have two rectangles of dough or four. Layer the dark rye on top of the white dough and slightly press the layers together. Be gentle.This will result in the white dough being baked up on top. You may also reverse this, if you want the dark rye to end up on top of the finished bread. If you have four rectangles of dough, continue stacking until all the dough has been piled together. Gently press each layer. Gently.
Starting from the longest edge of the rectangle, carefully begin to roll up the dough into one, long log. Tease the dough off the surface of the counter carefully, if it wants to stick. Wet or oil your hands if necessary. You may also use a pastry scraper to scrape the backside of the dough as your roll.
Stopping about halfway through rolling, fold the corner edges of the dough into the center to tuck them in. Finish rolling to the end and smooth the dough to flatten the seam.
Use a sharp knife or a pastry cutter to cut the dough in half, if baking in sandwich pans. Place one dough log in each pan and cover to rise.
If using loaf pans, grease two more loaf pans on the inside and invert them over the rising dough. This will keep the dough damp and warm as it rises. It will also keep out bugs and debris. Allow the dough to rise until roughly doubled in height. This can take 1-2 hours, or more. Be patient; rye flour is less inclined to rise quickly than wheat flour.
Allow the dough to rise until roughly doubled in height. This can take 1-2 hours, or more. Be patient; rye flour is less inclined to rise quickly than wheat flour.
Remove the inverted bread pans to cut slashes in the top of your dough. I use scissors, but you may also use a razor blade. Return the inverted pans over the bread dough.
Place in a cold oven and set it to 425F/218C. Bake for 35 minutes covered.
Remove the inverted bread pans and reduce the temperature to 400F/204C. Place a piece of foil over the baking bread if the crust begins to brown to quickly. A sourdough bread loaf is fully baked once it reaches between 200F - 205F (93C - 96C).
Remove from the oven and turn out onto a baker's rack to fully cool. This can take upwards of 24 hours. If you cut into the bread while still hot, you may flatten the loaf and turn the crumb a bit gummy.