Paper thin crust
How to get a thicker more stout crust?
I have been making bread for about a year now after getting into it after receiving the Tartine book a couple Christmases ago. I initially started out with a few goes at the natural leaven loaf in the book but after killing my starter a too times I altered my process and have been using packaged yeast for the time being. Even though I am not working with wild yeast (which I would prefer to) I am learning a lot and making some really tasty bread. I am very happy with the taste, look, and smell of the bread but am disappointed by the structure of the crust. The crust in some places feels as thin as paper and when I cut it the loaf will not hold shape. My ideal outcome for this bread would be to keep everything the same just with a thicker more stout crust.
3g active dry yeast
I start the poolish in the morning and let it sit for three hours. When ready I dissolve what I can in 700g of water then add 1000g flour, mix and let sit for 20 to 30 min. Next I add the salt and the remaining 50g water. I stretch and fold every 30 min or so for about 4 hours. I shape the loafs and put them in bowls lined with a towel that has a 50/50 rice/wheat flour mixture on them. Depending on how late in the day it is and what I have the next day I might bake the loafs anywhere from 4 to 24 hours later (any longer than 4 I put them in the fridge). I bake them in a cast iron pot that is cool when I put the loafs in with the oven pre heated to 475. I leave the lid on for 25 min and when I take it off I turn the heat down to 450 and bake for another 20 min. Initially the crust is very hard and sounds great if you squeeze it but after 20 min out of the oven it becomes very soft. Once the loafs cool to room temp they regain some rigidity but for the mast part it stays soft.
I can say that when I was first making loafs with the natural leaven the crust was closer to what I would like. Does the type of leaven used make a difference in how the crust comes out?
Any ideas on how to get a more desirable crust would be greatly appreciated.