Tips for laminating %100 sourdough to make croissants

If you are asking about the laminating part of making croissants, then the process is the same regardless of whether the dough (detrempe) is made with baker's yeast or is 100% naturally leavened with a levain/sourdough. You have to make sure the dough-butter layers are folded without the butter getting too soft, without tearing and without any other distortions in the layers. Just like with all laminated doughs, the number of layers you can optimally get depends on the folding combination you choose.

I make my croissants with a liquid sourdough pre ferment of 33% of the flour. However, I do add commercial yeast to the final dough.

When laminating, you would use the standard lock in and then 3 single folds. That's really all you need and about all you will be able to manage if you are doing hand lamination. Even if you have a sheeter, that's really all you need.

One of the essentials to good structure in the finished croissant is a thorough proof. Here's where 100% sourdough will be a bit of a challenge as the proof will take some time if only sourdough is used as the leavening. My croissants take about a 3 hour proof - at 78F - with commercial yeast added. Some bakers use osmotolerant yeast in croissants - as they do contain sugar. I have not found this to be required, but with only sourdough, you could be talking substantial proofing time. The shaped croissant should be very soft - almost "jiggly" and you will see the laminated layers quite clearly. Much less than this and you will get substantial butter leaking when they are baked.

Search on my user name to find my blogs. I have done some on regular croissants and some odd variations. (Just to illustrate that I am beginning to get the hang of this lamination stuff...)

Good luck.