Glossary
Windowpane test
Stretching a small piece of dough thin enough to see light through it, a check on whether gluten development is far enough along.
The windowpane test checks how developed a dough's gluten network is by pulling a small piece of it thin between the fingers. If the piece can be stretched into a thin, translucent sheet without tearing, thin enough to see light or a shadow of your fingers through it, the gluten is considered well developed and ready for the next stage.
This test matters because gluten strength affects how well a dough will trap the gas produced during fermentation; dough that tears immediately when stretched usually needs more mixing, more folding, or more time to develop before it can hold a strong rise. It is commonly used after an autolyse and a few rounds of stretch and fold to check progress without over-handling the whole batch of dough.
No tools are needed for this test beyond clean, lightly wet or floured fingers to keep the dough from sticking as you pull it. A common mistake is testing a piece taken from the edge of the dough mass rather than the middle, which can give an inconsistent read since edges sometimes develop unevenly. Testing gently, and being willing to fold a few more times if the dough tears easily, avoids under-developing the final loaf.