As we learned earlier (daf 46), the custom today is to make sure that the entire process of baking matza takes less than 18 minutes from beginning to end. Nevertheless, in the time of the Mishna, dough was considered hametz when it showed certain signs of leavening.
The first Mishna on our daf teaches about the approved baking process. Rabban Gamliel rules that three women can prepare and bake simultaneously using one oven. The hakhamim say that all three must be involved in different baking activities in order to ensure that the dough does not become hametz – one kneads, one shapes and one bakes. Rabbi Akiva objects to the application of objective standards, arguing that we need to anticipate that the women will work at different speeds and that the fuel and ovens will be at different temperatures.
Some understand Rabban Gamliel’s ruling as stating that there is enough time to bake three rounds of matza before leavening takes place. Others argue that this would only be the case if the women are continuously kneading the dough throughout the baking process. The Rambam rules that in such a case, as long as the kneading continues, the dough will never become hametz, and Rabban Gamliel was giving an example, but, in fact, even more than three women could be involved in the baking simultaneously.
The second Mishna on our daf focuses on when dough is thought to have become hametz.
Dough at the beginning of the leavening process [siur], must be burned, but one who eats it is exempt from the punishment of karet because the dough had not become fully leavened. Dough that has reached the stage of cracking must be burned, and one who eats it intentionally is liable to receive karet, as he has intentionally eaten leavened bread during Passover.
According to Rabbi Yehuda, siur – the beginning of the leavening process, which is indicated by the dough turning a pale color and developing cracks – is not yet considered hametz, although it must be destroyed. Siduk – cracks appearing in the dough that intersect one another – is considered to have become hametz. Hakhamim rule that once any cracks appear, the dough has become hametz, and eating it on Pesaḥ would make one liable for karet (excision).
The Mishna describes the cracks under discussion as ki-karnei hagavim – like the antennae of locusts. The comparison between the cracks on the dough and the antennae appears to refer to both the shape of the antennae and their size – about 12-15 millimeters.