Fold in the Matzah and Inflated Matzah
Folds
27. Sometimes, during the baking, part of the matzah folds over onto itself. The poskim were concerned – as a chumra (חוק יעקב סקי"ח, שעה"צ תסא סקנ"ז ) – that the part of the matzah which folded over and stuck to itself did not get fully baked and may become chometz (רמ"א תסא ס"ה ).
28. If this matzah was baked on Pesach, the entire matzah is forbidden. If, as is more common, it was baked before Pesach, only the area of the fold (רמ"א שם ) and its immediate surroundings (מ"ב סקל"ב ) – two cm. according to Rav Chaim Naeh – are forbidden. One can rely on Rav Chaim Naeh's measurement since this whole concept is a chumra.
29. Some differentiate between thick and thin matzos. They hold that the poskim were only worried that the fold of a thick matzah dough would not get fully baked, but by thin dough [like that which is made nowadays], we assume that even the fold got fully baked (שו"ת רדב"ז ח"א תצד, דע"ת למהרש"ם ). Still, the custom is to be machmir even by thin matzos (מו"ר בשו"ת קנה בשם ח"א סי' כג ).
Types of Folds
30. With air space. If the matzah folded, but did not attach to itself; rather, it left a gap of air space in the fold – even a tiny space (שו"ע הרב ) – it is not forbidden, as the fire comes into contact with all of the matzah, assuming the inner surface of the fold crusted over (מ"ב סקכ"ה ). If it did not, the matzah is forbidden mideoraisa (מ" ב סקט"ו ). If one is uncertain if it crusted over, since it is a potential issue deoraisa, it is forbidden (מ"ב שם ).
31. Without air space. If the top of the fold is in contact with the bottom, but not attached, that part of the matzah is forbidden (שעה"צ סקמ"ג שו"ע הרב סי"ט וכ"ב, שו"ת קנה בשם שם ). This commonly happens when the matzah is placed into the oven.
32. Slight connection. Sometimes the top of the fold connects to the bottom to the extent that, when separated, strands of dough stretch out. This is more common by soft dough; less so with our matzos which are made with firm dough. In this case, some consider it thick dough as opposed to a fold in the matzah, and permit it if there is an additional reason to be lenient (חמד משה הובא בביאה"ל תסא ד"ה זו על זו ). Perhaps the opinion that is lenient on today's thin matzos (29) can also be taken into consideration.
33. Some are machmir since this type of connection is considered a fold, not one piece of dough (חזו"א או"ח קב סק"י, שו"ת קנה בשם שם אות ב ).
34. Fold made while flattening the dough. If a fold was pressed so tightly that it is impossible to separate the upper and lower parts, as if it had been kneaded together, it does not invalidate the matzah. It happens often while flattening the dough that a bit of dough folds over and gets flattened together until only a faint line is visible. This matzah may be eaten on Pesach.
35. Some poskim are machmir even in such a case (חזו"א, דינים והנהגות פי"ז ס"א, ארחות רבינו ח"ב עמ' נד ). However, most poskim are meikel, and even the Chazon Ish was only machmir for himself (חוט שני פסח פי"ב סק"י ).
Matzos on Top of Each Other in the Oven
36. If one matzah, or even part of a matzah, rested on top of another matzah in the oven, both matzos are forbidden at the point of contact, as the fire cannot get to that part of the dough (רמ"א תסא ס"ה ).
37. Whilst placing Matzos in the oven, one should ideally prevent those matzos from touching the matzos already in the oven. However, if they did touch, they do not become forbidden since they do not attach and are separated right away (חזו"א או"ח סי' קב סקי"ז ד"ה ונראה ).
Matzos Touching Each Other
38. If two matzos are next to each other in the oven and are touching at their edges, they may be eaten on Pesach because the fire touches the whole bottom surface (מ"ב סקל"ח ). Still, it is best to try to avoid any contact (רמ"א שם ).
Inflated Matzah
39. Matzah which is inflated in the middle is forbidden (רמ"א תסא ס"ה ). There are two interpretations of "inflated": 1) a pocket of air developed between the top and bottom of the matzah, or 2) a section of the matzah rose without the top and bottom separating. One must be machmir by both (מ"ב סקל"ג ).
40. Air pockets or risen sections only invalidate the matzah if they have the width and height (הגרי"י קנייבסקי, ארחות רבינו ח"ב עמ' נה ) of a hazelnut or the average thumb (מ"ב סקל"ד ). In modern-day terms, that is 2 cm. [Rav Chaim Naeh] or 2.2 cm. [Chazon Ish].
41. When a section of the matzah inflates, the entire matzah is forbidden, even if it was baked before Pesach (מ"ב סקל"ד ), because the inflation indicates that the dough was not worked enough to prevent it from starting to become chometz (שו"ע הרב סכ"ה ).
42. An air pocket in the middle [1st interpretation] only invalidates the matzah if the top and bottom parts are of equal thickness. If, as is common, the bottom part is thick and the top is thin like a membrane, it is permitted (רמ"א שם ומ"ב סקל"ה ).
Modern-Day Matzos
43. Some say inflation is only a problem with thick matzos; not with our thin matzos, because the fire's heat is strong enough to prevent them from becoming chometz (שע"ת סקט"ו והובא במ"ב סקל"ה ), especially when the top part is very thin (42) (שו"ת קנה בשם ח"א כד ). However, if the place of inflation is visibly under-baked, it is customary to break off that area (מצות מצוה פ"ט הערה כט ).
44. Also, when a section of today's matzos rises [2nd interpretation], they may be eaten on Pesach because the rising is not due to chometz; rather it is due to too few holes or the strength of the fire (ע רוה"ש סי"ב ).
Inspecting Matzos
45. Generally speaking, factories with a good hechsher appoint someone to check each matzah for folds or inflation, avoiding any possible concerns. Nevertheless, it is a good idea for each person to check his matzos, as sometimes shailos arise.
