Mishnah 9 opens with the law of the "keses hasabalim" - a small cushion that a porter, who carries heavy loads, places on his shoulder so that the load will not injure his skin as he carries it. Its law: "temei'ah midras" - it is susceptible to midras tumah, because the porters sometimes take this cushion off their shoulder and use it as a seat to sit on.
"Mishmeres shel yayin - ein bah mishum moshav" - a wine strainer is not susceptible as a seat:
The mishmeres is a cloth through which wine is strained: the wine pours through it and falls into a tub underneath, while the dregs, the skins and the sediment remain in the cloth, which functions as a filter. Since there is no way to sit on the mishmeres at all, it is never susceptible to midras tumah or to the tumah of a seat.
"Sevachah shel zekeinah - temei'ah mishum moshav" - the hairnet of an elderly woman is susceptible as a seat:
The sevachah is a type of head covering worn by an older woman. It is susceptible to tumah because the woman sometimes removes the covering from her head and sits on it, using it as a seat. But this ruling is difficult: in chapter 24, Mishnah 16, we learned that it is specifically the hairnet of a young girl that is susceptible to midras tumah, since she removes the covering from her head and sits on it from time to time, whereas the hairnet of an elderly woman is susceptible only to corpse tumah and not to midras tumah, because she is not in the habit of removing it from her head. Yet our Mishnah states explicitly that the hairnet of an elderly woman is susceptible as a seat. How are the two reconciled?
Two approaches have been offered to resolve the contradiction:
Two types of hairnets: There are two kinds of head coverings that older women wear. The Mishnah in chapter 24 is speaking about the kind that is not sat upon, and therefore it is not susceptible to tumah; here, however, the reference is to a different kind, which the woman does use for sitting from time to time, and therefore it is susceptible as a seat. This is the approach of the Rambam, and the Bartenura follows him.
Emending the text: Others change the reading of the Mishnah in chapter 24 and read there: that of an elderly woman - susceptible to midras, and that of a young girl - susceptible to corpse tumah. That is, the young woman does not remove her hairnet, while the older woman does remove it, and therefore her hairnet is susceptible to midras tumah. According to this emendation, the text there fits perfectly with what is said here, that the hairnet of an elderly woman is susceptible as a seat.
"Chaluk shel yotzei hachutz he'asuy kesevachah - tahor" - the garment of a woman who goes out, made like a hairnet, is pure:
The "yotzeis hachutz" is a harlot, and the chaluk is the dress or robe she wears, made so loosely that it is see-through. If the chaluk is made like a hairnet, that is, woven as a loose net - it is pure and not susceptible to tumah, because it is not considered a proper garment.
"Ha'oseh beged min hacherem - tahor, umizuto - tamei" - one who makes a garment from a net is pure, and from its lower portion is impure:
From the cherem: The cherem is a net used to catch fish, and it has large holes. One who makes a garment from it - it is pure and not susceptible to tumah, for the same reason that the garment of the harlot is pure: it cannot be worn, since it is full of holes and see-through, and one can see through it because of the large holes in it.
From the zuto of the cherem: As we learned earlier, in the nets of the Mishnaic period there was a portion at the bottom of the net that was not made as a net full of holes, but rather as a woven piece of cloth, perhaps in order to weigh the net down somewhat, and this is what is called the "zuto shel cherem." One who makes a garment from that zuto, which is woven like a garment - it is impure and susceptible to tumah.
"Rabbi Eliezer ben Yaakov omer: af ha'oseh beged min hacherem vekiflo - tamei" - Rabbi Eliezer ben Yaakov says: even one who makes a garment from a net and doubled it - it is impure:
If someone takes a net and covers himself with it as it is, one can see through it; but if he folded it over several times until it is no longer transparent and one cannot see through it, it is susceptible to tumah, since from now on it is considered a garment.
With this we have completed Mishnah 9. In the next section we will move on to Mishnah 10, the final mishnah of chapter 28, and then begin chapter 29.