Tumah after deciding not to "finish" an object

Question

In Keilim 16:1, the mishnah asks when wooden utensils are susceptible to tumah. The anonymous mishnah describes a bed or cot, and that it becomes susceptible after sanding; however, if the owner decided not to sand it, it becomes susceptible without the sanding. See the following extract:

כְּלֵי עֵץ, מֵאֵימָתַי מְקַבְּלִין טֻמְאָה. הַמִּטָּה וְהָעֲרִיסָה, מִשֶּׁיְּשׁוּפֵם בְּעוֹר הַדָּג. גָּמַר שֶׁלֹּא לָשׁוּף, טְמֵאָה.

When do wooden vessels begin to be susceptible to impurity? A bed and a cot, after they are sanded with fishskin. If the owner determined not to sand them over they are susceptible to impurity.

Much of the rest of chapter 16 further discusses this question for other utensils, but doesn't add the statement where the owner decides not to "finish" the utensil as usually would be done.

Does the same idea apply in all the cases, so that when an owner decides not to put the usual finishing touches on their utensil, it becomes susceptible (regardless of when the mishnah says it's "finished")? If not, why are beds and cots different?

I would guess that it applies in general, but we see repetition of laws in many cases in Keilim where we would expect a single case to suffice. Thus, I'm wary about making unwarranted generalisations here.

Answer 1

I think we can possibly answer this question by looking at the commentary of the Bartenura there:

משישופם בעור הדג. להסיר קסמין שבהם, דקודם לכן לא חזו למלאכתן, שמשרטים את הבשר. אבל אם אינן מחוסרין אלא שיפה של צחצוח ומריקה, הא קיימא לן [חולין כ״ה] דגולמי כלי עץ שעתיד לשבץ ולשוף טמאין

It seems that sanding is considered the completion of the work because that's how the worker removes the splinters from the wood. Without doing that, the bed is not fit for use and is not considered a vessel for the purpose of receiving impurity. However, if the bed somehow doesn't need sanding in order for it to be usable (just to make it look nicer), then it's considered to be in the category of גולמי כלי עץ שעתיד לשבץ ולשוף, which Bartenura says is susceptible to impurity (I didn't go look up the gemara in Chulin). That's how I understand the Bartenura.

So it seems that this din isn't really such a big surprise. In this case, the reason the artisan did not apply the usual finishing touches was because they were not necessary to make the vessel fitting for use. If the bed had splinters still, it wouldn't become susceptible to impurity until it was sanded, regardless of what the worker planned to do. The other finishing touches in this chapter seem to be of the type that is required to make the vessel fitting for use. By our logic, the vessels would not become susceptible to impurity if the worker decided to skip them because the items would not be sufficiently usable.