We are continuing in siman 21, discussing the halachos of geniza. A final question we need to discuss is whether it is muttar to place an item in geniza which is not fully balah, worn out. The language of the Shulchan Aruch when discussing geniza refers to a Sefer Torah which is balah, which we have defined as where the process to repair it would cost more than buying a new one (see shiur 1461). The implication is that until it has reached such a state, even if it is not beautiful or mehudar, the item should still be used. It would appear that putting such an item in geniza would be considered a bizayon, since the item is still usable.
The common question which comes up nowadays is what to do with a previous edition of a sefer when a newly typeset edition is printed and one wishes to purchase the new edition. Although a yeshiva may sometimes accept older seforim, that is not always the case. Similarly, many yeshivos are left with many used but fully functional seforim at the end of the year. They may be able to sell some of them, but those which they are unable to sell they may wish to place in shaimos.
This question is discussed in sefer Ginzei Hakodesh. Rav Elyashiv ztl is quoted as saying that in previous generations, if one were to discard a sefer which was not completely worn out, it was considered a bizayon, because the lack of money and resources meant that a sefer was expected to be used until it was absolutely unusable. However, nowadays, where we have such a wealth of seforim and ease to print them, if one places such seforim in shaimos, it is not a bizayon, and it is muttar.
The Chayei Adam, in Klal 11 siman 32 (see shiur here and transcript here), quotes a Sefer Chassidim regarding a sofer who wrote a yeriah of a Sefer Torah (an entire piece of parchment, usually with 3-6 columns of writing on it). Although the writing is kosher, the sofer is unhappy with the quality of his writing, and wishes to place the entire yeriah in geniza and rewrite it. The Sefer Chassidim writes that since the sofer wishes to do so for the purpose of making the Sefer Torah more beautiful, it is considered a valid purpose and is muttar.
The Chayei Adam quotes this Sefer Chassidim in hilchos tzitzis, in the context of bal tashchis. He is discussing whether one may destroy the current, kosher tzitzis on his beged in order to replace them with more beautiful strings. The question is whether one may replace the tzitzis, even though they will either be destroyed or not reused for another mitzvah. The Chayei Adam concludes from this Sefer Chassidim that it is muttar. Although it is not his primary point, we can also conclude from the Sefer Chassidim that there is no issue of placing such an item in geniza either.
The Sefer Ohel Yaakov has a long discussion about this question. One may look further in Perek 2, footnote 9. His conclusion is that one may do so, in concurrence with the psakim above.
It is muttar to place an item in geniza even if it is not fully worn out.