1) WRITING ON TOP OF "SIKRA"
QUESTION: Reish Lakish asked Rebbi Yochanan about having witnesses sign a Get when those witnesses do not know how to write. May Beis Din write the witnesses' names with Sikra and then instruct the witnesses to sign on top with ink. Since writing with ink on top of Sikra is considered a valid act of writing with regard to Shabbos, is it also considered a valid act of writing for a Get? Rebbi Yochanan answered that only with regard to Shabbos did he rule stringently that there is a concern that it is a valid act of writing. He did not rule leniently that it is a valid act of writing with regard to a Get.
TOSFOS (DH Dayo) points out that ink written on top of ink certainly is not a valid form of writing for a Get. He questions this from the Gemara later (20a) which says that if one signed a Get without proper intent (she'Lo Lishmah), he may sign again over his signature and make his signature Lishmah. Why is the second signature valid if ink on top of ink is not considered an act of writing? Tosfos answers that ink on top of ink is not considered an act of writing only when the second writing adds nothing to the validity of the Get. When the second writing adds validity to the Get (such as when the second writing is Lishmah), it is considered a valid act of writing.
How does Tosfos understand the Gemara here? The Gemara suggests that Sikra be used to make rudimentary signatures for the witnesses to write over with ink, so that their signatures will be considered a proper writing. Why does the Gemara say that such an act is not considered writing? The initial writing with Sikra is not a testimony at all, and thus it should be no different from a writing done she'Lo Lishmah, in which case a writing of Lishmah on top is considered a writing and the Get is valid! (Acharonim)
ANSWERS:
(a) The MAHARSHA answers that Rebbi Yochanan and Reish Lakish do not agree with the ruling of the Gemara later. They maintain that a Ksav on top of a Ksav is not a valid Ksav even when the second Ksav adds some element of validity to the Get.
(b) The KARNEI RE'EM explains that a signature written Lishmah on top of a signature written she'Lo Lishmah is a valid act of writing and testimony, but it is an "Edus she'Iy Atah Yachol l'Hazimah" -- it is a form of testimony which is not subject to disproof through Hazamah. This means that if the signatory is discovered to have been somewhere else at the time he claims that he signed the Get (and thus he could not have been a witness to it), his signature does not constitute false testimony; rather, there is no signature or testimony on the Get.
If such a signature does not add any element of validity to the Get, it is considered a Ksav on top of a Ksav, which is not a Ksav at all. Since it is not a testimony which is subject to Hazamah, it is not considered a valid testimony at all.
(c) REBBI AKIVA EIGER answers that the Gemara later is discussing the writing of the Get. One of the Torah laws of writing a Get is that it must be written Lishmah. To fulfill this requirement, a second writing performed over the first suffices. In contrast, the Gemara here refers to the signing of a Get. Mid'Oraisa, the signing of a Get does not need to be Lishmah, according to the opinion that "Edei Mesirah Kartei." The signatures are necessary only to attest that what is written in the Get is true. The requirement that the signatures be Lishmah is mid'Rabanan. Accordingly, a second signature done Lishmah on top of a first signature that was not done Lishmah does not fulfill the Rabanan's requirement of Lishmah to make the Get valid.
(d) RAV ELYASHIV shlit'a answers that Tosfos' principle -- that when the second Ksav adds some element of validity to the Get, the second Ksav is valid -- applies only when the first Ksav was a Ksav lacking validity. A new Ksav can validate the first Ksav by adding the necessary element of Lishmah. However, when the first Ksav is not considered a Ksav at all -- such as where Beis Din fashioned the signatures of the witnesses -- the second writing is not considered a writing at all.
(e) RAV CHAIM KAMIL zt'l (quoted in OHALEI YITZCHAK) answers that the second Ksav is a valid Ksav only in the case of the Kesivah of a Get. Since the Get must be written Lishmah, a new writing which is Lishmah is considered a higher level of writing and makes the Get valid. Since the Get must be written Lishmah, a second Kesivah which adds the element of Lishmah is considered a new, valid writing.
In contrast, the signature on a Get is needed only to attest to what is written in the Get. The requirement that the Chasimah must be Lishmah is merely due to the requirement that the testimony be Lishmah. Accordingly, a second act of signing Lishmah does not establish a new level of writing, but only a higher lever of testimony. Therefore, the addition of Lishmah in the Chasimah is not considered a new writing to make the Get valid. (Mordechai Zvi Dicker)

19b----------------------------------------19b

2) A GET WRITTEN WITH INVISIBLE INK
QUESTION: Shmuel rules that when a man gives a blank piece of paper to his wife and says, "This is your Get," she is divorced because "we are concerned that it was written with Mei Milin." The Gemara questions Shmuel's ruling from a Beraisa which states that if one gives a document with writing on it to his wife and says, "This is your Get," and afterwards he claims that it was not a Get but another type of contract, she still is divorced. This implies that if he gave her a document with no writing on it, she would not be divorced, in contrast to Shmuel's view.
The Gemara answers that in Shmuel's case, Beis Din examined the document after it was given and treated it with "Maya d'Nara" which revealed that the text of a Get indeed was written on the parchment with Mei Milin, which had become absorbed into the parchment. The Gemara asks that if this is the case, why does Shmuel say that she is divorced? Perhaps the words of the Get were absorbed already at the time the Get was given, and she should not be divorced! The Gemara answers that Shmuel himself said only "Chaishinan," it is treated like a Get out of doubt, but the woman is not definitely divorced.
If, as the Gemara explains in its conclusion, Shmuel ruled that the woman's divorce is only a doubtful one, why does the Gemara need to say that Beis Din examined the document? Even without an examination it is logical to be concerned that the document contained the text of a Get!
ANSWERS:
(a) Tosfos (DH u'Shmuel) explains that the Gemara indeed no longer needs to rely on its previous assertion that Beis Din examines the document. Once the Gemara says that Shmuel ruled that the woman is divorced only out of doubt, it no longer needs to say that Beis Din examined the document. The Gemara earlier required an examination only because it originally understood that Shmuel meant that she is definitely divorced (Vadai Gerushin).
(b) The RASHBA challenges Tosfos' explanation. According to Tosfos, since the Gemara is giving a new answer and no longer relies on its previous answer, the Gemara should add the words, "Ela Shmuel Nami" -- "rather, Shmuel also said only that we are concerned that it might be a Get." The Gemara's omission of the word "Ela" implies that the Gemara still needs its earlier answer, that Beis Din examines the Get, and only in such a case does Shmuel rule that she is divorced out of doubt.
The Rashba, therefore, concludes that if Beis Din did not examine the Get, there is no concern whatsoever for Gerushin, and she is not divorced even out of doubt. Since no writing was seen on the Get, no doubt even begins, and thus there is no basis to be stringent out of doubt.
(c) REBBI AVIKA EIGER is bothered by a different point. The Gemara originally challenges Shmuel's ruling from the Beraisa which implies that when no writing was seen on the parchment given as a Get, the parchment is not assumed to be a Get written with Mei Milin. This implies that if the husband's word (that the document is a Get) would be believed, the Get would take effect beyond a doubt and there would be no concern that the letters were absorbed into the parchment already at the time of the Gerushin.
Why, then, when the Gemara proposes that Shmuel refers to a case in which Beis Din examined the parchment and found that the Get was written with Mei Milin, does the Gemara ask that perhaps the letters were absorbed into the parchment at the time of the Gerushin? Why does the Gemara earlier not consider this a serious concern, but now it does consider this a serious concern?
Rebbi Akiva Eiger suggests an answer as follows. From the beginning of its discussion, the Gemara understands that if a Get is written on this document, even it if is presently invisible (because the letters were absorbed into the parchment) the Get is valid. The Gemara's only question was that the Beraisa implies that the husband is not believed to testify that a Get is written on the parchment.
This assumption, that the "invisible" Get is valid, changes in the next stage of the Gemara. Once the Gemara determines that Shmuel's ruling refers to a case in which we know that the parchment contains a Get, the word "Chaishinin" does not make sense. The Gerushin certainly should take effect, and not merely take effect out of doubt! In order to understand Shmuel's words, the Gemara explains that the words of the Get must be visible at the time of the Gerushin. "Chaishinin" means that there is a concern that the words were visible at that time. The Gemara questions whether this is true or not, and it answers that Shmuel's ruling was only "Chaishinin," she is divorced mi'Safek and has a status of a Safek Megureshes.
Rebbi Akiva Eiger adds that according to the Gemara's conclusion, the original assumption remains intact: the words of the Get need not be visible at the time of the Gerushin. Shmuel refers to a case in which Beis Din did not examine the Get (and thus he says "Chaishinin"); his ruling is not contradicted by the Beraisa because the Beraisa refers to Vadai Gerushin while Shmuel refers to Safek Gerushin. For the Gerushin to take effect beyond a doubt, Beis Din indeed would need to examine it, but for the Gerushin to take effect out of doubt no examination is necessary (as Tosfos writes). (Mordechai Zvi Dicker)