(Mishnah): We may not use pitch or wax.

Until here [the Mishnah lists Pasul] wicks. From here (these) and onwards [it lists Pasul] oils.

(R. Avahu citing R. Yochanan): [These wicks and oils are forbidden] because the flame is drawn back (does not cling to the wick), and he will forget [that it is Shabbos] and remove the wick (to fix it so it will burn better);

Also, the majority of the Delek (the part of the wick that sticks out of the oil) does not catch fire (so it is prone to extinguish).

Question (R. Ze'ira): If so, we should infer that in a wick, the majority of the Delek must catch fire!

Answer: Indeed, R. Shmuel came and cited R. Avahu in the name of R. Yochanan to say that in a wick, the majority of the Delek must catch fire.

Question #1 (Talmidim): For wax, [we permit even though] the majority of the Delek did not catch fire!

Question #2 (R. Ba bar Mamal): For Chelev, [we permit even though] the majority of the Delek did not catch fire!

Answer (to both questions - R. Shamai): R. Ze'ira cited Rav Yehudah citing Rav said that there are four fires for which any amount suffices (we do not need a majority) - a fire of Gefes, of manure, of Chelev, and of pits, any amount suffices. (Wax is like Chelev.)-

Support - Also, R. Tachlifa asked Rav Chisda - didn't Rebbi teach us that Shabbos during Chanukah, we may not light [Ner Chanukah] with the wicks and oils that Chachamim said that we may not light them on Shabbos;

One may not look at a coin using the light of Ner Chanukah. He will not forget and remove the wick (since he may not use it)!

Conclusion: [In this case] the reason we may not use them is only because the majority of the Delek does not catch fire! (We can say that for Ner Shabbos, there is also concern for tilting.)

(Mishnah): And not Kik oil.

Opinion #1 (R. Yosi citing R. Liya): This is cottonseed oil.

Opinion #2 (R. Yonah citing R. Ze'ira citing Rav Yehudah): It is [fat of] a bird called Kik.

(Beraisa - R. Yishmael): "V'Es ha'Ka'as'' - this is the Kik bird.