Just as the wool for tzitzis has to be spun lishmah by Jews, so does the silk for making silk tzitzis. But here there is problem. Spinning silk is a specialised activity involving extremely delicate work and almost all the silk thread in the world is spun in China by experts who are non Jews. However in Italy, there are Jews who know how to spin silk, and indeed there are Italian Jews who wear tzitzis made from silk threads. (see: Mishpacha, English edition, 2 November 2011, page 60)

Although one may leave the eiruv wearing tzitzis on Shabbos, there are some limitations. If some (but not all) of the tzitzis are posul, one may not go outside the eiruv wearing such a beged. According to some opinions, if the beged is below the minimum size, one may also not go outside the eiruv wearing it. (Mishnah Berurah 13:2) What about a garment which is not made of wool and therefore one only has to attach tzitzis mi’drabbonon? On this Reb Mottel Tenenbaum, who is an expert on tzitzis and author of the “Hadar Tzitzis” series writes, “Some people wear a wool one on Shabbos so they don’t have problems of carrying because that’s a real beged, no question about it.” (Mishpacha, English edition, 14 December 2011, page 78)