Are the laws of shatnez violated when a linen pocket square is worn with a wool suit? How about a linen tie that does not use a wool interlining?
Shalom Ronen, The Shulchan Aruch (Y.D. 300, 3-4) explains that there is no problem with sha’atnez unless the wool and linen clothes are connected well. Accordingly, a linen tie with a woolen suit is clearly not a problem. Regarding a linen pocket square, it also would be allowed based upon the precedents cited in the Rama (ibid), that one is even allowed to place old pieces of woolen clothes inside a linen pillow covering, even if it is then sewn closed. How much more so, it would be allowed in our case, where the pocket square is simply placed inside three sides of the pocket and constantly and easily removed. With Love of Israel, Rav Ari Shvat