I have read that one should not have any material between one's tefillin shel yad and one's arm (e.g. bracelets, wristwatches). I always wear a wedding ring on the fourth finger of my left hand. I was ...
If someone, let's say, went to the beach (at night of course) and got sand in his hair and it stayed in his hair, the next morning would it be considered a Hasisa (obstacle) for Tefilin?
I've heard a man shouldn't wear anything on his left arm (as a bracelet, watch, etc) while having tefillin tied on. If this is true, would it be completely wrong to wear a red string on the left arm ...
How should one tie his shel yad on his hand if his finger(s) have something on them, such as a splint for a broken bone in the left middle finger?