When Nakaya made my pens, they told me not to post the cap for six months since posting the cap before this time period could destroy the finish. I never post my caps, so I didn't really pay much attention, but I think after some time, the finish ages and becomes more beautiful.
I think that if the pen is brand new, people who are sensitive should wait some months for the finish to cure completely. The pen is also made from hard rubber, but I haven't had any problems although I'm latex allergic.
If it makes any difference, I ordered my pens from Japan, and they make sure to warn you, but since I have family in that part of the world, but not necessarily in Japan proper, we are fairly well versed about the effects of uncured urushi. Once fully cured, there should be no problem even for people who have bad allergic reactions in general. I have family with bad allergic reactions who have used my Nakaya pens that I have had for more than a year but haven't had any ill effects.
Edited by Dillo, 07 July 2013 - 03:00.