http://revach.net/article.php?id=779

Section: Halacha   Category: Tshuvos
Rav Moshe Feinstein and Rav Moshe Shternbuch: Dyeing Your Beard To Look Younger For a Job Interview

There is an issur Min HaTorah for a man to beautify himself like a woman which includes wearing clothing of the opposite sex, shaving hair that woman normally shave, and various other cosmetic acts.  The Bach (YD 182) says that a man can wear a woman's clothing if his intention is only to keep cool in the sun or warn in the cold and not to beautify himself.

With regard to dyeing the white hairs of beard in order to be accepted for a position meant for a younger person Rav Moshe Feinstein says that since the purpose is to earn a living and not to look like a woman and that even after dyeing your beard you will not look like a woman since all other aspect of your appearance clearly show that you are a man, it is permissible.  (Rav Moshe only permits this if there is no issur of ona'ah and you are actually capable of performing the job like a younger person.)

Rav Moshe Shternbuch disagrees.  He distinguishes (1:461) between the two case.  In the case of the Bach your whole intention of wearing woman's clothing is not to beautify yourself but only to protect yourself from the weather conditions.  But in the case of dyeing your beard for work your purpose is to beautify yourself although for the legitimate cause of earning a living.  The latter he holds is not permitted. 

If the white hairs are growing wildly Rav Shternbuch permits cutting them since it is not to beautify yourself only to avoid looking strange and disgusting.

Important Note: Our only goal is to introduce a interesting Sheilah and not pasken Halacha.  We try to convey the Tshuva to the best of our ability. We admit that our understanding may not be accurate. Please also understand that this Tshuva may not be the final word on this topic. One should consult a Rav before drawing any conclusions.