No experience with this situation, but we’ve had the occasional demo idea that we politely discouraged and it went away…

If this PI is in a tenure-track position, and is not immediately receptive to your concerns and suggestions regarding safety in this situation (or others), I recommend that you document your concerns to him in writing, using whatever format is considered official communication at your institution (this may be a memo, a letter, or an email).  This document should be copied to the chair and dean (or the next couple of positions in supervisory authority --- at least).  If this is an individual who truly wants to stay at your institution, he will be responsive to valid safety concerns and will find other ways to engage his students.  If he is a “loose cannon”, his tenure committee needs to be aware of this in time to consider the implications of granting tenure.  Pre-tenure is certainly the easiest time to get this accomplished! 

If the main issue becomes the beard in general, you may eventually need to involve your university’s legal counsel and/or office of equal opportunity.  While there are many examples of industries prohibiting facial hair, doing so in an academic environment would be more difficult and should be approached carefully. 

All - Please let me know if anyone out there has had any any experience with this situation.

I have a PI who has a full beard (we are talking ZZ Top style beard here).  He is insistent on doing demos with flames - including fire eating.  Don't ask me what chemical principal that is demonstrating.  Yesterday he asked me what I thought about doing the classic "money burning" demo where you dip a  dollar in a 50/50 isopropanol/water mixture that shows how evaporation cools the money and prevents the alcohol from burning it,  only he wants to use his beard instead of the money.  I am not sure if he was serious or just trying to get a response out of me. 

Anyone have any suggestions on how to prevent this fellow from burning his face off?  In general, I would like to tell him that if the beard stays, he cannot work with flames.  Is that an option?  It is so long that he can actually tie it up and fold it in on itself, but it is still hanging pretty low and could easily catch on fire with a Bunsen burner.

Sammye