For studio portrait lighting, is it better to have a UV coated flashtube, or a clear flashtube, and why? Does it make a difference what ambient light there is?
Apparently the UV coating can help when photographing white material, such as a wedding dress, which can flouresce when exposed to UV and give it an undesirable bluish cast. Reference the discussion at http://photo.net/wedding-photography-forum/007pFD.
I can't claim to be an expert on this subject, but I don't see what the advantage of a clear flashtube would be (cheaper, maybe?). Whatever you do, make sure what you're doing is safe--being flashed with a bare quartz flash tube could result in a trip to the ER, according to this page.