Rob,

In my experience, buying bulbs with the UV coating already on them is more expensive than buying regular bulbs and separate UV-filtering sleeves.  Additionally, when the bulbs fail (or more properly, begin to age and loose their intensity and often color balance), you can reuse the filter sleeves on the new bulbs, as long as they are still effective, which generally the newer ones are (but as always, test to be sure).  This saves a lot of money in the long run.  As to the specific bulb you inquire about, I have no personal experience, but any bulb that blocks all light below 520 nanometers will appear very red-orange, so it will have a low color temperature (definitely not daylight) and probably also will have a low color rendering index (CRI).  You can do a lot better on all accounts with your own bulbs selected for their exact purposes (and they can be different bulbs in different locations if you wish) with UV sleeves over them.

There are generally two types of UV-filtering sleeves, the rigid plastic tubes with end caps, and flexible mylar sleeves that wrap directly against the bulbs.  In theory, the flexible sleeves are less expensive, but all prices depend upon the specific vendor and what types of closeouts and specials are available at a given time.  However, it is also reasonable to assume that the quality is not necessarily the same between all brands and types.  Ask for a spectral transmission curve from the manufacturer, and for a curve after aging (this will probably be harder to get, but the good manufacturers should be able to provide it).  Be sure that the UV is adequately filtered in both curves.  If you have a reliable UV meter, you can test sample filters yourself, and can check them after real-time aging.  Yes, you can make your own sleeves from UV-filtering mylar sheets, but you will have to compare the cost of material plus labor cutting them and getting them to curl around the bulbs (tape is not ideal as it will degrade), and any waste, with the cost of buying them already made.  

Marc

American Conservation Consortium, Ltd.
     4 Rockville Road
     Broad Brook, CT 06016
     www.conservator.com 
     860-386-6058 

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