[quote="Michael Mutmansky"]Sandy,

"Of course, using an HO or VHO ballast will be a faster printing method, but at the substantial expense of the lamp life. Using these ballasts with normal output lamps is not recommended, and may not be electrically safe due to the much higher amperage that the lamps are operating at."

I am not advocating using normal output tubes in VHO ballast because the cost would be prohibitive. And you may well be right about the shorter life. But this combination does work and will put out more light, at least visually, than normal tubes in regular electronic ballast. Whether more useful UV light is radiated is another matter. In fact, in tests I have done there was virtually no difference in printing speed between a unit with VHO ballast and 75 watt VHO tubes and regular 20 watt output tubes in electronic ballast. The VHO unit put out a lot more visual light but it did not translate to increased printing speed. I don't know how to explain this but it is something I have tested and comfirmed several times.

"BLB lamps are essentially BL lamps with an added Wood's filter applied to the glass before the phosphers are coated onto the glass. There is no possible way that they will ever be as efficient as a BL lamp, although the difference may be slight."

The filter makes virtualy no difference in actual printing speed. There is a difference, but it is is almost miniscule (about 1/6 or 1/8 of a stop). But the difference does favor the BLs slightly. However, there is one advantage to using the BLB lights and that is the fact that the light highlights any little bits of dust and crud that might fall on your printing glass. The look is really quite amazing and really helps in reducing dust spots on the print.

"The BLB lamps don't have the majority of the visible spectrum that the BL lamps contain. This will result in a relatively 'dark' appearence to the light, which is useful if you have a bunch of phychedelic posters or whatever, but this also means that your pupils will be dialated with this light source, which can result in your eyes receiving much more UV light than with the BL (or other) lamps."

To say that the BLB are more of a danger than the BLs is confusing. Because of the filter they actually put out the same or slightly less UV light than the BLs, and in any event most of us print in rooms with the room lights on where our eyes would already be dilated and shield the light of the UV printer from our eyes (and if don'te we should).

However, if you go to a wild party where there are a lot of BLB lights strung up get some UV goggles immediately.