There are 3 types of tube commonly available :=20
1) 'Blacklight' - used for effects lighting -  these look black - not =
used them, they may be
suitable, but may extend exposure time=20
2) Insect killer tubes - these look while (like normal tubes) when off - =
these are the ideal type
for PCB exposure=20
3) Germicidal (also for eprom erasers) - These look transparent - they =
emit shortwave UV hazardous
to skin and eyes, and are no good for PCB exposure.


On Tue, 1 Apr 2003 11:24:00 +1200, you wrote:

>> On Tue, 2003-04-01 at 12:17, Kyrre Aalerud wrote:
>> > I use 3x 4w UV tubes and need 15 minutes for single transparancy and=
 30
>mins
>> > for double.
>> > Are you perhaps using 30w tubes ?  (I'm trying to make a small =
compact
>> > lightbox as the one I have is clearly too low power...
>>
>> My small commercially made light box has two 8W tubes and takes about =
4
>> minutes per side (it can only expose one side at a time). Maybe your
>> tubes are putting out the wrong wavelength of UV?
>
>There are "black light" UV tubes and long wavelength germicidal tubes. =
You
>want the latter.
>Black light tubes are dark almost black when off and a very deep purple =
when
>running.
>Germicidal etc tubes are usually clear and have a violent purple look =
when
>you look at them - for a few seconds anyway - don't do it !
>
>
>            RM

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