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One good, one bad These are both large 400W UV black lights and look similar but the top one is fake. The lower is the true Iwasaki UV-cannon lamp. The upper has the label ‘UVBrite’ and has a very similar construction. However, if you look through the ‘Wood’s ‘-glass envelope at a bight light it appears deep red in the proper lamp and blue in the fake lamp. Keywords: Lamps

One good, one bad

These are both large 400W UV black lights and look similar but the top one is fake. The lower is the true Iwasaki UV-cannon lamp. The upper has the label ‘UVBrite’ and has a very similar construction. However, if you look through the ‘Wood’s ‘-glass envelope at a bight light it appears deep red in the proper lamp and blue in the fake lamp.

BL_g_by.jpg BL400.jpg 250BL.jpg PH_BL125.jpg bkl1.jpg
Lamp/Fixture Information
Model Reference:UV Black Light
Lamp
Lamp Type:mercury vapour
Burning Position:universal
Electrical
Wattage:400
File information
Filename:BL400.jpg
Album name:Tuopeek / Mercury Vapour
Keywords:Lamps
Filesize:255 KiB
Date added:16 Nov 2025
Dimensions:2500 x 1960 pixels
Displayed:70 times
DateTime Original:2025:11:16 16:52:34
Exposure Time:1/100 sec
FNumber:f/4.8
File Source:Digital Still Camera
Flash:No Flash
Focal length:40 mm
ISO:3200
Model:NIKON D3400
Software:Adobe Photoshop Elements 2.0
White Balance:0
URL:https://trad-lighting.net/gallery/displayimage.php?pid=1056
Favourites:Add to Favourites

Comment 1 to 6 of 6
Page: 1

Ria   [Sun 16 Nov 2025 at 19:41]
Hmmm, so what is the fake lamp made of then..? Not proper Woods glass I assume..?
Tuopeek   [Sun 16 Nov 2025 at 20:27]
Just looks dark like 'Woods' but definitely not. It transmits a lot of blue and green wavelengths and not all that much UV. Probably just dark blue glass.
Sammi   [Sun 16 Nov 2025 at 20:35]
IIRC, proper Woods glass weighs a good deal more. Wonder Blacklight Mercury Vapour
Tuopeek   [Sun 16 Nov 2025 at 21:15]
Thanks Sammi, I now have to go and weigh these lamps! Very Happy

The results are in; there is just 5g between then and actually the fake one is 5g heaver. I also thought the Wood's glass was heavier but I think that's from handling the GEC 175W lamp which is surprisingly heavy lamp. I guess it down to how thick the glass wall is.
Sammi   [Sun 16 Nov 2025 at 23:57]
That's what I was thunking, if the enveplop is hand-blown it will weigh more.
Max   [Mon 17 Nov 2025 at 04:28]
Interesting! Can you please post lit pictures of those lamps? Preferably with a sheet of white paper in the background and with fixed white balance and exposure settings (i.e., no auto mode)? This way we can see the differences between those two lamps during operation.

Comment 1 to 6 of 6
Page: 1