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Dead phosphor crystal in NOS unused soviet PZGRL (Poltava) F80T12 tube

Dead phosphor crystal in NOS unused soviet PZGRL (Poltava) F80T12 tube

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How ridiculous is that? Wheres the quality control? Why the coating is so grainy? Why are there dead crystals? The answer is simple: It's Poltava factory my dudes! Poltava factory in Ukraine was notoriously known in all of USSR for it's sheatty quality and short life lamps.

IMG_20191219_203146.jpg IMG_20191219_150414.jpg IMG_20191219_144407.jpg IMG_20191212_182854.jpg

Light Information

Light Information

Manufacturer:PZGRL (Ukraines Poltava gas discharge lamp manufacturing plant)
Model Reference:LDC 80

File information

File information

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Filename:IMG_20191219_144407.jpg
Album name:vytautas_lamps / fluorescent tubes T8/T12
Keywords:Lamps
File Size:392 KB
Date added:Dec 19, 2019
Dimensions:2464 x 1848 pixels
Displayed:76 times
Date Time:2019:12:19 14:44:08
DateTime Original:2019:12:19 14:44:08
Exposure Bias:0 EV
Exposure Time:8330/1000000 sec
FNumber:f 1.8
Flash:No Flash
Focal length:3.5 mm
ISO:160
Make:Blackview
Model:BV6000S
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merc
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Dec 19, 2019 at 11:38 AM Author: merc
Would be interesting to see what light quality it gives off.

Not a misoLEDist...

vytautas_lamps
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Dec 19, 2019 at 11:56 AM Author: vytautas_lamps
Have in mind that the tube was lit during photographing, with no flash so you can safely assume, that the tub light output is total grbage

New lighting technologies is a pity fest everywhere you look. From LEDs that last only for two months, to a never-ending global starvation of t8 fluorescent tubes.
We shall reinforce ourselves with good old full mercury t12s and HIDs made to surpass one's life, and give them all the middle finger ;

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Dec 19, 2019 at 01:49 PM Author: James
This phenomenon is actually caused by letting the phosphor suspension liquid stand still for too many hours before painting it onto the tube inner surface. The phosphor consists of microscopic particles of powder, and over time after mixing with a liquid binder they migrate together into small lumpy agglomerates. The UV cannot penetrate deep into these and they therefore fluoresce less. The result is that the weight of phosphor coated into a lamp increases for a given lumen level and such lamps are not cost-efficient, because the phosphor is quite expensive.
vytautas_lamps
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Dec 19, 2019 at 02:11 PM Author: vytautas_lamps

This phenomenon is actually caused by letting the phosphor suspension liquid stand still for too many hours before painting it onto the tube inner surface. The phosphor consists of microscopic particles of powder, and over time after mixing with a liquid binder they migrate together into small lumpy agglomerates. The UV cannot penetrate deep into these and they therefore fluoresce less. The result is that the weight of phosphor coated into a lamp increases for a given lumen level and such lamps are not cost-efficient, because the phosphor is quite expensive.

I have seen this happen in modern tubes as well. In sylvania tubes, some of them have these dead phosphor crystals in them. Or the Hungarian GE t8s. Them also had dead particles. But more not than often, you rarely see tubes with that defect, but they are somewhat common.

New lighting technologies is a pity fest everywhere you look. From LEDs that last only for two months, to a never-ending global starvation of t8 fluorescent tubes.
We shall reinforce ourselves with good old full mercury t12s and HIDs made to surpass one's life, and give them all the middle finger ;

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Rare white reflector


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Dec 19, 2019 at 11:22 PM Author: Silverliner
The Philips T12s made in Mexico had a pretty grainy phosphor finish.

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Dec 20, 2019 at 06:58 AM Author: rjluna2

This phenomenon is actually caused by letting the phosphor suspension liquid stand still for too many hours before painting it onto the tube inner surface. The phosphor consists of microscopic particles of powder, and over time after mixing with a liquid binder they migrate together into small lumpy agglomerates. The UV cannot penetrate deep into these and they therefore fluoresce less. The result is that the weight of phosphor coated into a lamp increases for a given lumen level and such lamps are not cost-efficient, because the phosphor is quite expensive.

That's interesting, James. Apparently, they didn't know about the life into the phosphor suspension liquid could diminished the quality of coating the envelope

Pretty, please no more Chinese failure.

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Dec 20, 2019 at 01:30 PM Author: James
Its pretty well known that the suspension has to be used quickly, however production pressures sometimes get in the way. For instance if you have already mixed up a $10k vat of phosphor and then the lampmaking machinery suffers a breakdown which might take some hours to repair, there is not so much motivation to pour the suspension down the drain and mix up a new batch! Some companies have discovered that certain kinds of deflocculant chemicals can be added to the suspension in such cases, to extend its life and reduce agglomerates - but maybe PZGRL either did not know or care about such things!
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Dec 20, 2019 at 01:40 PM Author: vytautas_lamps

Its pretty well known that the suspension has to be used quickly, however production pressures sometimes get in the way. For instance if you have already mixed up a $10k vat of phosphor and then the lampmaking machinery suffers a breakdown which might take some hours to repair, there is not so much motivation to pour the suspension down the drain and mix up a new batch! Some companies have discovered that certain kinds of deflocculant chemicals can be added to the suspension in such cases, to extend its life and reduce agglomerates - but maybe PZGRL either did not know or care about such things!

Probably they didn't care about it.. But, the tube was made in 1985 so maybe back then such chemical weren't invented already.. who knows.

New lighting technologies is a pity fest everywhere you look. From LEDs that last only for two months, to a never-ending global starvation of t8 fluorescent tubes.
We shall reinforce ourselves with good old full mercury t12s and HIDs made to surpass one's life, and give them all the middle finger ;

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