I just learnt this today.
In the 90s, people took lots of scrap 40w and 36w 4ft tubes (surya, philips, crompton, bajaj, etc.), and cut them up. Then they put a new endcap and filament structure on one end and put vacuum in it. Those tubes were branded as suralux (I have two examples, both flawed). But they later changed the name to Sri phonix (too much backlash on suralux).
Also, these were not fully factory made, some manual labour was present. These were also not produced by one, many different groups made them and branded them as the same company (thus the inconsistencies in the etches).


As a result, those tubes would loose vacuum and have shorter life, as well as size irregularities.


Also, alfa used these tubes to make their coloured and standard tubes, thus I am lucky to have one (in gold, all my red ones lost vacuum) which is nos.


The common sizes were- 3ft 30w, 2ft 18/20w, 1.5ft 15w, 15" 14w and 1ft 10w.


If any other country or region had a similar technique, please share your story.




Links-
https://www.lighting-gallery.net/gallery/displayimage.php?album=8026&pos=34&pid=243862 (Sri phonix 15w T12, correct size, colour and tube)
https://www.lighting-gallery.net/gallery/displayimage.php?album=8026&pos=160&pid=235565 (suralux 10w T8, correct size and colour, but scratched phosphor and no emmition coating on the filaments)
https://www.lighting-gallery.net/gallery/displayimage.php?album=8026&pos=171&pid=235349 (suralux '15w 6500k' correct tube but size is of an F14T8 not F15T8, and the colour is close to 5000k not 6500k)
https://www.lighting-gallery.net/gallery/displayimage.php?album=8026&pos=192&pid=235145 (alfa 20w T12 gold, everything good exept etch is wrong and slight contamination inside the tube)

I have not heard of fluorescent tubes being repaired before on a commercial basis - although sometimes university glassblowers in Britain would cut up old fluorescent tubes to make vacuum physics research devices.

Repair of incandescent lamps was quite a huge business though.  In fact Sylvania company started out that way, it would buy dead lamps from other manufacturers, cut a hole in the top, clean the glass and repair the filament, then re-pump and sell at profit.  The practice died out in Britain and America around the 1920s because increasing automation made it cheaper to make a new lamp, but it’s logical that in lower cost countries it would have continued until more recently.

Imagine if they repaired coloured phosphor tubes, that would have been nice since surya made red, green and blue F40T12s at the time.
Incandescent repair wasn't present exept poor villages with less access to cities. Cost of new bulb is less than a repaired one.

It seems silly, but someone probably got the idea from CRT (picture tube) rebuilding and applied it to lamps. For those that aren't familiar with picture tube rebuilding, this process lets air into the tube, cuts off and replaces the electron gun, and vacuums the tube back down. This allowed the tube to be used again. Very important, especially back in the days of early color TV where a picture tube may need replaced every two or three years.