Odd effect on NOS incandescent lamp.

[samjmann]

We have a mix of the new LED and the old incandescent lamps at home. We replaced one with another old style lamp and it lasted all of 2mins. This swirling pattering happened after it had failed. Loss of vacuum maybe? The lamp is dated 2008.
Anyone seen this before?

SJM.

[cmjones01]

Yes, I'd say that was a poor vacuum. I've seen faulty incandescent bulbs do that before. The swirling pattern is, I think, the oxidised filament deposited on the inside of the glass.

Chris

[emeritus]

Agreed, the seal has failed and admitted atmospheric oxygen.
I have had several failures like this with boxes of branded GLS lamps from different manufacturers that I bought from Screwfix and RS shortly before production ceased. Unfortunately I did not bother to test them immediately. I think I had 4 or 5 of a box of 25 150W lamps GE branded lamps I had got from RS, fail, but by the time I found out, replacements would no longer have been available.

[paulsherwin]

Some production at the end of the GLS incandescent era was very poor quality.

[Hartley118]

Originally Posted by emeritus

Agreed, the seal has failed and admitted atmospheric oxygen.
I have had several failures like this with boxes of branded GLS lamps from different manufacturers that I bought from Screwfix and RS shortly before production ceased. Unfortunately I did not bother to test them immediately. I think I had 4 or 5 of a box of 25 150W lamps GE branded lamps I had got from RS, fail, but by the time I found out, replacements would no longer have been available.

This has recalled early experience of buying lamps from Woolworths - branded Sunshine or Vesta- the lamp counter had a test board with a number of connected lampholders. The sales assistant would insert the lamp, still in its packaging, into the appropriate lampholder. That would at the time at least have sorted out the infant mortalities.

Martin

[kalee20]

Yes - it looks like a bulb gone to air.

It will still work for a few seconds, but the tungsten oxidises, the oxide leaves the filament as smoke, and the convection currents and filament supports create a swirling drifting pattern like a smouldering cigarette, which settles on the glass.

And yes - I can remember Woolworths testing bulbs at point of sale, just as described! Happy days...

[samjmann]

Thanks everyone for the precise answers, and of course the memories of the Woolworths bulb sales counter. . Mod's probably better close this one before we all thread-drift down memory lane.