Sooo today I got myself an NOS soviet 250 watt incandescent heat lamp.. I turned it on and what I observed boggled me. I turned the lamp on, probably for the first time since 1984 and inside the lamp a strange vortex of slightly white vapor started coming off the filament.. I immediately thought that it might be air leak, but as it continued to burn, the filament stopped vaporizing and the remaining vapor was just circulating inside the lamp itself.. I left the damn thing on for 10 minutes and same vapor was still rising and falling but the lamp was okey as any normal incandescent lamp.. What in earth's name is going on?? Has any of you seen this? I tried my damn hardest to try and make a video of that vapor but my camera Just. Does. Not. Want. To. Pick. Them. Up.  Has any of you seen such an effect in a incandescent lamp, and if so, what could be the cause of it? Maybe some impurities got burned out from the filament? or maybe there was some moisture inside the lamp?? Thank you for replies in advance 

Sooo today I got myself an NOS soviet 250 watt incandescent heat lamp.. I turned it on and what I observed boggled me. I turned the lamp on, probably for the first time since 1984 and inside the lamp a strange vortex of slightly white vapor started coming off the filament.. I immediately thought that it might be air leak, but as it continued to burn, the filament stopped vaporizing and the remaining vapor was just circulating inside the lamp itself.. I left the damn thing on for 10 minutes and same vapor was still rising and falling but the lamp was okey as any normal incandescent lamp.. What in earth's name is going on?? Has any of you seen this? I tried my damn hardest to try and make a video of that vapor but my camera Just. Does. Not. Want. To. Pick. Them. Up.  Has any of you seen such an effect in a incandescent lamp, and if so, what could be the cause of it? Maybe some impurities got burned out from the filament? or maybe there was some moisture inside the lamp?? Thank you for replies in advance 

I think a small amount of air was sealed in the bulb and then burned it.

Sooo today I got myself an NOS soviet 250 watt incandescent heat lamp.. I turned it on and what I observed boggled me. I turned the lamp on, probably for the first time since 1984 and inside the lamp a strange vortex of slightly white vapor started coming off the filament.. I immediately thought that it might be air leak, but as it continued to burn, the filament stopped vaporizing and the remaining vapor was just circulating inside the lamp itself.. I left the damn thing on for 10 minutes and same vapor was still rising and falling but the lamp was okey as any normal incandescent lamp.. What in earth's name is going on?? Has any of you seen this? I tried my damn hardest to try and make a video of that vapor but my camera Just. Does. Not. Want. To. Pick. Them. Up.  Has any of you seen such an effect in a incandescent lamp, and if so, what could be the cause of it? Maybe some impurities got burned out from the filament? or maybe there was some moisture inside the lamp?? Thank you for replies in advance 

If bulb still works then it can be phosphorus burning from filament which sticks to glass and keeps vacuum inside.After 36 years this is normal.If you want to see is yout bulb holding vacuum fill some bucket with tap water and submerge bulb in water.Is bulb working ? Can you capture the bulb while it's off and try to put bulb on white wallpaper? WARNING
If something happens to bulb I'm not responsible.Do it at your own risk.Message for all people from me

If it is moisture then it will keep removing Tungsten from the filament, like a reverse Halogen cycle. What happened to it after it was switched off ?

I think it is probably just the getter, I have seen this on a few older lamps and it also occurs in the factory on every new lamp that is made.  If the factory sent the lamp out without ever lighting it, then the customer will see this effect.  See towards the end of this video of the Philips Pila GLS factory.

  If the lamp does have a tiny air leak then the glass bulb will gradually acquire a blueish coating of the low tungsten oxide W2O5.  If there is a moisture impurity in the lamp then the coating on the glass will be black, due to the water cycle transporting tungsten from the filament to the glass.