I found another Electrofar tube in a thrift shop. This time, it's a 20w one. The etch is almost gone, but it says 'White' and 'Made in Romania'. I can't recognize any factory markings. Color temperature is close to 4000k, i think it's the same as 'cool white' 640. To the eye it appears ever so slightly warmer, but it is almost completely worn out.
It has brass end caps, with little divets/dimples in the crimp.
The phosphor coating has a LOT of inpurities.

In the fixture in the attachment, the top one is the Electrofar, the bottom one a Narva (1982) which is also very heavily worn. Socialist lighting at its finest! Well, except for the ballast and fixture, which are Philips HF warm start.
Together, they create a very sickly greenish atmosphere.

No one has any clue about the age of these things?

I sure don't, but I may look into it a bit today...