[sdiy] Weird tubular, grey (sometimes blue) resistors

[anthony]

In several thinsg I've taken apart over the years I have found these funky 
resistors that are tubular - like a hollow tube. They are usually grey and 
sometimes blue. The blue ones are often 1% and the grey ones often come out 
of cheap or old things and seem crappier. But I'm wondering what it is these 
resistors are made of? Is it another way to make carbon film resistors? I've 
seen capacitors like this too. It's usually easy to tell the difference 
since the resistors tend to have their values written out rather than 
color-coded. I wonder if there is any vintage mojo in these?


cheers,
aa