can you tell the diff tween metal film and carbon film on sight?

Is there any way to know by looking at these grab bag resistors I got from Futurlec if they're metal film or carbon film?

I just installed a couple 1M resistors in a RangeMaster before reading this:

I also added 1M resistors to the input and output to prevent popping with my true bypass arrangement. As RG said in his article about the RangeMaster, you REALLY need to use 1% metal-film resistors for this circuit because they are less prone to noise...and this thing will amplify hiss and hum and anything else that happens to find its way in.

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Should I just assume they're carbon film and replace them now - even before I've finished.
That's the way I'm leaning at the moment. (Just fired up the soldering iron.)

If they are 1% tolerance they are most likely metal film.  I would be surprised if anyone were selling much 1% carbon film these days---they would be antiques---but I guess it depends on the grabbag.

5% tolerance 1/4W and 1/8W parts on the other hand are most likely carbon film.  And sufficiently high value parts are also likely so, but this would be over 1M most of the time.

As far as judging by appearance, it's a little like the one judge's remarks about pornography: he couldn't explain what he used as a criterion, but he knew it when he saw it.

look in "The Art of Electronics" in the resistor section about resistor noise carbon film and metal film etc it is interesting.

see pg 432

if it has a brown body and old school paint for color bands, then it is probably non metal, but not always.

Gus said:

look in "The Art of Electronics" in the resistor section about resistor noise carbon film and metal film etc it is interesting.

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Gus, had a look and they are closer than I thought to each other !!
I hear that it matters more as the value of the resistor increases -> 1M and up ... right ?

MM.

CJ said:

if it has a brown body and old school paint for color bands, then it is probably non metal, but not always.

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They are BROWN.
Looking at Futurlec's web site, they show "carbon film" with this pic: and metal film with this pic:

How insane am I?
I have a bin containing 50 1M metal film resistors from Mouser, and 5 or 6 brown ones I got from the grab bag - and which ones do I use? the brown ones. What is wrong with me? 

Also I measured them before installing. More evidence of my neurosis. They were quite a ways off from 1M.

Of course I desoldered and replaced them before even waiting for a response. Easier to fix it now than later.
The blue resistors measured 998. So I guess there's my answer. Thanks everybody.

seavote said:

see pg 432

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Thanks I will!

by brown, i mean the old dark brown, like you get when you buy a 2 watt carbon comp from 1950.

CJ said:

by brown, i mean the old dark brown, like you get when you buy a 2 watt carbon comp from 1950.

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Ah right. BROWN, not beige.

Maybe the carbon film warning be overblown. Did not the original RangeMaster have carbon comp?
Nobody bitched about those.