Black | Red
While red/blue combination pencils are well-known, there are also pencils that have both black (graphite) and red leads. Here are a couple of old American ones, with a box:
The box describes what the pencils are for: Red lead for checking and special notations, black for shorthand and writing.
This type of pencil is more popular in Japan, judging from the many varieties –
I show both front and back because a common feature of Japanese pencils is that they have important information on opposite sides.
Note that all of these two-way pencils have black on the left and red on the right. But the one shown on the Shorthandy box is reversed!
Black/red combo mechanical pencils also exist –
The Autopoint at top is a famous example.
Fred's Pencils 
Fantastic. I especially love the old Yacht and the little Colleen with the eraser attachment. Have a few Colleens myself, but I’ve never seen that one.
May 21, 2011 at 4:22 pm
The shape of the hole in the eraser attachment is the profile of the Colleen logo.
May 24, 2011 at 11:31 pm
Cool. I have a basic question. I haven’t been collecting long, but a few of the older pencils I’ve picked up are pretty dingy, some may have even had mold at some point in the past. Have you found any safe, effective way to gently clean the barrels of vintage pencils?
May 25, 2011 at 1:34 am
I wipe pencils thoroughly with a damp rag. For the ferrule and eraser that’s about it, except perhaps scraping gunk and corrosion with a toothpick. To remove sticky stuff including old label reside, I use a product called “Goo Gone.” I only found it once at a store, but perhaps a similar product is available online.
May 25, 2011 at 8:56 am
If you can’t find “Goo Gone”, VM&P Naphtha should be easy to find at a hardware store, and it will remove label residue very well; you probably won’t want to soak the pencil, but dampen a cloth or paper towel and wipe. The naphtha may soften the paint, but if you are careful, you should have no problem. Also, denatured alcohol on a rag or paper towel is good for cleaning up pencil erasers. It won’t soften oxidized and hardened erasers, but will clean them.
June 23, 2011 at 1:34 pm
Sounds like something worth trying — in a well-ventilated place away from flames, I would say.
June 24, 2011 at 12:36 pm
Thanks. Goo Gone sells from their website, but for the moment I guess I’ll just stick with water.
May 26, 2011 at 8:18 pm
Hello, I just found your site via a link at Dave’s Mechanical Pencils.
I am thoroughly enjoying it!
Best wishes,
Stephen
June 10, 2011 at 4:34 am
I am honored!
June 10, 2011 at 9:56 am
I found your weblog via Dave’s Mechanical Pencils too.
Thank you for your effort – it is very amazing!
June 12, 2011 at 10:47 am