Besides the Derwent watersoluble pencils which I reviewed earlier, Derwent has another water-soluble graphite pencil in a brand called Graphitone. Those in the middle of the photo above are the Graphitone.
I like the watersoluble sketching pencils. I like the Graphitone even more.
The Graphitone is actually a stick of pure artist quality water-soluble graphite. It's not technically a pencil because there's no wood. There's a protective wrap that you can peel away easily to expose more graphite. I expect it to last a while so it's really economical.
These are really great at creating washes, and layers of washes.
You can use them like normal pencils, hatching over an area before applying water to create a wash. Unfortunately, they don't dissolve totally so hatch marks can sometimes still be seen.
My preferred usage method is to use a waterbrush to brush on its tip before applying onto paper. The graphite would dissolve and get onto the brush and can be applied onto paper that way. You can also brush it across the tip hard to create splatters. The 2B version of Graphitone is way more soluble than the pencil version.
Once dry, the graphite is amazingly permanent. You can apply another wash on top without smearing the one beneath. You can run your figure over and it won't smear either. Since they are that permanent, it's difficult to remove mistakes if you get a wash wrong. Their lightfast rating is 8, which is around 200 years.
The sticks are available in 4 hardness, 2B, 4B, 6B and 8B. Tones can be created by either using more graphite, or by layering washes. I can create 3 tones easily using the 2B stick. These Graphitone are perfect for practicing tones.
The Graphitone are available separately, and also sold in packs, sometimes together with other pencils (shown below). I bought mine in a Fine Art Pencils pack which consist of watersoluble sketching pencils (2B, 4B, 6B), Graphitone (2B, 6B) and a small brush.
Here's another pack which features other items:
After I finish using up my watersoluble pencils, I'll be getting Graphitone from now onwards, eventually all the 4 hardness.
I really enjoy using them.
Below are some sketches I did with them.