Sometimes it can frustrating to sketch on location and have your material smear in your sketchbook. Many of us wish this wouldn't happen when are using charcoal or soft lead pencils, but often, it does. This smearing mess can ruin the sketches in our sketchbook. Sure, we could spray each drawing with a fixative, but then you have bring the fixative with you everywhere, and that's just not always feasible.
So what's the solution?
Well, one solution might be to try using a china marker for your sketches. I absolutely love china markers for quick sketches. China markers are really intended for use on nonporous surfaces like glass, but I have found that they create beautiful marks on paper that don't smear at all. China markers consist of a hard, waxy material that is rich in pigment. The consistency is similar to a strong crayon. The material is waterproof and some varieties can be sharpened by pulling a string and unwinding the wooden encasing material. The marks that are created are similar in nature to the marks found on traditional lithographs. You can easily create a variety of different marks by just tilting the marker to different angles. It is very easy to quickly build up a strong range of value. China markers are also inexpensive, usually less than a dollar. So, give it a shot, you may discover a new sketching medium.
The following video demonstrates a quick sketch with a china marker...