It’s Just Cool: Traditional Japanese Carpenter’s Line
By Benjamen Johnson On April 11, 2008 · 3 Comments · In Hand Tools, It's Just Cool, Marking, Unusual Tools

These beautifully crafted Japanese Sumitsubo carpenter’s lines are similar to the familiar chalk line, only they use ink grains dissolved in water instead of chalk. The ink leaves a much finer line.
You prepare the Sumitsubo by soaking cotton wadding in an ink solution and drawing the silk line through the soaked cotton. Then you tension the line and snap it, like a normal chalk line.
The plainer but still elegant model runs about $75 to $100. The more elaborately carved “Drinking Dragon” runs more in the $300 price range.
The Sumitsubo [Dieter Schmid]
Sumitsubo Set [Japan Woodworker]
Something similar … Japanese marking “knives”
http://thejapanwoodworker.com/dept.asp?s=JapanWoodworker&dept_id=12995
Do you then spend days with your fingertips stained black? I think I’ll stick to chalk, or a marking knife if I need a finer line.
Tajima makes a modern version.
http://www.tajimatool.com/shopping/2inkrite.htm