Coffee in conjunction to India ink can produce lovely art works.
Make strong coffee and when cold, brush the coffee on bond paper, water color paper or Strathmore board and apply several layers to build the shade of brown you desire.
The look will be one of water colors and the beauty of the coffee verses other edible liquids such as juices and wines is that it will leave neither pulp nor residue on your canvas.
When using paper for art work it might be wise to obtain acid free paper or museum board. These will keep the paper white for years to come and while there are different kinds of papers, alkaline paper can last 1000 years.
The bamboo artwork shown was not done on acid free paper so yellowing is occurring, but in this case it works.
Would you not rather tell a friend that your painting was done with gourmet coffee rather than water colors?