I would like to know this for a project im doing.

What substance should I draw in.. say on a piece of paper, so that blood would follow it?

 

So say that X substance, if I draw a line on the table/paper and drop a drop of blood onto that line, that blood should fill that line up without going over too much.

 

Thank you for the help, and ideas.

Filling that line just like water filling up a drain without spilling out? Wow, what a trick.

 

Anyway, i'm not sure whether my idea is workable or not. i suggest that the line is drawn by some organic solvents(with ionic property) such as carboxylic acid(vinegar), butter(if u want a solid), or probably alcohol.

Well the problem is that blood will stick to paper really really well. To get this to happen you'd likely have to coat all paper but the line in some hydrophobic substance.

 

Hmmm maybe you could take some wax paper and scrape off the wax where you want the blood to go.