We are using a lot of fake blood on this shoot (as Penelope discovered). I found a few useful recipes off this site;
This is the one we've used the most (or something like it)
"Homemade Fake Blood
1 c. Karo Syrup
1 Tbsp Water
2 Tbsp Red Food Coloring
1 tsp Yellow Food Coloring
Mix together in a mixing bowl and you're done. Try adding blue or yellow for a different shade."
I've also used the chocolate one, and the gravy one looks easy and cheap. The Karo ones good but a little hard to find bulk Karo Syrup. It also washes out of peoples clothes very easily if you soak them in Napi-san.
We mix three different colours, red for humans and black and yellow for zombies as I didn't want to use green. We're in the bush, there's green everywhere, how much green do you want?
Funny enough, black and yellow, together make green.
I have also found that you need to store the stuff in the fridge or it grows mould after a week or so.