If you are in Special Effects, this is a great tip for you from one of our users; Johan Harnesk at Panorama SFX: Johan Harnesk is an SFX Supervisor and was asked to create a gruesome stabbing sequence – so he and his colleagues did this test scene, and you are invited to look behind the scene! In it, they affixed the self-adhesive nozzles under the clothes and fed them with stage blood (note the two tubings entering under the actor’s sweater at bottom, centre frame). Beware, as the scene looks quite violent, even if it is done with the “company crew”!
During actual filming, the dummy knife handle used here was switched for a stage knife with a retractable blade.
Note that the stage blood spreads quite realistically.
Get your nozzles here, if you want to rig something similar to what Johan’s crew did: https://airsquib.com/product/nozzles-5pcs/
Test clip provided courtesy of Johan Harnesk, Panorama SFX, Stockholm, Sweden. Find this great company at http://www.panoramasfx.se/