![]() I think that the screwdriver test would not be as reliable as a test where the fluids dripped through the same pinhole in the bottom of the sames shotglass-sized container that was filled to the brim with each. Mix viscosity (at 50 s -1 ) and fat destabilization were found to have a significant effect not only on drip-through rate, but also the induction time, final weight of the drip-through part, height. Many many moons ago, I worked in the darkroom of a printing house as a summer job, shooting artwork, making color separations, and making printing plates. In addition to the drip-through test, the shape of ice cream as it melts was recorded as height change to further investigate ice cream meltdown. ![]() Ink viscosity was a big deal to the pressmen, and they had a simple system with a metal ladle that had a small hole, and a stopwatch. ![]() They would dip the metal ladle into the ink, and time how long the ink took to run out of the hole. This might be a better low-tech viscosity testing set-up, as it will be a better test than allowing an unknown volume of oil to drip in each drop. N = the absolute viscosity of the ink/oil V = the speed of the withdrawal from the ink or oil T = the thickness of the (ink or oil) film on the withdrawn object (the screwdriver) The thickness of the film can be approximated by this equation (which mattered to printing plate makers, as it defined the amount of detail that could be printed with any specific ink): My "problem" with the screwdriver test is that both viscosity AND density come into play here, and there is no way to objectively measure the thickness of the oil film on the surface of the screwdriver as it is withdrawn.
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