What makes glyphosate drain like in this video?
June 5, 2021 12:28 PM   Subscribe

There's a video on Reddit of glysophate draining in a peculiar way. What's at play here? I don't think it's non-Newtonian in this state, is it?
posted by metabaroque to Grab Bag (4 answers total) 2 users marked this as a favorite
Camera frame rate interacting with flow patterns? See, for example, what you can do with water.
posted by hanov3r at 12:42 PM on June 5 [7 favorites]

This liquid draining from a tank has a pattern to its flow that repeats in a very regular fashion (it oscillates). As hanov3r says, what we see in the clip is mostly a result of the video frame rate closely — but not exactly — matching the frequency at which this pattern oscillates (if you wanted to get technical, you could say that the frame rate is nearly a multiple of the oscillation frequency). Because the frame rate is close to, but doesn't exactly match, the oscillation frequency, the flow pattern appears to move slowly. If the frame rate exactly matched the oscillation frequency the liquid would look like it was frozen.

Shutter speed, which is the amount of time that each frame of video is exposed, also plays a role. Since it’s very sunny the shutter speed is probably fairly high (on smartphones this isn't a setting most people can control), which minimizes the amount of motion blur in each frame, giving a sharp-edged appearance to the turbulence in the liquid.
posted by theory at 4:15 PM on June 5 [3 favorites]

Here is another example of what can happen when the camera's shutter speed syncs up with the thing that it's filming. In this case, it's a helicopter.
posted by Hatashran at 6:31 PM on June 5 [2 favorites]

Best answer: Thing is (if that's a glyphosate mix), glyphosate (which usually has an oil base by the way, so naturally is a little viscous) is always mixed with water, for large quantities like this, dilution is as much as ~200 times.

Also there's usually other chemicals in the tank; pH balancers, (2-3%)industrial veg. oil (for droplet size control), anti-foamers, stickers/spreaders (to control leaf action)...So the final mix can be quite viscous.

Also (apart from something weird with the frame-rate) this is a normal effect from not allowing enough air in the top, so the fluid glugs out. Can collapse a tank that way.

* I used to do this for a living.
posted by unearthed at 7:53 PM on June 5 [3 favorites]

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