Brandon Trueblood Fights With Denny's Syrup! @Denny's in Pontoon Beach. Breakfast with Hammy

He's right.... and with the viscosity of the maple syrup, it needs a separate deep vent to increase the flow rate, by running air up into the bottom of the bottle.

One of the cleverest things I ever designed was an oil based hourglass...

Which varies with temperature - and the initial viscosity of the oil.

It's easy to make an calibrate one that is very accurate in a fixed temperature environment - especially with large tanks of oil... proportionally the bigger the tanks are, the easier it is to make it very accurate...

But an 8 hour timer or a 1 hour timer - if it's 5*C one day, and 40*C the next the oils viscosity varies tremendously as does the accuracy of the timing.

I guess the solution is a silicone based oil....