Just when you were about to ask, “What has the field of rheology done for me lately?” (apparently that’s the study of the flow of soft liquids), science has solved the conundrum of how to effortlessly pour ketchup. Anthony Stickland, an engineer in Australia who’s pretty boss at maximizing the flow of wastewater-treatment sludge, has turned his years of expertise to getting Heinz to slide out of the terrible glass bottle it comes in.
Ketchup’s problem, Stickland explains, is that it’s actually “one of the more complicated mixtures out there.” Simpler liquids like water and alcohol, or even oil, accelerate at a constant rate that depends on the speed the force is moving at when applied to them. Ketchup acts more like a solid — except for when it doesn’t, like when you smack the bottom of the bottle and watery goo rockets out all over your hot-dog bun.
To prevent this and the other problems marring the ketchup-pouring experience, Stickland says to just follow these easy steps:
1. Shake (with the lid on). The solid particles in ketchup will settle at the bottom, leaving tomato-y water up top, and remnants in the neck can dry out and plug the bottle up. Therefore, “Always start by giving the sauce a good shake,” he says.
2. Turn the bottle upside down. “If there’s not much left in the bottle, you may need a strong whack to dislodge tomato sauce from the bottom,” he says. “Turn the bottle upside down (still with the lid on) and thrust downward at high speeds, accelerating both the ketchup and the bottle. Swiftly stopping the bottle should slump the sauce into the neck.”
3. Tilt and pour. It’s now time to pour. Remove the lid, and start tilting the bottle. “There needs to be some force to overcome the yield stress,” Stickland explains, “but not too much.” Force should vary according to how much ketchup is left in the bottle; if it doesn’t move once inverted, there isn’t enough sauce left to induce flow. The trick is finding the “sweet spot” of force — to get the sauce moving without splattering: “Start by pointing the open end of the bottle toward your food at an angle of around 45 degrees, with one hand around the bottle neck and the other delivering gentle but firm taps on the bottom of the bottle. Increase the force of the taps until you balance the force applied with the mechanical strength of the sauce, in order to get it to flow.”
He tells the New York Times jabbing a knife up into the bottle can also help, though that’s widely understood to be a great way to start a ketchup avalanche. He points out it’s okay to just buy the stuff in the damn squeeze bottle, too — that’s actually his personal fix.