Much like one might have idle shower thoughts, I had an idle sink thought while washing a peanut butter jar before putting it in the recycling. My technique was to fill the jar about half full with hot soapy water and then shake it violently to make a saturated peanut butter emulsion, then repeat as many times as needed to get the jar ‘clean enough’.
It seemed like I instinctively filled the jar half full or less, because it feels like banging the slug of water back and forth with some ‘fetch’ would do a better job than, say, filling it 95% full and not getting so much mechanical impact, even though more water can dissolve more peanut butter. It got me thinking, though, about what the parameters might be to optimize the removal of goo from inside a container by agitation with a solvent.
-Are higher shaking frequencies better? Is it better to have more water per cycle or less? Should I fill the peanut butter jar to the top and swirl it gently, or put in a half-cup of water and shake the bejesus out of it? I suppose I could fill it full and hit it with ultrasound, but I can’t shake that fast. I guess that I want to minimize the time to clean, not necessarily the amount of water used, but then again I don’t want to just run water into an open container until it’s totally sluiced out.
Surely this is a class of problem that industrial process engineers have worked on? Does it have a name?
you could have it a quarter full and add a spoon of gravel.
(You can buy beads for cleaning glasses/vases which work on the same principle.)
ETA like this.
I’ve also wondered about this. There has to be an optimum amount of water between 100% and 0% at which the maximum amount of scrubbing force happens. I’ve also wondered if the speed of agitation affects the optimum amount of water. For instance, perhaps a slow agitation is best with a lot of water and a fast agitation is best with less? Anyone have a variable speed paint shaker and some time to do some experiments?
Back when we recycled I pondered this conundrum with every peanut butter jar. And mayo jar and … but PB was the thing I/we ate the most of. I made a few informal experiments, but took no real measurements, made no notes, and have no real conclusions.
I know I have no FQ answers. In terms of WAGs …
In a handwavy sense, shaking frequency and amplitude together amount to total energy imparted to the water. Which ought to be pretty close to a measure of PB removal rate. Once you cross whatever threshold of effort is required to overcome the mechanical strength of PB and remove any at all. Abrasives (large or small) will improve the energy coupling and reduce both the threshold to start getting results, and the incremental effectiveness per incremental effort applied.
As PB is removed and emulsified the amount of free detergent available declines. When reduces the effectiveness of further PB emulsification. But too much detergent also makes more suds which are just a mechanical obstacle to good shaking performance.
Heat really softens PB and renders it less sticky. If the only source of heat is the temperature of the water first added, more water will be helpful, and less water unhelpful. If the whole process could be done in a constant temperature oven this factor could be removed from the calcs.
An interesting problem to be sure. I hope we do have a pro who can weigh in at least a bit.
The optimal strategy will depend on the solubility of the goo.
Most of the stuff you are seeking to remove is oily/fatty ie less soluble.
So the mechanical forces applied are more important.
Default, about 1/3rd container with hot water plus a small amount of detergent with vigorous agitation. An abrasive agent (sand/salt/beads) multiplies the impact of the agitation.
As goo solubility decreases, increase the mechanical force ie less water, more agitation, more abrasion. Physically remove as much of the goo as feasible before hydration.
As goo solubility increases, use more water (hotter is rarely a disadvantage), less detergent and less vigor (though again is rarely a disadvantage).
I would say less water, but more passes. It’s better to fill to 50% twice than once to 100%, and better yet to fill to 10% ten times.
It’s not always worth optimizing water use this way (though it can be, say if you’re camping), but with other solvents it can be a decent savings. When rinsing with isopropanol, I go for a large number of passes.
I did this with a mayo jar just a few hours ago. I usually fill it a bit less than half full, and shake so the water hits all the parts. I don’t even put soap in, since purely mechanical action works fine.
Emptier than that I don’t think you’d get pressure against it, more full and you won;t have the distance in air over which the water can accelerate to hit the sides of the jar.
It seems like there may be two classes of problems. One is where there is some kind of goo inside the container that gets dissolved in the water. Another class of problem is where the water is just acting as an abrasive to rub something off of the container, such as a paint dot. It might be simpler to initially consider just the “water as an abrasive” problem to determine the optimum agitation speed and water level combination which allows the water to provide the maximum amount of abrasion (e.g. remove a paint dot). The goo aspect is adding another layer of complexity since goo percentage in the water will affect how clean the container will get.
If it’s soluble, then you can just fill up the jar and let it sit for a little while. Possibly multiple passes, if there’s too much goo, but still no shaking required.
Ah. Goo in a jar. The dishwasher persons worst enemy.
Yes. Half full is best. Hot hot water is best. Soap doesn’t matter til the last shaker/scrubber action.
Dawn dish liquid will dissolve peanut butter magically. I promise. It works on hair too. Just gets that peanut butter right out.
I do know from my informal experiments that filling a PB jar to the brim with very hot water, no soap, and leaving it be for couple hours will result in almost all the PB softening and falling off. And what’s left has no adhesion to the glass and comes loose with just a gentle swirl.
So even something quite fatty and gooey is susceptible to water’s magic.
And if we’re optimizing for effort this is the winner. OTH, if we’re optimizing for keeping impatient people happy (i.e. me), the shaking with soap and being done in 3 or 4 minutes is somehow more satisfying.
I will do the shaking thing to clean most containers, but not peanut butter ( Skippy, if it matters). Its just not worth the time, water, and detergent. Dont like putting it in the DW, and dont want any sticky PB going down my drain only to cling to my pipes.
Frankly, how much water and trouble do you need to spend to clean a peanut butter jar? And it may not be necessary for the jar to spotless. As this New York Times article says, even with a little peanut butter, the jar may still be recyclable.
The last is an ingenious and water-saving method, but it doesn’t work for those of us with cats or short-nosed dogs.
I live in a household of slobs, so we have no problem filling jars and leaving them to soak overnight. I usually do just that, then, if the contents were greasy, dump it out and drip a little Dawn in with about a quarter of a jar of hot water. Shaking that up usually cleans it the rest of the way.
Now, if the top rack of the dishwasher isn’t full, sometimes I get even lazier and just put containers in there to get residue out.
My peanut butter comes in plastic jars. I wouldn’t think they are recyclable. Not privy to that info.
I used to save the glass ones for small objects. Still have dozens in use around here.
After you wash the plastic ones and use them they get sticky on the outside. Not serviceable anymore in my world. They go in the burn barrel after that.
I don’t have a dog either, but I do have a spatula. I can usually get enough additional PB out for another sandwich. After that, I take a piece of bread and tear off one piece at a time, putting it on the end of a fork to scrape off any remaining bits in the corners. Fully clean jar, no water!
Notwithstanding all of this, I have also had these same idle-sink-thoughts as I vigorously shake containers I am trying to clean. There’s probably a PhD thesis in this somewhere!
(For example, with jam jars I shake with milk instead of water and drink the “smoothie” that results. Yummy!)
