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Ask HN: Are Dishwashing Machines Bullshit?
12 points by hypnoscripto 4 months ago | hide | past | favorite | 51 comments
When I was a kid, we had a dishwashing machine. It wasn't good enough that you could just put the dishes in after eating, you had to pre-clean them. I don't remember exactly how long it took, but it was at least 30 minutes.

As an adult, I've never owned one, and since becoming responsible enough to clean my dishes frequently, I've never seen the point in owning a dishwasher. I don't think I'm getting sick or anything from my hand washed dishes.

Is there real value in a dishwasher that I'm not understanding?




You don't have to pre-clean dishes. This video is a bit long-winded but gets the point across. https://www.youtube.com/watch?v=_rBO8neWw04

One person doing one person's worth of dishes is pretty manageable. Once you get more people involved, or if you're getting a lot of utensils dirty while making something fancy, it can be a whole different story. Also, I think they use less water than washing by hand, but again this depends on how many dishes you put in there at a time.


One point for dishwashers I haven't seen mentioned is that they get the dishes a lot cleaner than you ever could by hand, because very hot water. Gets the oils off much better than any amount of soap. For what it's worth.

First time I traveled to the US (I was 13) I thought there was something odd about the dishes... they felt strange. I told my host, I said "there seems to be a film of something that feels strange". He thought about it and said, "what you feel is the absence of something... the thin film of oil that you can't get off when you wash the dishes by hand, but the machine can." He was right.


Dishwasher detergent is a different animal from the liquid detergent people use for washing dishes.

It's not the only "game in town".

I once washed a load of dishes in a laundry tub filled with a pretty strong concentration of Mr. Clean floor cleaner in hot water.

They came out squeaky, sparkling clean, like out of a dishwasher, without any scrubbing.

(Why I did that is that the dishes fell victim top a drain backup: vertical stack clogged somewhere below my floor, causing other people's black, stinking drain water to start coming up in the kitchen sink, and it soiled a bunch of dishes that were in the sink. I had to resort to something strong and anti-bacterial to feel good about those dishes. I still put them through the dishwasher, too.)


I don't buy that. The scrubbing you do when hand washing must make up for the hotter water.


The specific combination of hotter water, rinse aid, and modern detergent mix (lipases, proteases, amylases, and surfactants) is actually able to remove certain chemicals that you couldn't otherwise remove via normal mechanical abrasion (at some point scrubbing harder with a harder abrasive will damage the dishes).

This is because the intermolecular bonds between certain food molecules (esp lipids like fats and oils) and the dish surfaces themselves can be remarkably strong. Additionally, it is quite possible for you to instantaneously remove molecules that are sticking due to intermolecular adhesive forces only for them to stick back on as you move said abrasive out of the way slightly.

The only real way you can actually remove such substances without mechanically damaging the dishes is to break down and/or dissolve them into the water so they don't restick to the surface.


Modern dishwashers are effective. You don’t need to rinse the plates before starting the dishwasher. (But of course you should remove large food particles first.)

However, for a single-person household it might not be worth it. For a household of more than two it’s definitely worth it.


What's the difference between "remove large food particles" and "pre-wash"?

If I can't take the dish off the dinner table and stick it into the machine, it means I'm pre-washing in some sense.


It means take the fork and push stuff into the trash. This isn’t rocket science here.


No, dishwashers are not bullshit. They wash more dishes with less total effort. Our family of four runs that thing at least once a day. Had washing does not scale. They are probably not worth it if you live alone and are diligent.


Living arrangements with restricted access to water (e.g. relying on RV or boat tanks or off-grid) may utilize a dishwasher to save water, and also save on energy to make hot water.


I doubt it. I have a dishwasher but don't use it. I wash and dry dishes by hand. It takes no more than 10 minutes to wash and dry two persons' dishes and cookware. I often cook and wash dishes at the same time!

But I've been washing and drying dishes since I was a child and my early years of conscripted dish washing were spent learning to optimize washing and drying procedures. So I'm very fast and efficient.

For a family of more than 4 persons, a dishwasher likely is handy though by no means a necessity. In the absence of a dishwashing machine, one person washed and a second dried.

As for the "pre-clean" phase - soak dishes and utensils in a sink or bowl of warm soapy dishwater for 5-10 minutes to loosen/remove most food residue. Then the dishwasher (wo/man or machine) will work properly.

But the true conundrum is this: in all my years of washing dishes both for myself and for commercial firms (college jobs as dishwasher) I have always washed knives - sharp knives. Yet I have never cut myself on a knife or a sharp utensil. I have learned that I can grab a handful of sharp knives from a soap-and-water filled sink blindly and quickly without fear of cutting my hand.

Something is going on that I don't understand: possibly the soap modifies surface tension around the blades and prevents them from penetrating my skin. This happens whether my hands are dry or soaked by hours of dish washing. Any ideas what is happening here?


You can firmly hold sharp objects by the sharp end relatively safely; it's the letting go that can be dangerous.

https://www.youtube.com/watch?v=vwuQPfvSSlo (Extreme example: At one point in time, people would sometimes hold sharp swords by blade -in the middle of a swordfight - and win!)

To cut something you need sharp object + cutting motion. No cutting motion means no effect.

I say relatively safe; because of course you're putting yourself in a position where you theoretically can get hurt if you accidentally loosen your grip.


That is different: he is pinching the sword with his hands. And FWIW it is far better to have your hand cut by a sword than to suffer a fatal wound.

In my situation I'm grasping a handful of utensils blindly (they're under soapy water), some which are knives. I can pull them up and sort them out w/o damage. Why?

The hand, and the combination of hand + eye, are remarkably facile. But in a suds-filled sink the eye is useless and the hand alone governs.


At 4:15 he also demonstrates full grip, then does a few full power murder strokes (mordhau) while holding the sword that way, and shows his uncut hands after.

Of course, we don't have to live quite that dangerously ;-)

If knives were to instantly cut on touch, blindly groping for them in the suds would be way too dangerous. (And I haven't really ever gotten cut that way either, so go figure)


I get it: you like swords. Well I've played with knives. I've grabbed knives and machetes and other sharp-edged tools. I know how to grab a blade and all that good stuff. There's plenty about swords and knives somewhere else on the WWW.

While washing dish utensils through my life I have observed something I thought was truly surprising and unexplained. Can't we focus on that?


Maaaybe I do like swords. And I mean, who wouldn't want to use that particular video as a reference sometime?

To be fair I honestly did think that that was the part that was mystifying you. Sorry about that.

I guess you're focusing more on the neural-network self-learning going on? Or... what's the interesting part to you?


No idea about the knives, but a huge non-US innovation is a drying rack. Wash the dishes, let them dry, put them away when you have time. If I had to dry them with a rag, I think my opinion would be different.


What do you mean by "non-US innovation"? I'm in the US and use a drying rack. I can't think of anyone I know in the US who doesn't use a drying rack.


People with dishwashers. Oh, wait... there's a drying rack inside the dishwasher!


I mean I am also a person with a dishwasher....


I don't! I wash, rinse and stack items so they are exposed to the air. They begin to dry right away.


Maybe different parts of the country? I’d never seen one until I left the US.


I would never go back to living without a dishwasher. Other than the labour savings, and the clean result dishwashers save a huge amount of water [0].

[0]: https://www.cnet.com/home/kitchen-and-household/how-much-wat...


Dishwasher saves us a lot of time, so it's pretty big value for us. We don't need to pre-wash any dishes, though.


Supposedly they (at least nowadays) use less water without pre-cleaning (at least nowadays) than doing it by hand. Don't care, don't have one, don't do much dishes anyways.


I live alone and it's great. I use it every two days. If you have something to dry you let it there so your kitchen is clean without things in the sink.

Would recommend.


Of course not. They save a lot of time if you know how to use them properly. Load it up tightly but without blocking the water spouts on the bottom and top, then load up detergent on BOTH slits (one big hole, and a smaller one for pre-wash), then warm up the water by opening the tap for a bit, and then press start with appropriate settings. It saves hours and hours of washing for me.


What's the issue with everyone saying that pre-cleaning is something effortful? Spending a few seconds to rinse a dish right after use saves you tons of effort later on. If you leave your lunch plates in the machine for a day before turning it on, chances are that even a decent dishwasher can't get all the gunk off. You'll end up scraping the rest with your fingers.

I don't get it why all the dishwasher ads tell you not to pre-clean your dishes at all. It is a very quick routine that really helps against permanent stains. It's much easier and faster to wash the dishes by hand if they were quickly rinsed immediately after use.


Rinsing the dishes before putting them in the dishwasher makes sense to me, too.

The dishwasher takes a small amount of (very hot) water and cycles that same water over everything many times. I don't really want a lot of sanitized (or not) food bits going over everything, or clogging the debris filter, thanks.

Fun fact, some 'dirt sensing' dishwashers sense dirt by using a resetable undersized fuse on the circulation pump. The more gunk in the water, the harder the pump works and the more it triggers the fuse. Count the number of activations to see how dirty the dishes are.


If you have left dishes in the machine for a day, what you do is run the machine without detergent first. Some may have a dedicated rinse cycle for that. This should be covered in the instruction manual.


I got one for my parents so they don't have to do dishes anymore. While my original thought was to free them from something they have been doing for years, I must say I am surprised with the performance.

Definitely no need to pre clean like others have pointed out (I believe the dishes are steamed/heated before the cleaning cycle so the heat takes care of the heavy grease and stuff).

Uses less water, about 10 liters/ 2.5 gallons per cycle.

May be I am taking a high ground here, but why do you want spend time doing dishes if you could afford a Dishwasher? Do something better?

Overall, I would say a Dishwasher would be useful even for a family of 2.


I like my dishwasher because:

1. It saves a huge amount of water.

2. It saves a lot of time for me.

That's basically it. If you feel you can spend the time without problems and water is not an issue in your area there is no need to get one.


Moms are often the ones who make you clean dishes before they can be cleaned. The thing is, you do have to clean the drain "lint screen" more if you don't prewash.

Dishwashers require a lot of manual labor even without prewashing. Like "flying cars," I dream of robot arms that can clear the table, clean the dishes, dry them, and put them away. How hard can it be? :X

I also thing hiring a maid and a cook are a good idea because I'm so lazy and busy.


A dish washing robot is the #1 robot people wish for


I moved from a place with a great dishwasher to one with not only a cheap one but also an OLD one. If I leave something bigger than 1/4in on the plate, it’s getting stuck in its drain until I wipe it out. It sucks hard.

Newer dishwashers can handle dirty plates no problem, cheese or no cheese and are much more efficient.

If this dishwasher had been my first experience I would’ve thought the same as you


The day I bought a dishwasher, I invited 8 people for breakfast, 8 people for lunch and 8 people for dinner.

You really don’t need to prewash anything...


Were they the same people? Not that it matters just curious.


No :-)


I guess you have a crockery set with eight plates!


I think it was the number of chairs :-)


If I lived alone I wouldn’t bother with a dishwasher, but for a family they are great. Biggest issue I find is unpacking them. There’s always stuff that hasn’t dried properly.

I think the ideal would be dual drawer dishwashers that you use alternately, leaving the clean dishes in one until you fill the other, so that the dishwashers become the cupboard. Do people do this?


I live alone and have a dishwasher. Put it on once a week and would not live without it - the dishes are spotless after washing. If it ever dies, I will replace it immediately. Only downside is having to keep the dishes 'under water' to prevent encrustation but this is only bothersome when other people are due to come around.


Mine has an option to pre wash that I use a couple of hours before washing when things have been in the washer for a couple of days.


The purpose of the original dishwasher was not to save time but prevent damage: https://spectrum.ieee.org/the-institute/ieee-history/this-so...


The modern ones definitely don't do that. I'm an unusually clumsy person and my dishwasher chips or breaks at least 20 dishes for every one that I break myself.


You must have a weird dishwasher or you put your dishes in weird positions because I've been using an 8 year old washer with my gf for last 2 years and it has never destroyed anything.


I put everything where its supposed to be. The dishwasher is probably pretty old though. I rent.

I've used several other ones over the last 20+ years and they have all been pretty mediocre in terms of cleaning dishes and not chipping them. Perhaps everywhere I've been has had substandard models. What model is yours?


We are in a process of moving from a place without one to a place that has one. I can't wait to be able to use it. Our kitchen is small and we go though a tremendous amount of plates, mugs,and saucepans each day. I do not want to stand by the sink for a few hours to do them all by hand,so to me,yes, It's worth it!


If you only have one or two people in a house, doing dishes isn't a big deal. If you had a family of five, yes.


It saves me from cleaning the dishes manually in a family of 4 with two young kids.

I'll use whatever I can to free myself up from a chore and spend more time with my family.


I went from not having a dishwasher to having one and it's fantastic.

I don't preclean anything, but I do follow the recommended loading procedure.




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