Martin said: "curious as to what causes one machine to rinse better than another...." and then listed a number of good reasons why some machines rinse better than others.
Another reason for poor rinses are how the water spray enters the tub -- for machines designed to do an eco-spray rinse, the water is often directed in a very wide fan-like pattern and midway between the agitator and the clothes, so the spray fully distributes and rinses equally well no matter where your clothes are.
The "original" Amana/SpeedQueen from the 90's didn't do that -- it had a "self-cleaning" "filter" a la rim-flo (like the Hotpoint), but unlike the Hotpoint washers, the water jet would fall inside the filter and mostly be directed outside the basket with just a tiny bit passing thru the filter and reaching the inside of the basket. Of course, once the spinning started, the piddling amount of water that actually was directed to inside the basket would be deflected by the air and the spinning motion and just rinse the top few inches of clothing.
In fact, an experiment I would frequently run to show friends where the water hit, is to fill the washer basket with a load of towels, start the machine at the spin rinse portion, and turn it off before it starts filling for the deep rinse. See which towels are dry and which ones are damp. Some machines will only spray rinse the lower few inches of clothing, some only the top few inches. Ideally, all the towels would be equally damp if the spray rinse was effective.
Another test, a bit more fair, is to wash a load of towels with hot water, let the cycle progress a bit after the spin rinse but stop it before it starts filling for the deep rinse. See which towels are still hot (very little rinsing), which towels are warm or cold (better rinsing). The rinsing pattern for this test is often different from the first one because of the way the clothes settle when the machine drains (neutral or spin), and the combination of detergent and water alters a bit how the rinse water filters thru the clothes on the way to the basket walls.
A fascinating test, which most places do not have the lab equipment to do, but you can often see it in Universities that study fluid dynamics -- the washer is either fed with washable dye for the wash and then the spin rinse is regular water or the reverse, spin rinse with tinted water to see the dye distribution on the clothes.
In any case, seeing is believing -- toploaders, as a class, do not rinse well, and the ones that do have a much better spray rinse than the others. Frontloaders dilute the dye solution out of the clothes much faster and with less water. The key here is not exactly how you agitate the load (top vs. front-loader), but the fact that if you saturate the clothes and then drain or spin them and do that multiple times you dilute and get rid of the "wash solution" (or dye, in this case) faster than only one or even two deep rinses. This is the reason that a good spin rinse and a deep rinse were enough for older toploaders, but most of them made in recent times went straight from wash to spin to deep rinse, which is not ideal. You want to remove way more detergent before the fabric softener or vinegar hits the clothes in the rinse. Toploaders with a decent spray rinse (recirculated, and several distinct spray rinses which drain and repeat with fresh water) can rinse very effectively too, but most toploaders did not do that and I haven't keep current with the market to know if the newer ones have changed. But the system is pretty old, Fisher&Paykel washers did this I think 20 years ago, there were a few models like the WP Resource Saver and Calypso, and I think, if I got the descriptions right, maybe the newer Speed Queens are doing something similar? Not sure.
Cheers,
-- Paulo.
