When is the white deposit left by dishwasher, wash or rinse cycle?

[Stephen Tashiro]

When phosphate free dishwashing detergents are used in a dishwasher where the water is hard, a white deposit is often left on the dishes. Is the deposit left during the wash cycle or the rinse cycle?

Logic would say that it must be left during the wash cycle since no detergent (with or without phosphate) would be present in the rinse cycle. The rinse cycle behavior wouldn't be better or worse if the detergent did have phosphates. Howver, logic is poor tool for analyzing reality. In which cycle is the white deposit actually left?

[Jim Koepke]

Have you tried different brands of soap in your dishwasher?

There is also a rinse solution that some dishwashers have an ability to use.

Many years ago one of the major dishwashing formulas would actually etch glass. I hope they have changed their formula, but could that be what you are seeing?

Are you using the phosphate free products because you are on a septic system?

If you are using well water, talk to an expert about a water softening system.

jtk

[Ron Conlon]

I'm dealing with this as well. Our regular brand of dishwasing detergent suddenly started leaving tons of residue. I think they changed their formula. Then we got a new water softener after the old one died. I'm still experimenting to find the optimal mix of water softness and detergent.
Also, I started using distilled white vinegar in the rinse compartment- it works great. And at $1 a gallon it sure beats $4 for a few ounces or rinse aid.
Lastly, if logic is not helping to analyze reality, then logically, you should challenge some of your assumptions. :)

[Brett Robson]

I heard a discussion of this topic on the radio a few weeks ago. From what I heard, Procter and Gamble, the maker of the majority of brands of detergent, switched to a near zero phosphate formula to comply with new environmental laws.

Here's an article (http://www.nytimes.com/2010/09/19/science/earth/19clean.html) that explains the story.

I heard in the discussion mention of a variety of additives one can add to their detergent to make up for the missing phosphates. If you don't want to watch your dishwasher run in order to catch it at the start of the rinse cycle to add vinegar or whatnot, you can buy some
trisodium phosphate (http://www.amazon.com/Savogran-10621-Trisodium-Phosphate-TSP/dp/B0001GOGQW) and add a half-teaspoon to the detergent and forget about it!

[Stephen Tashiro]

I'm familiar with the cause and remedies for the white deposit. My question is much simpler than "What is a remedy?" . To repeat, I 'm asking "When is the white deposit left? Is it during the wash cycle or during the rinse cycle?". I've read articles about the problem and haven't found one that explains this.

I think it's a good question. For example, when I wash dishes by hand, in the same water as used by the dishwasher, I don't get the white deposit, even though I don't dry the dishes by wiping them off. My dish washing detergent for hand washing says "phosphate free". So why no white deposit?

The dishwasher probably uses much hotter water than hand washing. But one of the recommendations for getting rid of the deposit is to turn up your hot water temperature. If hotter water helps, why doesn't hand washing dishes leave the white deposit?

[Brett Robson]

Excerpt from the article I linked: "...phosphates help prevent dishes from spotting in the wash cycle..."

As to why hand washing does not produce the same spots, I think your guess would be as good as mine!

[Stephen Tashiro]

The article also says:

So Mrs. Jones now rinses them all by hand after the wash cycle, trying to economize on water so that her rinsing can match the dishwasher’s efficiency.

Why would Mrs. Jones rinse her dishes by hand to "match the dishwasher's efficiency" unless it was the rinsing by the dishwasher that left the white deposit?

[Stephen Tashiro]

Also, I started using distilled white vinegar in the rinse compartment

Vinegar can be corrosive. Do you notice any effect on the metal parts of the washing compartment?

I wonder if the vinegar works by preventing the white deposits or by dissolving the white deposits that are left by the wash cycle.

[Jim Koepke]

I'm familiar with the cause and remedies for the white deposit. My question is much simpler than "What is a remedy?" . To repeat, I 'm asking "When is the white deposit left? Is it during the wash cycle or during the rinse cycle?". I've read articles about the problem and haven't found one that explains this.

Maybe you will have to find this answer by doing your own experiment.

Stop the dishwasher before the rinse cycle if you can. Check to make sure there isn't any soap component left in the soap compartment. The reason this is mentioned is the soap we use has multiple components that if my guess is correct dissolve at different times during the cycle.

If there is anything left of the soap, remove it. Also remove some of the glassware or a few of any item that has shown the white deposit from the machine.

Put the machine back in service. Let some of the items removed air dry. Rinse some of the items removed.

When the dishwasher has completed its cycle, you may be able to discern an answer and come back and tell us all what you discovered.

jtk

[Stephen Tashiro]

Maybe you will have to find this answer by doing your own experiment.


What's the world coming to when I have to answer my own questions! :)

Experiments are a good idea. Before I do this, who can tell me about the water level in a dishwasher. If I miscalculate and open the door before the water has been pumped out, will the water level be low enough so it doesn't spill out on the floor?

[Jeff Bratt]

Whenever I've opened my dishwasher door (at least 3 different models), even in the middle of a wash cycle, the inside water level is always below the door sill. Yours could be different, but it should be safe to try it...

[Stephen Tashiro]

Experiments:

I cleaned the white deposit off some glass bowls and cups with vinegar and a copper scrub pad. Then I washed them by hand and rinsed them by hand. I put these in the top rack of the dishwasher. I put some 9 clean ceramic bowls that were washed by hand in the lower rack.

I ran the dishwasher through the rinse cycle and then opened the door. There was no white deposit on anything. I let the dishes air dry inside the dishwasher. (This is how I normally dry dishes.) There was no white deposit to speak of. There were only a few light white smears like I get when I do hand washing.

I put Finish brand dish washing detergent in the dishwasher and ran these same dishes through a complete wash, which consists of two wash cycles. When the machine emptied, I opened the door and examined the dishes. There was no white deposit. I took one glass bowl out and put it in a rack to air dry. I closed the door and ran the dishes through the rinse cycle. I let them air dry. There was no white deposit. There was no white deposit on the bowl that I took out earlier.


I replaced the 9 ceramic bowls with some dirty dishes and put in some dirty silverware in the silverware basket. I put Finish brand detergent in again and ran the dishes through the complete wash and rinse cycle. There was no white deposit.

This wasn't a big load of dirty dishes and they weren't extremely dirty. Perhaps the white deposit only forms when I have a load of dishes that don't get completely clean during the wash cycle.

[Ron Conlon]

Hmmm... Sounds like Heisenberg's Uncertainty Principle has come into play here. Do you have access to a subatomic particle accelerator?

[Stephen Tashiro]

Hmmm... Sounds like Heisenberg's Uncertainty Principle has come into play here. Do you have access to a subatomic particle accelerator?

No, and I don't have a water softener either.

You didn't tell me if the vinegar was corroding your dishwasher.

[Ron Conlon]

It's not. Ascetic acid is pretty mild, and it is further diluted with the rinse water.