Dishwasher and a white powder residue

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I put a knife at bottom of the dish washer, and this was the result after 2 hour cleaning and drying time (just rarely though). What is the white powder?

Is it the salt? The soap? scales from hard water? Or dried rinse aid?

powder on knife.jpg
I recently acquired dish washer. It seemed to clean the dishes and utensils well. I didn't get it decades ago because I thought it was not that efficient.

When we manually wash dishes and utensils. We used force in our hands towards the surfaces of them. For dish washer, they just use tiny rotating spray. Can the force of each spray be equal to that of our hands? How do you compute for the forces? I just want to have ideas. Thank you.
 
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I don't think there could be powder like that if the machine is working properly.
Was it with the edge pointing up?
 
Keith_McClary said:
I don't think there could be powder like that if the machine is working properly.
Was it with the edge pointing up?

Its flat at bottom. Afterwards it put pointing up. But what's the powder?
 
From past experience (which PF says has no validity) and manufacturers manuals, that is soap build-up, a common occurrence.

The fix is to run a cycle or two with a cup full of vinegar in the bottom rack.
 
Tom.G said:
From past experience (which PF says has no validity) and manufacturers manuals, that is soap build-up, a common occurrence.

The fix is to run a cycle or two with a cup full of vinegar in the bottom rack.

The disc washer is new, just a week old. Soap build-up in the knife which was just put can occur?
 
jake jot said:
What is the white powder?
Probably soap. What does it taste like?
It seems the white buildup was inside a circle made by contact with the lip of a cup. It might be that the area was not washed because the cup sheltered the knife from the water spray. Soap powder could have been trapped on the blade.

jake jot said:
We used force in our hands towards the surfaces of them.
The force needed by the dishwasher is less than when you wash dishes by hand since the dishwasher has more time to let the hot water soften the remaining food.
 
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Baluncore said:
Probably soap. What does it taste like?
It seems the white buildup was inside a circle made by contact with the lip of a cup. It might be that the area was not washed because the cup sheltered the knife from the water spray. Soap powder could have been trapped on the blade.

Great forensics analysis! You may be right.

Anyway. Since I just owned one. When the detergent bar fell to the bottom, how does it get into the upper spray fan? Is there pump of some kind for water at bottom to recycle above?

dish washer detergent.jpg


I saw the insides of it at youtube

Inside the Dishwasher - Regular Soap vs. Dishwasher Detergents [4K] - YouTube

If the fan got stuck by a utensil, would the fan blades break or is the fan run by some kind of water pressure? what's the mechanical impeller at center?

Should have owned a dish washer 20 years ago. I wouldn't have bought one if my cousin didn't get one. I know of no other people using it.
 
jake jot said:
If the fan got stuck by a utensil, would the fan blades break or is the fan run by some kind of water pressure?
It's like a lawn sprinkler (but slow).
There is a pump at the bottom.