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Putting silver in the dishwasher

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Q. Some people aver that one should never, EVER put any silver into the dishwasher. Never. They quote good sources, too, like the Antique Roadshow people.

I'd like to disagree ... for plated silver they have a good point, it can discolour very quickly ... but PURE Silver doesn't, in my experience, show any signs of corrosion or discolouration whatsoever.

Why then does the plated silver sometimes ... but not always ... discolour pretty quickly even when in the open air? And surely there are different qualities of 'pure' silver depending on which country makes it.

If someone can educate me ... I'd be obliged ... and if they agree, ah, then I can point this out to my wife, too!

freeman newton portrait Freeman Newton
- White Rock, British Columbia, Canada
freeman newton died


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A. Freeman, you simply MUST invite me to dinner so we can both enjoy dining off your solid silver platters. Being of much more humble existence, I cannot offer any first hand experience of washing silver in dishwashers, but I have always been told it should never be done, especially with high phosphate dishwasher soaps. Furthermore, any abrasive soaps will scratch the surface of the silver and remove any fine engraving. There is, of course, another problem and that is if the silver comes into contact with another metal object, such as stainless steel (for us mere mortals) it can set up a galvanic couple, thereby causing a corrosive cell. This will certainly result in a blackening of the silver, unless, of course, you put your gold platters in there too. Then the silver will anodically corrode! Silver normally tarnishes in atmospheres where there are sulfide gases, but there also needs to be a certain relative humidity. I would expect that countries where silver does not readily tarnish are ones where the air is quite pure and the RH is low. Not all silver alloys do tarnish; one of the reasons for sterling silver(92.5% Silver)being introduced was to reduce the propensity of silver to tarnish. It contains about a fair amount of copper, often along with other elements and this helps protect the silver. Silver plate can be prone to tarnish by the silver being too thin and porous. This is because a galvanic couple can be set up between the base metal and the silver, with the silver almost invariably being the cathodic side, so it will be reducing species like sulphides. You may notice this when you drink your vintage wines form the pure silver goblets - the sulphites used to preserve wine can make the goblet go black.... Have a bottle of claret on me!

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK


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Washing in a dishwasher shouldn't cause any significant problem on silver, although you may see some dulling after repeated washing. A hand polishing now and then will take care of that. Sterling Silver in the USA is 92% silver, but in Europe there are grades ranging from 80% silver up to 99.9% They are usually identified as 800, 999, etc. The lower % silver stuff usually tarnishes more easily. Silver is actually fairly resistant to tarnishing, except for sulfur tarnishing. Rubber bands, eggs and other sources of sulfur including sulfur in the air from burning fossil fuels can blacken silver very quickly.

jeffrey holmes Jeffrey Holmes, CEF
- Spartanburg, South Carolina

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! Trevor, I ain't got none of dem gold tings wot you sez you eats off ... justa cupla grapefroot spoons wot goes inter the dishwasher religusly ... an' also one nife made by Rogers wich is over 40 yers old and still has a lotta silver onnit. An' our chalices ain't silver ... mugs is wot we use. China ones.

Yes, I agree with your hypothesis that plated, especially thinly plated objects do definitely corrode faster ... ditto for Sheffield plate, too, Mind you, brand new plated cutlery doesn't seem to be affected .... yet.

Thanks also to Jeffrey for his words of wisdom. You are very right! Hardly ANY effect at all using pure 92.5% Ag in the dishwasher... hardly notice any difference, either, if they get polished.

Thank heavens that we don't use Palladium, Platinum or Gold spoons then this would hasten the demise of lesser materials such as stainless.

Freeman Newton
- White Rock, British Columbia, Canada

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Q. We use our sterling silver place settings everyday and have always hand washed them. Several months ago we began to use our dishwasher since it has a special drawer which holds utensils flat but without touching each other.

I now notice that the silver is dulled in 2-3 days. I initially attributed this to using the wrong dishwasher tablets, but now understand that it is the entire mechanical dishwashing process that is to blame. I guess we will need to return to our tried and true method of hand washing!

Michael Segalla
- Paris, France


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A. The main reason that precious metals are precious is because you can make fine things out of them and they will still be fine things 4+ generations later barring unusual circumstances. Silver, gold and platinum are not very reactive metals (platinum one of the least reactive metals on the periodic table), and so any of those should be safe in the dishwasher. Unless, as the previous reader pointed out, you have a steel in there with it. In that case the more reactive (or less "noble" as we say in the trade) metals can actually plate out onto the silver, producing the discoloration that everyone is afraid of.

Usually your dish detergent will say something on it if it is not safe for use with silver, and most are fine. The detergents that are not safe with silver often employ reactive metal ions in their cleaning mechanisms, producing the discoloration in the same manner as mentioned before.

This is the perspective of yours truly, a chemist.

Craig Bettenhausen
- Baltimore, Maryland


April 13, 2009

Q. Help, I did put my silver-plated flatware in the dishwasher and some of the pieces are now spotted with dull gray or brown. My silver cleaning cloth doesn't clean them. Any ideas? I hope they aren't ruined forever!

Joan Heltsley
- Davenport, Florida


August 9, 2009

Q. I have the dark grey silver problem too. I started washing my silver several years ago in my dishwasher, but after moving this year to an area with a different water source and a different dishwasher, I am afraid I have ruined my silver within 3 months--help, please!

Connie Bonfy
- Wichita, Kansas



A. Hi, Joan. Hi, Connie. I'm reasonably confident that they are not ruined. Please see letter 4785 for a great way to clean silver.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

Electrolytic Cleaning Plate


April 21, 2012

Q. My new Zanussi dishwasher tarnishes the silver tableware whereas the old one left it bright silver. Why is this? I now have to polish it all when it comes out of the machine.

Gay Mould
- UK


April 22, 2012

A. Hi Gay. Might you have switched to a new detergent to suit the new machine? Was the old machine plastic and the new one stainless steel? Sorry, but I've never heard of a Zanussi dishwasher, so it isn't immediately obvious what difference you are pointing out. Thanks.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

June 26, 2012

Q. Hi,
I use silver plated cutlery on a daily basis, along with a few pieces of solid silver.

Per Martha Stewart, I put all this in my ASKO dishwashers (carefully separating from all other metal) in the US for years, with no noticeable effects. I used "ecological" detergents, but I don't know anything more about them than that.

Now I am in Australia, with an ASKO dishwasher, again. I am using ECOVER detergent. The silver is turning white (and blacker in the crevices) and losing its shine.

I called ASKO AU, they said they have received no other such complaints and have no recommendations other than separating silver from other metals.

I'm sure it has to do with the soap. All of the ecological detergents (I haven't examined the others) sold in Australia say clearly "don't put silver in the dishwasher", but I know that's not the whole story. It must be an ingredient? Unfortunately the detergents don't mention if they "employ reactive metal ions in their cleaning mechanisms", per Craig above.

Can we get more specific about this. And why is it such a mystery?

Thank you for your help,

VE

Violette Etoille
- Sydney, Australia

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