Smoggy Posted April 7, 2016 Share Posted April 7, 2016 Warning: this may get a bit longwinded...... Today I have been cooking, well how hard can it be! It's only chemistry afterall, right? We have a vey nice cutlery set, bronze with hardwood scales, I like them, the wife not so much (that's her opinion of the cutlery not mine of her by the way) I digress, where was? I oh yes, I had been using the spoon from said in an aluminium alloy pan to make veg stock from various trimmings, once finished I emptied the pan and placed it, containing the spoon, in the slink with a dash of a 'lemon' scented propriatory washing up liquid, and hit the boil button on the kettle. I had more cooking to do and returned shortly after adding hot water to the pot and continued with the cooking. Not long after messing up more pans.knives etc I turn to pot washing, to get some of the task out of the way and ensure I had plenty of room in the sink for what ever it was I would inevitably burn! Enough of the background info, now to the interesting bit. On washing the spoon, I noticed that it had taken on a dark bronze patina on the tip where it stood in the residual soapy moisture. Me being me, the cooking was forgotten momentaraly while I investigated this patina recognising this may be something that could be made use off! A quick rub identified the stain as durable although not removable. So what happened? What casued this almost instant patina? Plenty of things could have caused or been party to causing a reation and I certainly have my suspiscions, Once I've cleaned the now hidden spoon (yes the wife is home from work) I'll be trying to repeat the process tomorrow and elliminate what ever variables I can identify. p.s. yes I burned the first batch of bechamel sauce......ain't teflon great Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted April 7, 2016 Share Posted April 7, 2016 Does the soap have citric acid in its makeup as well as its scent? Alan Quote Link to comment Share on other sites More sharing options...
Smoggy Posted April 7, 2016 Author Share Posted April 7, 2016 Alan, I didn't have my glasses on hand to cope with the extremely small print and things were starting to burn. As herself is currently milling about in the kitchen I'm staying out of the way......however, It almost certainly does have citric acid in some form and likely other possible 'accelerators'. I'll get a list up later. What surprised me was both the speed of the reaction and its efficacy! Quote Link to comment Share on other sites More sharing options...
JHCC Posted April 7, 2016 Share Posted April 7, 2016 Smoggy, what kind of bronze are we talking here? Quote Link to comment Share on other sites More sharing options...
Frosty Posted April 7, 2016 Share Posted April 7, 2016 The more noble (reactive) metal will plate the lesser if in an electrolyte. The electrolyte can be anything that makes water a conductor: detergent, salt, baking soda, ammonia, potato squeezins, lemon juice, sulfuric acid, etc. The more aggressive and or better the conductor the faster the replacement action. You can extract copper from soil, water, etc. by tossing scrap iron on or in it. Copper and tin are less reactive than aluminum so the electrolyte causes the al to go into solution and the reaction replaces it with bronze, copper, etc. If you want to speed it up use a more conductive electrolyte, hang the items out of direct contact and connect the two with a wire. Yes it's a battery and the electric currant is carrying metal ions from the anode to the cathode. (Do I have that backwards again?) Hooking up a DC current source will speed things and allow you to direct which goes where. This is pretty much straight out of the chemistry set Mother and Dad got me for my birthday when I was in elementary school. No my memory isn't really that good, the subject comes up often enough it's drummed it into my dented cabesa. Boats in salt water need help and get zincs bolted or welded to the hull to be dissolved saving the steel hull. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Smoggy Posted April 7, 2016 Author Share Posted April 7, 2016 I can only identify it as a "cutlery bronze" JHCC. I know there are some copper alloys that include both tin and zinc therefore transending the brass/bronze definition. However this from it's appearance and intended useage is a bronze rather than a brass. Quote Link to comment Share on other sites More sharing options...
Charlotte Posted April 7, 2016 Share Posted April 7, 2016 dish washing solutions are generally basic rather than acidic. How hard is the water you are using? Runs in my mind that "cutlery bronze' is a silicone alloy although not sure. Quote Link to comment Share on other sites More sharing options...
Smoggy Posted April 7, 2016 Author Share Posted April 7, 2016 How hard is the water? I could not answer that Charlotte, it's simply the same water I've been supplied wth my whole life. Other supplies are either harder, softer or the same! However, as there was no water per say inolved in the reaction other than residual veg stock I'd been making the question maybe should be how acid or otherwise was the stock! Silicone bronze alloy, you may well be correct, I have no way to know. Quote Link to comment Share on other sites More sharing options...
Frosty Posted April 8, 2016 Share Posted April 8, 2016 An electrolyte doesn't have to be acidic: salt or baking soda work just fine and there's no telling what all was in the veggies in the stock. Ever do the potato battery experiment? I don't believe potatoes are acidic though I think carrots are and cabbage is for sure, also high in sulfur. Yeah, that might be the source right there, sulfur compounds are pretty common in veggies so being acidic is probably automatic. I don't think you have a real mystery here just a little kitchen sink chemistry experiment going on. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
seldom (dick renker) Posted April 8, 2016 Share Posted April 8, 2016 have any tomatoes in there? Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted April 8, 2016 Share Posted April 8, 2016 It was my surprise when I noticed a rust stain on the handles of two adjacent "stainless" steel knives left on the draining board overnight which was my empirical introduction to the wacky world of oxidisation and corrosion...useful things kitchen sinks. Has any body experience of exciting things happening (apart from good food) around induction hobs? Smoggy, you are now duty bound to repeat the circumstances with a factor missing each time...no veg sauce residue, no lemony soap, no burned béchamel sauce, (hate to say this, but I have just been reading up about PFCs following a discussion about waterproofs on another forum I frequent...) no PFC fumes in the atmosphere from the hot Teflon... Alan Quote Link to comment Share on other sites More sharing options...
Smoggy Posted April 8, 2016 Author Share Posted April 8, 2016 I can ellimeate any PFC fumes, as that little incident happened after I noticed the staining Alan, systematic scientific investigations will be conducted today, Seldom, yes there was a small amount of tomato trimmings in the pot, and onion and ........... As an aside, I just had to do a little googling last night, and found the cutlery set on the web, and almost certainly the manufacturer.......Thailand, Bankok, so can now confirm it is bronze, what bronze, your guess is as good as mine! Lemony soap ingredients to follow. Quote Link to comment Share on other sites More sharing options...
mcostello Posted April 8, 2016 Share Posted April 8, 2016 We have a spoon that the plating has worn away. It makes food taste awful. Might give Yours a taste test. Quote Link to comment Share on other sites More sharing options...
Smoggy Posted April 8, 2016 Author Share Posted April 8, 2016 What was the plating? if it has a nickel underplating, and it's exposed I believe it may give a metalic taste and possibly not good for you. So you may not wish to use that. I'e not tested for taste abd don't intent to, I'll be executing a complete clean before use. The lemony liquid in question contains the following: Limonene, Benzoic acid, Citral, Citronellol, Geraniol. (I think that answers Alan question) I placed a small spot of the lemony liquid on a spoon and in isolation, there was no reaction, same spot incontact with the alluminium pot original result at original speed. Substituting plain lemon juice (acetic acid) also replicated the original reaction althuogh not a intensely. So it would seem, as I suspected, that both Alan and Frosty (and likely many others) have hit the nail on the head, an electrolytic reaction via the acetic acid. Still have no idea what either of the two alloys involved are other than bronze and aliminium. So looked for a few quantifiable samples to play with, as you do when your on a roll...... 99% alluminium, 1.5%, and 3% manganese and an old sample of bb2 (2% manganese/0.25% magnesium) which I understand is equivelent to 5251 ......all very much the same results. So if anyone wants to quickly add a patina to a piece of bronze work, there you go! (I'd avoid anything for culinary use to be safe) So now I have all this cutlery to clean, and worry about erroding away one of my favourate pans, I inherited from my Fathers and is likely older than I. The "product" in question, manufactured by the same company that produces luxury soap named after tanned hide goods of the empire also boasts.....sparklex TM, as an ingredient, (not the window cleaner available to Antipodeans) quoting " for sparkling clean dishes" Well if you have any Bronze platers and aluminium flatwear....DO NOT BELIEVE IT ! Quote Link to comment Share on other sites More sharing options...
yahoo2 Posted April 9, 2016 Share Posted April 9, 2016 All dissimilar metals have a potential electrical charge at their junction. Unfortunately Alessandro Volta has beaten you to the discovery by 222 years. However it took him 6 more years to build "the crown of cups" basically the first battery, then just a few weeks to have copper and zinc discs layered between damp cardboard soaked in salty water. Galvani was making frogs legs twitch with his metal strips and calling it animal electricity, got quite upset with Volta and his modern whackjob theory, it didn't end well for Galvani. Quote Link to comment Share on other sites More sharing options...
Dogsoldat Posted April 9, 2016 Share Posted April 9, 2016 On 4/7/2016 at 0:41 PM, Frosty said: The more noble (reactive) metal will plate the lesser if in an electrolyte. The electrolyte can be anything that makes water a conductor: detergent, salt, baking soda, ammonia, potato squeezins, lemon juice, sulfuric acid, etc. The more aggressive and or better the conductor the faster the replacement action. You can extract copper from soil, water, etc. by tossing scrap iron on or in it. Copper and tin are less reactive than aluminum so the electrolyte causes the al to go into solution and the reaction replaces it with bronze, copper, etc. If you want to speed it up use a more conductive electrolyte, hang the items out of direct contact and connect the two with a wire. Yes it's a battery and the electric currant is carrying metal ions from the anode to the cathode. (Do I have that backwards again?) Hooking up a DC current source will speed things and allow you to direct which goes where. This is pretty much straight out of the chemistry set Mother and Dad got me for my birthday when I was in elementary school. No my memory isn't really that good, the subject comes up often enough it's drummed it into my dented cabesa. Boats in salt water need help and get zincs bolted or welded to the hull to be dissolved saving the steel hull. Frosty The Lucky. Makes me want try a few experiments now. Big open pit copper mine just up the mountain and I know of an addit that has rather verdigris green rocks in a seam in it. Just need the snow to go away Still 3' up on top. Quote Link to comment Share on other sites More sharing options...
SLAG Posted April 9, 2016 Share Posted April 9, 2016 (edited) Just a little trivia for the gang. Lemon juice has citric acid as a major constituent. There is no vinegar in lemons and other citrus fruits. Vinegar is a 3% to 5% solution of acetic acid in water. Acetic acid is much stronger than citric acid. Very concentrated acetic acid is extremely corrosive. It's called glacial acetic acid. Acetic acid is commercially made from drinkable alcohol (ethanol). In the fermentation vats where alcohol is produced a bacterium called Chlostridium acetobutylicum converts ethanol to vinegar. That bug is called "mother of vinegar" SLAG. Edited April 9, 2016 by SLAG spelling and some extra information Quote Link to comment Share on other sites More sharing options...
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