how can we chemically make silver articles black or tarnish them?
953754
Of course, it is a chemical reaction that causes ths to happen naturally.\n\nExpose the silver article to sulphur. SO2 would do the job most admiarably. Dipping it in egg yolk too - it is the sulphur that does the job.
981036
Contains nothing but the white paper. The black to gray areas contain silver metal. The silver is present as black particles rather than the "silver" appearing metal on flatware, jewelrey, and mirror backs. After the black to gray areas are developed by reducing silver compounds to metal, the print is "washed" with sodium thiosulfate, Na2S2O3, to remove excess silver.
391994
Each color is obtained by using a different chemical or mixture of chemicals.  Many dyes and pigments involve heavy metal compounds, such as iron and copper.  For instance, iron oxide (rust) is used in some paints.  The color of a particular compound is determined by the frequencies of light it absorbs.
957199
If you are doing it in a laboratory setting, you can mix it with carbon and reduce it to the metal. You will need high temperatures, though.
386803
I can't answer your question with absolute certainty, I apologise, but may have something to point you in the right direction...\nThere used to be a show on HGTV called Modern Masters- there was a metal artist on there once, the cut 1/2 inch wide copper strips, wove them into a 'fabric', carefully folded it and placed it into a kiln (1500? 1600? degrees f), he let it soak in the heat for a while (can't remember how long), then took it out and placed it into a water bath.  I think part of the colouring process might have come from the rapid cooling?  The piece had the colours you were looking for, as I recall.  \nI like the sound of what you're doing...hope it all works out for you...
516687
Silver will have a marking somewhere.\n\nIf you see one, go here and find out the info about that marking: http://www.silvercollecting.com/\n\nSterling silver will have a marking that says .925 (Or something similar.)\n\nPlated silver will have a marking that says silver plated.\n\nHome made polish? Try hot sauce. No, I am serious. It works. If you don't believe me, take some hot sauce and dip an old penny in it.
1156496
take your sodium bichromate and place it with sulfuric acid, this reaction will form sodium sulfate and bichromate acid (H2Cr2O7). keep the bichromate acid and mix liquid ammonia (NH3OH) with it. this reaction will form ammonium bichromate and water.\n\nBefore doing these reactions look up the propreties and safety for these chemicals\nhttp://ptcl.chem.ox.ac.uk/~hmc/hsci/chemicals/hsci_chemicals_list.html
961700
...\n_The_ First experiment was to observe the reaction when AgNO3 was added to the copper metal. The copper metal was placed in a test tube, (<--no comma needed here) and 0.1 M AgNO3 was added. Just after AgNO3 was added, the (<-- delete the) shiny silver things were observed. Finally, the copper metal was completely changed to shiny silver powder. In the chemical equation, (change to "only the color of")  (the color of only) Ag was shiny silver. Therefore the color of the product matched the color of Ag, and must have been powdered silver. In this experiment, because copper replaced silver in the compound, this was a single replacement reaction.
284044
Try changing the pH of the system and lowering the voltage.  If those don't help go the other way.\n\nhttp://www.cehs.siu.edu/Chemical/silver_waste.htm\n\nhttp://www.p2pays.org/ref/01/00048.htm\n\nhttp://www.finishing.com/73/82.shtml
785659
You mean like:\n\n"Azurite: Turns black with warm alkalis, hydrogen sulfide or sulfur fumes. "
646111
You can turn it black with an iodine solution, then turn it back with sodium thiosulphate solution. Neat trick.
976128
I believe the answer is conductive.  This is the process in which things are silver plated.  \n\nHere's how it goes.You fill a tray that has been lined with aluminum foil with salt water ( or is it plain water ? ).  You run a current through the aluminum foil.  The electrons in the the foil get excited due to the electrical current and start releasing aluminum ions ( Al-, I think )  Now, take your rusty, dull ' silver ' spoon.  Place it in the bath for about 2 hours.  Be careful,  electricity, water and living things don't mix well.  After 2 hours, remove the electrical current source and remove the spoon.  The free ions in the water would have coated the spoon, making it shining again.\n\nActually, toothpaste to clean the spoon is easier.
955607
polish silver--seriously!
1159691
Use any good silver or jewlery polish, and the oxidation will be gone. Bleach is mostly chlorine, which causes oxidation on silver. Toothpaste and an old toothbrush will also clean oxidation from silver, without being too abrasive. Lesson? Bleach and silver DO NOT MIX!
719136
Most black powders are a mixture of charcoal, sulfur, and saltpeter (sodium nitrate).\n\nMixing proportions are somewhat variable.
122259
wow open question here...what is the end result and use. if it is say for automobiles it would be copper, nickle and chrome for cheep jewerlery sure gold last...many possible answers
876437
The chemicals are a reducing agent like p-aminophenol, p-H2N-C6H4-OH, to make the black and gray parts of the image; and sodium thiosulfate, Na2S2O3 to dissolve away unwanted unreacted silver halide from the parts destined to be gray to white.\n\nI give the explanation for black-and-white negative film and print paper. Color film, slides, and prints are similar, but there are extra chemicals and steps involved.\n\nLight hits some parts of the film but not others. The silver halide, like AgCl, AgBr, and/or AgI exposed become sensitized. That is, they are susceptible to reduction to black silver metal. Unexposed silver halide is not sensitized. After development with the reducing agent, the sodium thiosulfate dissolves silver halide that is still there. This compound was once called sodium hyposulfite, and photographers still refer to it as "hypo." It is also called a fixing agent, and it is necessary to "fix" the image on film or prints in this way.