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Trumpet Discussion Discuss Cleaning Silverplated Horns in the General forums; This is a topic that came up on the TH a while ago. I figured that this would be a ...
  1. #1
    Piano User Bruce Lee's Avatar
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    Cleaning Silverplated Horns

    This is a topic that came up on the TH a while ago. I figured that this would be a good place to post this.

    I recently had an inquiry, from a customer of mine, about cleaning his goldplated trumpet which is showing "tarnish". Basically, it's the silverplated base that's tarnishing.

    Here's a science class project that will benefit us:

    Tarnish Removal from Silver
    Elizabeth A

    Purpose:This demo provides students with a practical chemical reaction, and demonstrates principles of electrochemistry.

    Materials:

    a tarnished piece of silver
    a pan or dish large enough to completely immerse the silver in
    aluminum foil to cover the bottom of the pan (*Note, these two materials can be combined by using a disposable aluminum pan)
    enough water to fill the pan
    a kettle to heat the water (and oven mitts if you plan to move the pan)
    baking soda, ~ 1 cup (depends on the amount of tarnished silver you have)
    Procedure:

    Line the bottom of the pan with aluminum foil (or use your aluminum pan).

    Set the silver object on top of the aluminum foil, making sure the silver touches the aluminum.

    Heat the water to boiling, and pour it in the pan (*be careful not to burn yourself), completely covering the silver.

    Add baking soda (as needed); a good rule of thumb is ¼ cup per 1 liter.(Note, the mixture will froth a bit and may spill over; so you may want to put the pan in a sink – use oven mitts).


    The tarnish should begin to disappear quickly.You may need to let it sit, reheat the water, and/or add more baking soda if the silver is badly tarnished.


    Key Questions:

    *** These should be asked before starting the demo.***

    Why does silver tarnish?/How does it become tarnished? (see explanation)
    Who has polished silverware in the past?
    What commercial methods have you used?
    How do those cleaners work?/What do you do to make them work?
    Why/How might baking soda, water, and aluminum remove silver tarnish?
    Work out the first formula with them, and write it on the board/overhead.From the teacher’s introduction, students will know sulfur reacts with silver to form tarnish, therefore, they’ll be able to get the first part of the reaction; they also know you want to recover silver (ie. it’s a product).
    Have the students work out valences, and balancing.

    Now let’s see what happens.Have one or all students come up to observe.Show what the silverware looks like before it’s polished.

    Work out formula 2 with the students.Have them figure out what the baking soda reacts with, and ask them the two common products (water and carbon dioxide).You may have to tell them a gas is produced (“Which one?”).


    ***These could be asked before the baking soda has been placed in the water.***

    Why is the water hot?
    Why is baking soda added?
    What will happen to the water when baking soda is added?
    What will happen when the silverware is placed in the solution?
    ***These could be asked after the tarnished silver has been placed in the water.***
    What happened?/What did you observe?
    Why is the aluminum necessary?
    How does this design work to remove the silver tarnish?
    Explanation:

    Silver tarnishes because it undergoes a chemical reaction with sulfur-containing substances in the air.Silver combines with sulfur to form silver sulfide, which is black, and darkens the silver.The silver can be made shiny again by removing the silver sulfide coating from the surface.


    Two ways to remove the silver sulfide are to: remove it from the surface, or reverse the chemical reaction and turn silver sulfide back into silver. The first method involves polishes that remove some of the silver during polishing.The above demo uses a chemical reaction (which is sped up by heating the water) to convert the silver sulfide back into silver, without removing any silver.


    Aluminum has a lower ionization energy (energy required to remove electrons from an atom of the element) than silver.As a result, aluminum is oxidized (loses electrons and oxidation number increases), and silver is reduced (gains electrons and oxidation number is reduced).Depending on the amount of tarnish, the silver will be bright and the aluminum foil may be brown with tarnish (aluminum oxide), in a short while.The silver tarnish is "transferred" to the aluminum via reactions, which occur instantaneously, as follows:

    3 Ag2S(s) + 2 Al(s)+ 3 H2O(l) * 6 Ag(s) + Al2O3(s) + 3 H2S(aq)

    silver sulfide + aluminum + water * silver + aluminum oxide + hydrogen sulfide

    (* Note, this reaction can be done without the baking soda, but it takes longer to see results).


    The baking soda (sodium bicarbonate) reacts with the (sulfur-smelling) H2S:

    3 NaHCO3(aq) + 3 H2S(aq)*3 NaHS(aq)+3 H2O(l)+ 3 CO2(g)

    baking soda + hydrogen sulfide * sodium hydrosulfide + water + carbon dioxide

    The CO2 gas can be observed escaping from the most tarnished parts of the silver.


    The silver and aluminum must be in contact with each other because a small electric current flows between them during the reaction.This type of reaction, which involves an electric current (because atoms are charged), is called an electrochemical reaction, and is used in batteries to produce electricity.
    I'm not so comfortable with the boiling water part. Maybe it doesn't need to be THAT hot! Anyways, I hope that this is helpful!

    Best always,
    Bruce

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    for gold plate I think flip use to suggest tarni-shield (???) - a 3m product... I have had success with flitz myself.

    -marc

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    I thought that tarni-shield was for silver only (I use it on my silverplated horns about every 6 months): one of the "benefits" of gold plate being that it did NOT tarnish and could be simply wiped off. Or did I miss yet another "boat"?

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    As Bruce had mentioned at the top, the silver under the gold can actually tarnish from time to time. I had a small dark section on my horn and some flitz took it off...

    -marc

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    So the silver tarnishes "through" the gold with the oxides appearing on the outer surface of the gold plate? Does this in any way appear to damage the gold plate itself?

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    Piano User Bruce Lee's Avatar
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    Here's some more improved information:

    Cleaning Silver

    Silver, when properly maintained, will yield generations of enjoyment. The following cleaning instructions have been tried and proven in my silver restoration & conservation studio. These instructions are for those individuals who are maintaining the vast majority of antique and new silver (fine silver, coin, sterling, Britannia, and other alloys) in the world. Solid gold is generally cared for in the same way as silver. Objects that are silverplated or goldplated over precious metal or basemetal must also be cleaned with the same care as solid metals. Museum conservators generally clean silver and gold in their collections by using a calcium carbonate/denatured alcohol mixture which will not be discussed here, for most individuals would prefer not to spend hours cleaning a teapot! Also, the more technical aspects of silver care have been kept to a minimum and are more appropriate for a general audience.

    Silver is tarnished by sulfur-containing materials, particularly hydrogen sulfide (H2S). The most common tarnish-causing elements are wool, felt, food (eggs, onions, mayonnaise), fossil fuels, rubber bands, latex gloves, carpet padding, and certain paints. Tarnish is accelerated in a humid environment. Oily salts from our fingers may, if not removed, show up as corrosion patterns that may have to be professionally removed.

    If there is no tarnish present on your silver, use a phosphate-free detergent to clean it after use. Silver that is used, then gently washed and dried immediately, will require seldom tarnish removal. When hand- washing, do not allow your silver to come in contact with a metal sink—it will scratch.

    Tarnish is easily removed when first noticed (usually a yellowish tint), and will become increasingly difficult to deal with as it turns to light brown and eventually black. Frequent light cleanings, (washing the object with a phosphate-free detergent may be all you’ll need) are preferred to waiting until the tarnish gets so stubborn that more abrasive polishes would have to be employed.

    The polishes and cleaners listed here can be found in your local hardware store, department store, pharmacy, or listed distributors. 3M's Tarni-Shield™ Silver Polish and Twinkle® Silver Polish are by far the least abrasive of the commercial cleaners, and Tarni-Shield™ has a much more effective tarnish barrier than Twinkle. Goddard’s™ Long Shine Silver Polish and Silver Wash, and Wright's® Anti-Tarnish Silver Polish and Silver Cream (this product offers no tarnish protection) are all recommended in removing heavier tarnish and residue. Use Wright's® Silver Cream to remove stains on steel knife blades. If the choice is between a polish that protects better but is more abrasive, and one that does not protect as well but is far less abrasive, go with the less abrasive polish. Polishes that are meant to be washed off are less abrasive because they use a liquid to suspend the polishing ingredients.

    Don’t use polishes that have dried-up; the abrasive particles are now much too concentrated and will harm your silver. Never use steel wool (too abrasive and rust may result if not fully rinsed from the interior of an abject), Scotch-Brite™ and scouring pads (too abrasive), or dips (too toxic...see Chemical Dips).

    You may have noticed after cleaning your silver, that a purplish stain remained. This stain, or oxidized copper, is called firestain, and can be found on many colonial through nineteenth century pieces. It is not generally seen on pieces that have been produced by the large silver companies after the 1800s, though, many one-man silversmithing shops still use this technique. This depletion process leaves the object with a pure silver surface which is more resistant to tarnishing. The stain develops in sterling and coin silver when oxygen penetrates the outer surface of the object during brazing, oxidizing the copper content. Fine silver is left on the surface when acid chemically removes the oxidized copper, though, copper may be oxidized below the surface. These pieces will show this stain after many years of polishing.

    Do not mistake this stain for tarnish! Attempting to remove it will only damage your prized piece.

    Use this technique if you are polishing an object WITH porous attachments:


    Wooden handles & finials, ivory insulators, felt used on the bottoms of candlesticks and compotes can become damaged when introduced to excess moisture. Also, hollow areas that will not dry (beaded rims, handle sockets with minute holes, etc.) or if there is no source of water, use Goddard’s™ Long Shine Silver Polish. Of the polishes listed above, this is the only one that is meant to be allowed to dry and buffed off. Always use 3M's Tarni-Shield™ if you can avoid introducing moisture to porous attachments or hollow areas. Use a large cotton ball with a small amount of polish and rotate the cleaning surface regularly to expose unused surfaces, for elements in the tarnish can be very abrasive. Rub the object in a straight, back-an-forth manner so to maintain a uniform appearance. Avoid rubbing in a circular motion. Let the polish dry and remove it with a Selvyt™ cloth (preferred) or cotton dish towel. Selvyt™ is a lint-free, untreated, 100% cotton wiping cloth which is also excellent for highlighting ornament. Always use the smallest amount of polish necessary.

    A dry horsehair brush can be used to remove dried polish and grime from crevices and ornament on previously polished pieces before repolishing. A wet brush is preferred which will soften the bristles and aid in lifting the polish from the object's surface with minimal abrasion. When used wet, the bristles alone will not scratch the silver. A wet toothpick will get into the smallest areas.

    Use this technique if you are polishing an object WITHOUT porous attachments:


    If you are cleaning a piece with no porous attachments, rinse the object first to remove any pollution that may have settled on the object. These contaminants, which may be more abrasive than the polish you will be using, can actually scratch the silver if rubbed into the surface. Apply Tarni-Shield™, Twinkle®, Goddard’s™ Silver Wash, Wright's® Anti-Tarnish Silver Polish or Wright's® Silver Cream with a moist cellulose sponge. If you feel it necessary to protect your hands from moisture, use nitrile gloves which contain no ingredients to tarnish silver. Rub the object in a straight, back-an-forth manner so to maintain a uniform appearance. Avoid rubbing in a circular motion. Rinse the sponge regularly, for elements in the tarnish can be very abrasive. Flattened cotton swab heads with very little silver polish applied are excellent for cleaning between fork tines. The swab will last longer if you run it parallel within each opening.

    Dried polish can be removed by patting the area with a warm, wet cotton ball or a wet horsehair brush. Rinse the object with warm water then dry with a Selvyt™ cloth or cotton dish towel immediately to avoid spotting.

    Use a rouge cloth to restore the original luster to silver and gold which has been dulled by heavy tarnish. Unlike the Selvyt™ cloth which is untreated, the rouge cloth contains a polishing agent, normally rouge. I advise using untreated, heavyweight cotton inspection gloves to avoid finger prints when cleaning and storing your freshly cleaned objects. After dinner, if you prefer not to apply a tarnish protectant, wash all utensils by hand with a dishwashing detergent and warm water then dry immediately with a Selvyt™ cloth or cotton dish towel. Do not allow silver to come in contact with a metal sink, as the sink itself can scratch, especially if it’s been heavily abraded over time. And, do not allow food to remain on your flatware for extended periods; some foods contain ingredients that may cause stains, tarnish, or corrosion.

    Toothpaste as a Silver Polish


    Toothpaste should NEVER be used as a silver polish. Some toothpastes contain baking soda or other ingredients which are much too abrasive; even trace amounts may cause serious damage. Only use polishes that are specifically formulated to remove tarnish from silver.

    Chemical Dips


    Chemical dips work by dissolving the tarnish on an object at an accelerated rate. Dips are used by silver restorers when heavy, black tarnish cannot be removed with liquid or paste polishes. Chemical dips are wiped over the object with a cellulose sponge or cotton ball to avoid over cleaning, for submerging the entire piece for long periods will cause pitting of the object's surface and remove factory-applied patinas. This surface will act like a sponge and more readily absorb tarnish-producing gases and moisture. The object may then require professional polishing to restore the original finish.

    These dips are made up of an acid and a complexing agent. Acids are corrosive and will damage niello, bronze, stainless steel knife blades, and organic materials such as wood and ivory. The ingredients can be harmful to the user, which is why silver restorers work in a well ventilated area and wear nitrile gloves. Chemical dips should never be used on objects that have sealed components, such as candlesticks and trophies with hollow feet or teapots with hollow handles. Once the dip leaks into the cavity through small holes or imperfections in the joints, it becomes virtually impossible to wash the chemical out. For these reasons, this cleaning technique should only be used by a qualified restorer.

    Electrochemical (Galvanic) Reduction

    This process uses an aluminum or aluminum alloy plate and warm solution of sodium carbonate (washing soda). When the object comes in contact with the plate in the solution, it removes only light tarnish, not the thick, black tarnish produced by years of neglect.

    Pitting of the object can occur if the aluminum plate is not periodically cleaned. Another not-so-obvious problem is scratching of the object when in contact with the plate.

    Objects cleaned by this method may tarnish more quickly than silver that has been polished, for the object's surface will act like a sponge and more readily absorb tarnish-producing gases and moisture. The solution can also seep into hollow areas such as coffee pot handles, unsoldered spun beads around the tops of lightweight holloware, weighted pieces with minute holes, and any porous attachments. For these reasons, this cleaning technique is not recommended.

    That should just about cover it!

    Best always,
    Bruce

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    Now that's what I call a definitive treatise on the subject! Thanks, Bruce.

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