Can Fine Silver Really be Work-hardened?

A question was asked online about how to work-harden fine silver. Someone had embedded fine silver wire into metal clay earrings and they wouldn't hold their shape. There was quite a bit of discussion on work-hardening fine silver.

I researched the answer and found this information.

What is a metal's hardness?

A metal’s range of hardness differs depending on its particular mixture due to its arranged patterns of crystals and concentrations of mass specific to that metal. Each metal type has a range of hardness from soft to hard only relative to that metal. In other words, each metal type has its own range of soft to full hard ratings. 

How is a metal's hardness measured? 
There are several tests developed for measuring hardness, Mohs, Vickers, and Brinell. Through research, I found that Vickers is most often used for measuring a metal's hardness because it has one of the widest scales among hardness tests, known as the Vickers Pyramid Number (HV). The Vickers test observes the metal's ability to resist plastic deformation from a standard source.

When comparing relative hardness, Vickers lists fine silver as having the most softness compared with sterling silver and argentium silver. It rates fine silver as the softest metal when it is fully hardened when comparing it to argentium silver and sterling silver. Even at full hardness fine silver is still softer than soft sterling silver.

For earrings, the metal must be work-hardened so that it holds its original shape and can spring back into its original shape when slightly bent. Work-hardened fine silver still isn't able to become work-hardened enough. This is why copper is added to fine silver, making sterling silver, so that it can be work-hardened until it is spring-hard.

So, use sterling silver in your metal clay earrings in order to gain the needed spring-hard hardness. Make sure you don't fire the sterling silver higher than 1300˚F (704.44ºC) or the metal becomes brittle.

There are a few ways to work-harden sterling silver.

• Hammering the sterling silver with a rawhide or plastic mallet against an anvil
• Twist sterling silver wire (posts) with pliers or compress them with pliers
• Heat harden sterling silver in a kiln

According to Jörg Fischer-Bühner from Santa Fe Symposium® Proceedings, 2003. These are the steps for heat hardening sterling silver. 

Step 1: Check the sterling for any solder joints that may already be present.

Step 2: Heat the sterling to 1292°F–1346°F (700°C–730°C) for 30–60 minutes; adjusting temperatures if solder is present (if low-temperature solder is present, heat the piece only to 1000°F–1200°F). Quench in water.

Step 3: Heat the sterling again, this time to 572°F (300°C), holding at that temperature for 30–60 minutes. After cooling, Vickers hardness will range between 120–140dph; if lower temperatures are used, the sterling will not achieve this level.

Testing Your Kiln's Temperature

by Janet Alexander

 Now that most kilns have a computerized controller it’s become easier to control the kiln’s temperature. But, is the controller’s readout accurate? With so many varieties of bronze, copper, and silver metal clays, it has become important to know if your kiln’s temperature reading is correct. Otherwise, you may have problems with the clay not sintering correctly or getting too hot and melting. Additionally, the kiln should be tested for hot spots and cooler spots. Every kiln is different.





Testing can be done by using a pyrometer (which is how I used to adjust my kiln’s temperature before there were controllers) or by using kiln pyrometric cones. The pyrometric cones are supposed to bend when heated to a specific temperature for a certain amount of time. That means that pyrometric cones give a temperature equivalent; they are not simple temperature-measuring devices. According to a pyrometric cone manufacturer, cones have over 20 variables that can affect the cone’s bending, including the cone's composition, particle size of raw materials, type of forming process, moisture during forming, density of the cone, geometry of the cone, setting height, and angle and the heating rate. Atmosphere also affects bending behavior. Wow, that’s a lot of variables!  So, let’s look at testing with a pyrometer or a kiln test kit.

I used the kiln test kit sold by the PMC Connection. According to experts, the average kiln controller is accurate to ±10°F (±5.5°C) so keep this in mind while testing. Additionally, run the test several times but move the thermocouple to different areas of your kiln. Place it towards the back, near the front, off to each side, and etc. Test at different temperatures. I conducted tests at 1110˚F, 1200˚F, 1290˚F, 1470˚F, 1560˚F, and 1650˚F. I found that both readouts were within a few degrees of each other until the temperature got up to 1650˚F. Then they were off by 10˚F! So, I added another thermocouple from my casting kiln.  All three read different degrees but were within the accuracy range.

Now I know why my PMC3 clay had a crystalline look to it when I fired it at 1650˚F; it was getting too hot! So, now I lower the temperature of my kiln by a few degrees when setting it at 1650˚F.

The Test Kit Includes:

• Sensor  reader (tester)
• 9V Battery 
• K-type thermocouple TP-02A  
• K-type thermocouple TP-03 
• Case 

Use the TP-02A thermocouple (larger one) for testing your kiln. It has a temperature measuring range of (-58˚F to 1650˚F).



The Steps

1.  Install the 9 V battery into the unit’s back.

2.  Insert the plug into the bottom of the sensor reader making sure the plug’s polarity matches with the sensor’s polarity. 

3.  Insert the thermocouple into the kiln.

Caution: Don’t insert it past larger ceramic end or the wires will burn!

4.  Place the thermocouple near the kiln’s thermocouple for the first run of testing.

5.  Turn on the kiln and set it to hold at the test temperature for at least 15 minutes.

The sensor reader can read in Fahrenheit (F) or Centigrade (C). Turn it on by sliding the button from the center (off position) to the F (if measuring in Fahrenheit).

6.  The sensor displays its reading. Allow it a minute to stabilize to the temperature. Test at various temperatures. I found that my kiln was accurate until it reached over 1350 (F).

7.  When finished testing, turn off kiln and sensor reader and allow the thermocouple to cool before touching it.

Vibratory Tumblers

How is the Tumble-Vibe different from a rotary tumbler?

The basic difference between a vibratory and a rotary tumbler is the way the unit is driven.  A rotary tumbler consists of a barrel that sits on rollers causing the barrel to spin. Polishing media and the objects to be polished (jewelry pieces) are placed inside the barrel. As the barrel spins, the contents fall and slide over each other causing abrasion or polishing to the jewelry pieces located in the top 1-inch of the sliding media.  Jewelry pieces not located in the top inch are not polished. Some items can become dented due to the polishing media falling on the jewelry pieces.  It can take hours, days or weeks to bring a piece of jewelry up to a high shine using this type of unit. The lid on the barrel can leak or come off during the process.
 
A vibrating tumbler includes a bowl that sits on an out-of- balanced motor. As the motor moves, it causes the bowl to vibrate in all directions. The polishing media and jewelry pieces are placed inside the bowl. The bowl’s vibration causes the objects in the bowl to rotate around the bowl in two directions rubbing and polishing the jewelry 100% of the time. The items are polished much faster than a rotary tumbler and there is no chance of leaks, spillage, or denting of pieces. The items can be easily retrieved by opening the lid and fishing through the polishing media.

 A variety of different media, from cutting, to polishing, can be used in the vibratory tumbler including ceramic and plastic abrasives, walnut shells, and steel shot, making the vibrating tumbler more versatile than a rotary tumbler. The ceramic and plastic abrasives are sold in different grits. Polish is embedded in the walnut shell with the same polish jewelers use on buffing wheels. Steel shot, due to its hardness, is used as a burnisher. As it moves across the jewelry it rubs and burnishes the outer layer of the metal. 


General Instructions for the Raytech TV-5 Model

• The working capacity* of the Tumble-Vibe 5 is approximately .05 cu. ft. (three pints) or 4 pounds. The capacity includes the media, water and the work pieces.
• If the tumbler will be used for polishing as well as for cutting, always reserve one bowl strictly for the polishing media so it can remain free from embedded cutting grit.
• Successful finishing of most jewelry requires preparing the jewelry. Parts must be filed, sanded, or ground smooth over rough areas. Attempting to finish jewelry parts without adequate preparatory finishing can result in very long finishing cycles and loss of detail in the jewelry pieces.
• All plastic media or ceramic media should be broken-in before using. Media that is not broken-in may cause scratches. (See separate section, below, for breaking-in plastic media.)
• Keep a 70% media to 30% jewelry ratio. Too many items tumbling at one time can produce a poor finish.
• Always use cutting/burnishing soap with the media as required.
• If using steel shot, fill the bowl with water so that it just covers the top of the shot. Never completely fill the bowl with water. Too much water or soap hampers the media’s action. After tumbling, remove and dry shot.
• If using plastic or ceramic media, add 1 ½ oz. of water and a ½ teaspoon of polishing compound. Note: if the machine does not roll the media well at the start of a cycle, there is too much water or soap.
• Change water if it becomes gray or loses its suds. Rinse the bowl and clean the media.
• If the media tumbles too long without replacing the water, the jewelry pieces will absorb the gray sludge which is very hard to remove. The manufacturer recommends changing the water every three hours.
• When using ceramic media, don’t allow the bowl to run dry. This will cause premature wear on the bowl.
• Walnut or other shell media do not require water. Fill the bowl ¼” below the center cone and jewelry items.
• On average, dry polishing media is good for polishing up to 200 hours of use. When not in use, store in an air-tight container. See manufacturer’s instructions.
• Do not use media filled with silicon carbide or alumina powders as this will impinge and impregnated the metal surface and retard polishing.

NOTE: THE TV-5 UNIT CAN BE USED WITH UP TO 4 LBS. OF STEEL SHOT/CERAMIC MEDIA AND JEWELRY.

Breaking-in Plastic/Ceramic Media
1.   Place media into tumbler bowl.
2.   Add water and polishing compound /soap.
3.   Tumble without jewelry for one to two hours.
4.   Rinse media and bowl. Rinsing the media in a colander works well.

No More Maring Your Metal While Holding it in a Vise

All jewelry tools are made smooth without teeth so that they don't mar the finish of your work. But, sometimes it's helpful to have a vise with gripping teeth to hold various objects.




If you buy a bench vise at a discount store, it's not necessarily made for working with non-precious metals while making jewelry. You may need to smooth it in order to hold a piece of soft silver without marring it. So what do you do?









To solve this problem and have the best of both worlds by covering the jaws of your vise grip with copper sleeves.

1. Anneal the copper to make it malleable.
2. Cut two pieces of copper with the following dimensions: Width (equal to the width of the jaw) x Length (twice the height of the jaw).
3. Place one copper piece into the vise closing it tightly.
4. Using a rawhide mallet, hammer the copper down over the top of the vise.
5. Repeat the process with the other copper piece. 

Viola! You have a nice smooth surface inside the vise. When you need to use the vise with teeth, remove the copper.

11 Tips for Creating Bezel Settings for Cabochon Stones

Cabochon stones have a flat bottom with the sides rising up into a dome on the stone’s top. They are cut into a convex shape. There is a 90˚ angle where the bottom and the sides meet. The first 1-2 mm up the sides are at 90˚to the bottom and then the stone starts to curve over forming the dome.

The bezel setting holds the stone in place by coming just above the flat sides and folding over them right where the stone starts to curve into the dome.

The bezel is made of thin fine sliver wire.  Bezel wire comes in several heights and styles from plain to decorative.

When working with metal clay, the bezel wire can be embedded into the clay before sintering or it can be soldered on top of the metal clay after sintering.

Tips for Embedding Bezel Wire Into Unfired Metal Clay

• Make the clay base the bezel is being pressed into at least five cards thick. If using PMC Sterling silver metal clay, make the base six cards thick, allowing for the extra shrinkage rate.
• Choose the right bezel height. Allow extra height for 1mm of the bezel to be pressed into the metal clay. If the bezel is too tall, thin cardboard can be placed in the setting to raise the stone to the proper height. If cardboard can't be used (due to an opening in the base) then the bezel wire can be filed down to the proper height.
•  Fit the bezel so that the stone fits loosely inside of it. This allows for slight deformation while sintering.
• Cutting a hole in the base metal clay inside the center of the bezel helps keep the clay from warping while sintering. Allow for at least 4mm distance from opening to the bezel wire.
• Filling the bezel with casting investment (the same material as ring plugs) helps keep the bezel from deforming during firing. If you have an opening in the bottom of the bezel, cover it with kiln paper and then pour the investment into the bezel filling it just below the bezel's top edge.
• Adding decorative syringe or clay work around the outside of the bezel wire helps hold it to the base. 
• Coating the bottom edge of the bezel wire with oil paste makes the join more secure.

Tips for Soldering a Bezel on Fired Metal Clay

• The fired metal clay must be burnished in the area where the soldering takes place in order to close the pours of the porous metal clay.
• Use sterling silver solder either, hard, medium, or soft.
• If there is texture in that area, it must be smoothed in order to obtain a flush soldering join. It's best to smooth the area while the metal clay is in its dry stage. 
• The metal clay's shrinkage must be accounted for so that the bezel fits the sintered metal clay. Create a drawing of your design in the finished size, including the location and size of the bezel. Scan the drawing and then print it larger according to the shrinkage percentage of the clay you are using. Use the enlarged drawing as your template for making your metal clay piece. It also allows you to know where not to have texture! Here are the percentages of enlargement for some of the different metal clays.
  
  • PMC3 and PMC+ shrinkage after firing at 1650F for 2 hours is 15%.  Enlarge the drawing on the printer/scanner by 118%.
  • Art Clay Silver - low fire shrinkage is approximately 9%. Enlarge the drawing on the printer/scanner by 110%.
  • PMC Sterling shrinkage is 15 - 20%.  It's best to err on the large side, so plan on the 20% shrinkage rate. Enlarge the drawing on the printer/scanner by 125%.  

A Short Video on Casting in Cuttlebone

Here is my latest video on  how to cast a silver pendant in cuttlebone. If you have ever watched the first Hobit Movie they quickly show the ring being cast. The method they are using is cuttlebone casting.

This video shows how to prepare, carve a design, and cast sterling silver scrape into cuttlebone. It Shows the setup, how to set a half drilled pearl, and finishing techniques.

If you have scrap metal or metal clay fired pieces you don't like they can be melted into something new! 

Enjoy!

More Tips on Photographing Jewelry

In my last blog I discussed the basic setup of light, camera, white balance, and camera stand. What’s next? Sometimes the area around the table where you are taking photos can be a drain on the lighting or cause shadows. Here is what can be done to give a more even light on your jewelry. Use three number-4 USPS boxes taped shut and placed in a "U" shape on top of the cutting board. Then put a white piece of mat board against the back box.

By putting these boxes around three sides, and with them being white, they reflect the light back to the center area. If you want, cover the blue label with white paper. The white mat board acts as a backdrop when taking photos of earrings or anything vertical.


Photo Problem 1
The first problem piece of jewelry is a pendant with a hidden bail. It won’t lay flat and tends to fall to the left or the right.

My fix for this problem is a simple foam earplug. No, it’s not used! I cut it in half and, if needed, take that half and cut into two pieces. Wedge the two pieces under the pendant. Problem solved.

Problem 2
I want to take a photo of a ring standing up, but I don’t want to have it propped against anything. Glue dots are your friend! Use the extra strong dots found at Hobby Lobby.

There are two sizes, 2mm and larger. I use both depending on what I am trying to hold. In this case, I want to hold a simple ring on its end. I use a small dot. If its a heavy ring I use the large one.

Next time, I’ll discuss some other tips for photographing "trouble" jewelry.

Creating a Hollow Pendant

Lights, Camera, Action! Behind the Scenes - Shooting Quality Photos

  I was recently asked to submit 15 photos of artwork to a magazine for a local art tour of professional artists. We have over 25 artists. It shouldn’t be hard to find 15 quality photos, right?
Wrong! Some were out of focus, others showed junk in the background, or had their item laying in bright red cloth, and lastly the color was off. I find this happens more often than not.

So, in this blog series, I’m sharing some simple tips on creating quality photos of artwork (jewelry in this case).

Holding the Camera
The camera must have a camera stand. This removes most of the chances of blurry photos. They don’t cost that much, less than $36.  Most cameras have a screw hole in the bottom that allows for mounting on a stand. I read somewhere there is now a camera stand for iPhones too.

The Background
When setting up your shot, look in the background. Put jewelry on a neutral background. Bright colors, like red, blue, or yellow take away the focus of the main object. Additionally, colorful backgrounds reflect their color onto jewelry. Look at the reflection on the jewelry to see what color is showing, especially if it’s silver jewelry. A bright color makes the silver appear to be that color. For my background I use a white cutting board or a gray card.

Set the White Balance
Have you ever taken a photo that turns out blue or really yellow, but when you look at the setup it looks fine to your eye? That’s because the digital camera is picking up light different than your eye. All cameras have a setting that allows you to set the white balance. This setting is what changes that same shot to the corrected color. Different lights cause different colors. For example, fluorescent lighting adds a bluish cast to photos whereas tungsten (incandescent/bulbs) lights add a yellowish tinge to photos. Check your camera’s user manual to find the white balance setting menu. The easiest setting to use is "Auto". The camera makes a best guess of balancing on a shot by shot basis on the auto setting.

Lights and Lamps
I used to go outside on a cloudy day or find a shady spot to photograph my silver jewelry. Shade offers natural lighting, but the problem is the reflecting light. If I have a wall nearby the color reflects off my jewelry. A quick, easy, and cheap way to obtain natural lighting (I found out from Doug Baldwin) is to use CFL Daylight bulbs in a desk lamp. They can be bought at most hardware and discount stores. Use a desk lamp with the movable neck. This allows you to move it closer or further from your jewelry.

Softening the Light
A bare light bulb near shiny jewelry reflects a bright shine! The light must be diffused or scattered. An easy way to do this is to place tracing paper in front of the bulb (another tip from Doug Baldwin). If using the CFL bulbs they don’t get as hot as other bulbs, so it’s not as much as a fire hazard to do this. I lightly tape the tracing paper over the end of the lampshade. Of course, don’t leave the lights covered with paper for a very long time. It can cause a fire!

This is a good start on setting up your shots. Next time I’ll cover the secrets of making the jewelry behave and sit correctly!

Bench Tips: Filing Wire, and Cutting Wire Lengths

Many times as we work with metal hammering, texturing, or bending it, it becomes work-hardened. Some metal is sold in this hardened state. Too much work-hardening can make the metal crack! Texturing the metal can not only make it hardened but miss-shaped. It must be annealed or softened making it bendable.

Wire cut with flush cutters still have slightly pointed ends. Easily file them flat without bending the wire by placing the wire inside flat-nose pliers with just the tip hanging out the other side. This holds the wire while filing it flat.

Additionally, place the wire into the very point of the “V” shape in the bench pin with the end pointing upward. This holds the wire so it can be filed flat.







If you’d like to saw the wire instead of cutting it with pliers, make a channel across the top of the bench pin using a wood saw.

Now place the wire into the channel hanging it out the distance needed and saw it off against the side of the bench pin. Additionally, if cutting the same length wire (less than the width of the bench pin), mark the distance from the edge of the bench pin to the length of the wire on top of the bench pin. After cutting the wire, slide the next length out to the correct distance and then cut it.

Bench Tips Straightening Wire & Picking up Small Stones

I’d like to pass on some tips I use when working with metal or setting stones. Have you ever had a small piece of wire you wanted to use but it was all bent out of shape? Well here is a tip on how to make it straight again!
Bend it as straight as you can using flat-nose pliers. Place the wire on a smooth anvil or steel block with another anvil or smooth steel block over the wire. Slide the top block back and forth across the bottom one keeping the wire between the blocks. The wire rolls along straightening out as it rolls! Also, this is a great way to work-harden the wire!

Have you had a hard time picking up tiny stones while placing them into a setting? Roll some bee’s wax between your fingers into a point. Now use the point to pick up the small stone. To remove the stone from the wax, place it into the setting and roll the tip of the wax away from the stone. To clean the wax off the stone wipe it with a towel after setting it. If you plan to fire the stone in place, the wax burns off cleanly in the kiln.

Found on the model isle

Additionally, there is a product I found at Hobby Lobby called Pic- n- Stic. It works the same way for holding stones.

Holds without leaving residue

Fixing a Common Problem with Butane Torches

Problem Torches

Have you ever had a problem with the small butane torch acting like its empty even though you just filled it? That's because over time compressed air from the butane can fills the fuel container. The torch is full of air.

Easily remove this excess air by unscrewing the valve on the bottom of the torch allowing the compressed air to escape. Then re-tighten the screw and re-fill the torch with butane.

Tell me about some problems you are having and I will post the answers in a blog!

Janet Alexander

Tips From the Bench - Ring Gauges and Mandrels

Ring gauges and ring mandrels are used in concert to make rings. Ring gauges are used to measure the size of a person's finger and ring mandrels are used for manufacturing rings to the required size. In metal clay, we wrap the clay around a paper covered mandrel at the required size. In metal smithing, we wrap the metal around the mandrel at the correct size.

The typical  ring mandrel is a tapered and made of steel with the sizes engraved on it. In metal clay we also have the stepped mandrels sized in two sizes, either whole sizes or half sizes. 










Did you know that not all ring gauges and ring mandrels match? When you first purchase your ring gauges and a ring mandrel, check to see if they match and you might be surprised! Check several sizes, because some might be correct while others are not.

Size 7 is on 6 3/4" line

8 Fits correctly

This size 7 narrow ring gauge should slide down to the size 7 on the tapered ring mandrel, so the tapered mandrel is incorrect for this size.

The photo to the right shows that the size 8 wide band fits correctly on this size 8 short step mandrel.

Size 9 doesn't fit

But the size 9 wide ring gauge doesn't even fit onto the size 9 mandrel and neither does the narrow size 9 ring gauge.

(Interestingly the size 8 is on the same mandrel as the size 9!)







What's important to know is what to do if they don't match.

Since I measured the finger with the ring gauge, its important that I make the ring the size of the ring gauge. With the tapered mandrel, I slip the ring gauge onto the mandrel and draw lines on both sides of the ring gauge using a permanent marker. Now I work the ring around the mandrel between those lines.

With the miss-matched short stepped mandrel I wrap wax paper around either the size 8 or 8 1/2 mandrels until the size 9 ring gauge fits correctly.

I hope this helps those of you who have had problems with rings not fitting the finger.