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Cool Tools Metal Clay Ring Sizers
Cool Tools Metal Clay Ring Sizers


Our Metal Clay Ring Sizer pellets are placed inside rings to constrain the metal clay to US ring sizes during firing. Be sure to download our complete instructions for use which includes our ring forming chart. These pellets are single use and dissolve in water after firing. Package of 3 pellets.

Learn how to make a ring out of metal clay below.

Click here to view or download instructions.

Item# Item Name Price: Qty
RDP-100 Cool Tools Metal Clay Ring Sizers - Size 10
RDP-105 Cool Tools Metal Clay Ring Sizers - Size 10-1/2
RDP-110 Cool Tools Metal Clay Ring Sizers - Size 11
RDP-115 Cool Tools Metal Clay Ring Sizers - Size 11-1/2
RDP-120 Cool Tools Metal Clay Ring Sizers - Size 12
RDP-125 Cool Tools Metal Clay Ring Sizers - Size 12-1/2
RDP-040 Cool Tools Metal Clay Ring Sizers - Size 4
RDP-045 Cool Tools Metal Clay Ring Sizers - Size 4-1/2
RDP-050 Cool Tools Metal Clay Ring Sizers - Size 5
RDP-055 Cool Tools Metal Clay Ring Sizers - Size 5-1/2
RDP-060 Cool Tools Metal Clay Ring Sizers - Size 6
RDP-065 Cool Tools Metal Clay Ring Sizers - Size 6-1/2
RDP-070 Cool Tools Metal Clay Ring Sizers - Size 7
RDP-075 Cool Tools Metal Clay Ring Sizers - Size 7-1/2
RDP-080 Cool Tools Metal Clay Ring Sizers - Size 8
RDP-085 Cool Tools Metal Clay Ring Sizers - Size 8-1/2
RDP-090 Cool Tools Metal Clay Ring Sizers - Size 9
RDP-095 Cool Tools Metal Clay Ring Sizers - Size 9-1/2
Check the items you wish to purchase, then click 'Add Qty to Cart'

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Making Metal Clay Rings

Making a ring from metal clay may seem a little intimidating at first, but it's actually very easy. We have listed the essential tools you'll need and give you ring building fundamentals to get you started.

Basic Ring Forming Tools

Finger Gauge – to measure a finger for ring size

Ring Mandrel – to form a ring

Ring Sizer Pellets – to control the size of a ring

Freezer Paper – to keep a formed ring from shrink-locking to the mandrel during drying

Invisible Tape – to make a tube from freezer paper

Finger Gauges

A finger gauge is used to determine ring size. There are several different types: ring-style finger gauges, paper gauges and strip gauges.

Ring-style gauge - a set of plastic or metal rings. There is one ring in each size that can be tried on until the proper size is found. Ring-style gauges are available in plastic and metal. The plastic gauges tend to have sizes on only whole and half sizes but are most economical. Metal gauges often have quarter and three-quarter sizes. The most expensive metal ring gauges come in wide and thin bands.

Paper gauge - a miniature tape measure for the finger.

Strip gauge - works like a cable tie. A plastic strip is cinched onto the finger and reveals the size at a plastic stop. The plastic strip will measure in whole, half, quarter and three-quarter sizes.

Ring Mandrels

A ring mandrel is used to form a ring on. Mandrels may be individual rods or a single mandrel that is either stepped or tapered. A ring can be formed to the most common sizes with any of the mandrel types. Here is a detailed description of the main types of mandrels that can be used for ring making:

Multi-Mandrel – The Multi Mandrel is our favorite ring-making tool because it’s so easy to use and so versatile. The lightweight Multi-Mandrel was designed for creating wax ring models, but it's absolutely perfect for making metal clay rings. The set of 6 ring size mandrels are 5" long. There are two sizes on each mandrel. The smallest mandrel has size 4 on one end and 5 on the other; the largest has sizes 14 and 15. The mandrel is fitted into a stud on the mandrel stand. The stand can be placed so the mandrel is horizontal or vertical. The mandrels can be rotated on the stud, giving you access to every possible angle. The mandrels are available in whole and half sizes, and in aluminum or wood. A wood storage rack to store the mandrels is also available. The double-ended mandrels offer lots of ring-making real estate with no tapers to throw off your sizing. Multiple projects can be created simultaneously. The only drawback to this system is that you cannot use the mandrels to round or size a ring. We recommend the aluminum version over wood because the wood can expand with humidity and can be damaged much more easily than aluminum.

Tapered Ring Mandrel - Tapered ring mandrels are made of steel so the metalworker can form metal with mallets and hammers. There are mandrels with sizes engraved into the steel, and there are mandrels with no markings at all. A finger gauge can be used to mark the right size on an unmarked mandrel. Any tapered mandrel will affect the accuracy of the ring size on wide rings. A wide ring formed on a tapered mandrel will have a difference of 1 to 1-1/2 ring sizes from one side of the band to the other which can result in a ring that is too tight or doesn't fit at all. To overcome this problem, be sure to center the middle of the ring at your desired size on the mandrel for a good fit. We also recommend that you make a wide ring one size larger to account for the width. A wide ring will always feel tighter than one with a narrow band of the same size. Some mandrels have a hole in the end to allow them to bit fitted on a stand, and there are also mandrel rests to hold the stand.

Another type of tapered mandrel is made of wood. A wooden tapered mandrel is made for polishing rings. We do not recommend using this type of mandrel because a ring polishing mandrel is much shorter than a steel mandrel, which means the taper is more extreme. This mandrel is very handy for polishing or stone setting, drying and drilling.

Tapered aluminum mandrels are called ring sticks. A ring stick is a gauge meant for finding the size of a ring. The ring is slipped onto the mandrel and the size is determined by the markings on the ring stick.

A stand is available for aluminum and steel tapered mandrels that raise them off the work surface by about 3", giving you plenty of room to work. If you don't want to invest in a stand, a simple set of feet can be made from polymer clay.

Low-Cost Mandrel Stand - Soften a 1 oz. block of any brand of polymer clay. Take Ό of the clay and form it into a ball. Form the remainder of the clay into a tall cylinder. These are the feet for the mandrel. The small ball holds up the large end of the mandrel and the cylinder holds up the small end. Position the ball and the cylinder so the mandrel ends can rest on them and press the mandrel into the clay to create a seat. Remove the mandrel. Bake and cool the feet.

Stepped Ring Mandrel - Stepped ring mandrels have about 1 inch of space for each ring size. Some stepped mandrels come already mounted on a rotating stand, making them very handy for metal clay ring making, but a bit heavier than the Multi-Mandrel system.

A simple sleeve made from freezer paper that fits over the mandrel allows easy removal of the ring as it dries and protects from galvanic corrosion. No matter what kind of mandrel is used, rings are never formed directly on the mandrel because metal clay shrinks a little bit as it dries, making it impossible to get the ring off the mandrel without damaging it. And if you did form a ring directly on a metal or aluminum mandrel, you'd soon learn about galvanic corrosion. Galvanic corrosion is something that happens when two dissimilar metals are in contact with each other in the presence of an electrolyte. The electrolyte creates an electrical charge that then corrodes both metals. The water and binder in metal clay create the electrolyte. With steel, galvanic corrosion will be rust in your clay that turns black when fired and cannot be removed. It will also leave pits in the steel mandrel. With aluminum, you'll get white and grey oxides and pitting in the clay that will turn black when fired and cannot be removed. The aluminum will be pitted and corroded. A simple sleeve made from freezer paper that fits over the mandrel allows easy removal of the ring as it dries and protects from galvanic corrosion.

Mandrel Sleeve - To make a sleeve, cut a strip of freezer paper about 1" wide and 3" long. Wrap the paper, shiny side out, around the mandrel. Trim the strip so one end just overlaps the other end and use a small piece of tape (about 1/4 inch long) to hold it in place. The tape should not be on the mandrel. Make sure the tape is on the paper only so the sleeve can be slid off later. Test to be sure you haven't taped the paper to the mandrel.

Ring Sizers

A Ring Sizer is a special pellet or plug that is placed inside the ring shank during firing to control the size. The pellet is made from a special material that does not shrink or burn during firing. As the metal clay sinters, it shrinks tightly around the pellet so the ring is the exact diameter of the pellet after firing. After cooling, the ring is put into water to dissolve the pellet. Rings cannot be formed directly on Ring Sizer Pellets because they would not have any room to shrink and would tear.

Metal Clay Ring Sizers – Cool Tools Ring Sizers are pre-cast pellets available in half and whole US ring sizes from 4 to 12. Match the ring sizer pellet size to the ring size you wear. Our Metal Clay Ring Sizers have the size molded into the end of the pellet so there is never a mix-up in sizes.

Ring Sizer Mold – The Cool Tools Ring Sizer Mold is a cost-effective way for metal clay artists to cast their own Metal Clay Ring Sizer Pellets as needed. The molds are available in whole, half and gang sizes. A half sized mold creates one pellet of each half size from 4 to 12. A whole size mold makes one pellet of each whole size from 4 to 12. A Gang mold make 9 pellets all the same size. You'll need investment or paper clay to cast the Ring Sizer Pellets.

Investment - is a product that is used in casting metals. Investment is mixed and poured into the Ring Sizer Mold to cast ring sizers. Any type of silver, gold or platinum casting investment can be used; however the mold works best with a crystobolite-based product. Crystobolite is a silica-bearing product, so it must be used with a dust mask, or use a silica-free investment.

Our Ultra-Smooth investment makes Ring Sizer Pellets that are very smooth and strong, do not shrink, and can be de-molded in 25 minutes after pouring. They can also be used immediately after de-molding even though they are still slightly damp.

Silica-Free Investment is an alternative that does not contain crystobolite. Ring Sizer Pellets made from Silica-Free Investment are not as dense as traditional investment, and require 2 hours to set up before they can be de-molded, and must be allowed to dry completely before use. When casting with silica-free investment, a soapy-water release must be sprayed into the mold to avoid sticking which is made simply by adding a few drops of soap to plain water in a spray bottle.

Steps to Making a Ring

1. Measure your finger to determine your ring size. Form your ring 2 sizes larger than this. For example, if your ring size is 7, you would form the ring at size 9 (we recommend adding an additional 1/2 size when the ring shank is wide and 5 cards or less in thickness).

2. Fit your mandrel with a mandrel sleeve (see instructions above). The ring is created directly on the sleeve. As the ring begins to dry, it will shrink a little. This can be enough to stress a seam and cause it to tear. To avoid tearing, allow the ring to dry for 10 or 15 minutes, and then slide the sleeve down one size on the mandrel so it can complete drying on the outside without any strain. Once firmed up, the sleeve with the ring on it can be slid off the mandrel and dried on a cup warmer or other drying device. Once the outside feels completely dry, the mandrel sleeve can be removed and the inside can finish drying. Do not try to remove the mandrel sleeve until the outside of the ring feels totally dry to avoid breaking or distorting the ring.

3. Once your creation is ready to fire and completely dry, place a Ring Sizer Pellet in your desired ring size inside the shank and fire. Don't worry that the ring is larger than the pellet. During sintering the ring will shrink tightly around the Ring Sizer Pellet, resulting in a ring that is exactly the size of the pellet. If the top of the ring is wider than the shank, the ring will have to be propped up so it doesn't warp. The ring can be placed on a fiber blanket or in a dish of vermiculite or alumina hydrate for support. Be certain that nothing gets between the Ring Sizer Pellet and the metal clay as it sinters and shrinks.

4. After firing and cooling, the Ring Sizer Pellet is removed from the ring by dissolved it in water. The ring is then polished and finished as desired.

Ring Making Tips

What Clay To Use

Sterling silver clays, such as EZ960, should be your first choice in choosing a clay in which to create a ring, as it is much harder and more durable than fine silver clays. Sintered fine silver is soft and brittle, so it dings up pretty quickly and it’s fairly easy to break when its thin. If you choose to use fine silver as a medium to create rings, low-fire clays such as ACS 650 Low Fire and PMC 3 have the smallest particle sizes so they sinter more densely than other formulas and are the preferred clays for creating fine silver rings.

Recommended Firing Schedule for Silver Clay Rings:

EZ960: 1675F for 2 hours in a digitally controlled kiln provides maximum strength. If you are firing flat, and then bending the metal post firing, we recommend 1675F for a full 4 hours to ensure complete sintering and absolute maximum strength. We do not recommend torch firing EZ960.

PMC 3: 1650F for 2 hours in a digitally controlled kiln for maximum strength

ArtClay Silver Low Fire:1650F for 2 hours in a digitally controlled kiln for maximum strength

Fine silver rings can be fired with a torch; however the end product will not be nearly as strong as kiln firing. Consider the fact that a flat strip made from PMC3 and fired at 1650F for 2 hours can be formed on a ring mandrel into a ring. The same strip fired by torch will break when attempting to form it on the mandrel because sintering is a process that happens over time and the longer the piece is left to sinter at ideal temperature, the more fully it is sintered and therefore the stronger the final product is.

If you torch fire rings, be very careful in wearing them. Treat them as cocktail rings. We also wouldn't recommend selling rings that have been torch fired because customers will expect a silver clay ring to be as strong as a sterling silver or gold ring, and they just aren't. If you plan to sell your rings to the public, fire them in a digitally controlled kiln for maximum strength, tumble polish to give added strength through work hardening. Be sure the customer understands that metal clay is a sintered material that does not have the same properties as sheet stock or cast items so they should treat their rings with care.

How Thick to Make the Shank

Our recommendation is 5 cards thick.This is a good standard for rings. For heavily textured rings, make sure you have a floor of at least 3 cards thick. Because sterling silver is harder and more durable, shanks can be made less thick than their fine silver counterparts.

Making a Half-Sized Ring with a Whole Sized Mandrel

If you need to make a half-sized ring and only have a whole sized mandrel, make the mandrel half sized by making the mandrel sleeve thicker. Simply cut a longer piece of freezer paper and wrap it one complete revolution around the mandrel. You'll need to use the proper half-size Ring Sizer Pellet when firing.

Removing the Ring Sleeve

Once the outside of the ring feels dry, remove the sleeve so the inside can dry. Place a needle tool on the top edge of the sleeve and collapse it downward. Pinch the sides of the sleeve together and slide it out of the ring shank. Be careful not to nick the inside of the shank as it will be soft. The ring can be speed dried on a dehydrator or a hot plate or left to air dry. Be very careful in handling the ring at this point since the inside is still wet and the ring can easily collapse. Save the sleeve! It can be used again and again.


When you have 2 ends that meet and you want to blend them, use a small ball stylus or clay-shaper to "stir" the ends together rather than trying to add water and paste them together. The result is a much more reliable joint.

Seams should be joined in a bias cut rather than a straight up and down cut. This gives more area to joint and results in a stronger seam.

Use the seam as a design element or position the seam so it is at the top of the ring and will be covered with a decoration or top.

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