Technical Article: “Mary Lee Hu’s Cookie Project, Made by Wei Zeng”

June 26, 2016

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SNAG’s new Collaborative Technical Articles Program focuses on archiving the wealth of information within our jewelry and metalsmithing community and making it available to future generations of makers. This inaugural collaborative article features a forming and soldering project made by Wei Zeng, following Mary Lee Hu’s “Cookie Project,” which Hu used to teach many beginning students during her long academic career. Forming, planishing, stick soldering, and a number of other critical skills and tips are all captured in this project and illustrated by Hu’s text and drawings and Zeng’s numerous process photos. A selection of Hu’s past students’ interpretations show just how versatile the “Cookie Project” can be. Learn and enjoy! –Victoria Lansford, Director of Technical Education

“Mary Lee Hu’s Cookie Project, Made by Wei Zeng”

Zeng Tech Article 1Zeng Tech Article 2Top image left and right: Wei Zeng. Other images by past students of Mary Lee Hu. Middle: Fujimi Terada (left) David Jaeger (right). Bottom: Gail Habda (left) Margaret Buchen (right).

Purpose: To quickly begin to familiarize students with sawing, annealing, sinking, planishing, soldering, and finishing 18 gauge copper or bronze sheet. It will give students a taste of hollowware in a beginning jewelry/metalsmithing class. This project is designed for students who have had little or no soldering experience. Some prior sawing experience is helpful.

Assignment: Cut two disks the same size and sink one deeper than the other. Fit them together and solder them. Design it so that one or both disks have been cut into or added onto. The finished piece can be a container, a piece of jewelry or a sculptural form.

Materials: Two, 4” squares of 18 gauge copper or bronze sheet, silver solder, other metal as needed.
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Tools and equipment needed: mallet, center punch, jeweler’s saw frame and blades, ball peen hammer, sand bag, variety of sized domed mushroom stakes, planishing hammer, files, abrasive paper, torch and pumice pebble pan on a turntable, flux and pickle, baking soda neutralizing rinse, polishing equipment. Cut one disk from each of two 4” by 4” pieces of 18 gauge copper or bronze sheet. (Could be anywhere from 3” to 6” disks).

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First put a straight edge on the opposite corners of the sheet and draw a short pencil line along it in the center of the sheet. Do this in both directions to make an X. This will mark the center of the sheet. Take a center punch and lightly hit it with a mallet to make a center punch mark in the center of the X. Do this with both sheets. Put one end of a compass into the center punch mark and draw a circle on each sheet as large as possible.

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Saw out the two disks with the jewelers saw. File the edges smooth and anneal both pieces, pickle, rinse, and dry the disks. They should be approximately the same size.

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Sink the disks. Place one disk, center punch mark side down, onto a sand bag and hit it with a ball peen hammer starting around the edge and working your way around to the center until it has a dished form. Do the same with the second disk.

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Choose a mushroom stake with a similar curvature as the dome of your disk and put it into a vise or stake holder. With a mallet hit, or bouge, your disk starting from the outside and working your way to the center until you have taken the hammer bumps out of your disk and it is fairly smooth. Do the same with the second disk until they have similar curved forms. Anneal them, pickle, rinse, and dry.

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Now take one of the disks and sink it again into the sandbag so that it has a deeper dish form. Choose a mushroom stake that has a similar curvature, but more curved that the first one you used, and bouge your disk so that it is fairly smooth.

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You should be able to place this second dished piece onto the first one, convex sides to the outside, and see that the more highly domed piece now has a smaller outside diameter, so that the first disk has small ledge sticking out from the edge of the second one. Anneal the second disk again. If you wish, you may repeat the sinking process on the second disk again to get an even deeper dish, but you will then need a more curved mushroom stake.

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Planish the disks. Using the mushroom stake that fits the disk, and starting in the center around the center punch mark, lightly hammer your whole surface with the more domed side of the planishing hammer, leaving overlapping hammer marks, and spiraling around from the center to the edge. You do not need to hit hard. Hit only a bit harder than simply letting the hammer drop onto your piece. You will find it easier to aim your blows, getting a very tight, overlapping series of marks if you move your disk slightly after each blow and keep your hammer going up and down in the same place.

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Your disk must fit onto the stake without air space underneath. As you hammer you should hear a solid noise, not a hollow rattle. This is very important; if there is space between your disk and the stake, you will be denting your disk, not just refining the surface to keep the same curvature.

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When you have finished planishing the whole surface, compare the disk to your other piece. You should notice that it has grown larger.

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Planish the second disk on the stake that fits its curvature. They should again be the same relative size to one another, but both now a bit larger. Planishing the metal has thinned it slightly making it larger. Be sure to hammer each area the same, not skipping areas and also not going over one area several times. If you do go over one area several times, the hammering will thin and enlarge the sheet, creating a raised area where it has been hit repeatedly. If when planishing, you notice that you have created an uneven curvature to your dome, that you have areas that are flatter, draw a line around the flat area, or “dent”, with a pencil and very lightly planish around the flat area on that line. The stake under the piece should push up the flat area to make it even with the rest of the piece’s curvature.

Take care that both your stake and hammer surfaces are smooth and polished if you want the surface of your piece to have smooth hammer marks. A little depression in your hammer surface will leave a corresponding lump on your piece – in every single hammer mark all over the piece… Then again, you might like this kind of texture.

If you want a completely smooth and polished surface, planish again with the flat side of the planishing hammer without annealing in between. Be sure to keep the hammer face flat on the piece. If you hit the piece with the hammer not square to the surface, but at too great an angle, the curved edge of the hammer face will make a curved dent in the surface of your piece. You can get this out by planishing more, but then that area will be a bit raised from the rest of the curve of the form because you have stretched it. When you are finished planishing, file, sand and polish the surfaces.

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File the edges smooth. After planishing, they will have become uneven. Check to see that the domes are still round and even. File the edge of the more domed piece at the angle needed so that it will fit flat against the surface of the other piece.

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Depending on your design, you will need to saw into one or both of your dished pieces before soldering them. While you could solder them together first and try to saw them in half – or “take a bite” out of your cookie – afterward, you will find it will not be easy to saw through the two surfaces that are now not close together. You will have much better control sawing each first before soldering them together. If your design does not have you cutting into either domed piece, you will need to drill one or more holes into one piece to let out the expanding and contracting air inside when you heat it to solder and cool it afterwards.

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To fit the two pieces together for soldering, first place them together, domed sides out, and if your design allows for this, rotate one of the pieces until you find the place where they seem to fit best and mark both pieces with a pencil mark so that you are always fitting them together at the same place. Now mark the more domed piece parallel to the edge everywhere it touches the less domed piece. File the edge at these places. This should lower those areas that touch, making the areas that do not touch closer and closer to touching. Keep doing this until your two pieces fit all the way around. Your solder will not fill a space larger than your metal is thick, so your pieces have to fit pretty well.

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Next you will use 18 or 20 gauge steel binding wire to bind the two pieces together so you can solder them. File four shallow notches opposite each other in the edge of the flatter domed piece – the edge that sticks out. Wrap binding wire around the two pieces, catching it in two of the notches, to prevent it from slipping off. Bind with another piece of binding wire at right angles to the first one in the other two notches. If you twist a loop in the binding wire before you wrap it around the pieces, you can use this loop and a pair of pliers to tighten the binding wire as needed.

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Sit your piece on the top of a mound of pumice pebbles in the center of your annealing pan, flatter domed side down. Flux around the seam and cut short lengths (about 1/4 inch) of 20 gauge wire solder and place into the seam about every inch or so, depending on how well your seam fits. Gravity will keep it at the seam. When heating the piece, split your flame so that half of it goes beneath the form heating the bottom piece and the other half is heating the top piece. Rotate the turn table with the pumice pan and your piece, keeping your flame split and heating both pieces until you see the solder start to melt. Remember that the molten solder will follow the heat of the torch so you can “pull” the solder around the seam. Always wear safety goggles when soldering.

This is a good form on which to try “stick soldering” if you wish. Put a small piece of solder onto the fluxed seam and hold about a foot length of the wire solder in your hand. Heat the piece, and when you see the small piece of solder melt, move the torch to one side of the piece while you gently touch the end of the solder you are holding to the seam along side of where the torch is hitting the piece. Make sure that the torch flame does not hit the wire of solder you are holding. It should be melted only by the heat of the metal it touches. If the metal is hot enough to melt the solder, you can just gently push it as it touches the seam and the solder will flow and zip along the seam towards the direction of the flame. Turn the turntable a bit, making sure the piece is hot enough, and add more solder just beyond where it flowed. Let the new solder again flow along the seam towards the heat of the torch. Repeat until you have gone all the way around the form.

When your piece is soldered, quench it in water and take off the binding wire. If you only have a small opening in your piece, you might be surprised at how quickly the piece filled up with water. That is because the hot air inside the piece cooled and contracted, sucking in the water. Pickle the piece, and neutralize it in a saturated solution of baking soda and water then rinse. If you only have a few drill holes and you think you might still have some pickle inside your piece, gently heat your piece until you no longer see steam coming out of the hole and quench in the baking soda water. Repeat the gentle heating, and quench in clear water. You do not want to leave pickle in a piece because it will come out in time and form a green crusty deposit around the hole.

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To clean up the solder on your piece file off the little ledge sticking out around the edge. Be sure to file and sand down parallel to the top more highly domed piece and not straight in from the end as you do not want to file right through the seam.

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Left: made by Lori Talcott while studying with Mary Lee Hu at the University of Washington in 1987. Other images also by past students of Mary Lee Hu. Top right: Julie Griffin, bottom right: Gayle Brown.

PDF of Article

Cookie Project concept, text, and drawings contributed by Mary Lee Hu

Project and process photographs by Wei Zeng

Past student photographs by Mary Lee Hu

Mary-Lee-HuAbout the Project Contributor:
Mary Lee Hu taught metals at the University of Washington for 26 years until her retirement in 2006, where her academic interests included the history of body adornment.  She served as SNAG President from 1977 to 1980. Her many honors and awards include multiple grants from the National Endowment for the Arts, being elected as a “Master of the Medium (metals)”, by the James C. Renwick Alliance of the Renwick Gallery, of the Smithsonian Institute, being named a Fellow of the American Crafts Council College of Fellows, and receiving the 2008 Twining Humber Award for Lifetime Artistic Achievement, Artist Trust, Seattle, Washington. Mary-Lee-Hu-artworkHer work appears in public and private collections around the world including the Victoria and Albert Museum in London, the Renwick Gallery at the National Museum of American Art in Washington, D.C., the Metropolitan Museum of Art in New York, and the Boston Museum of Fine Art.

Mary now splits her time between Seattle and Norfork, Arkansas where she tries to plant and keep up with gardens in both places between taking numerous road trips with her partner, Jim Wallace.  Luckily her metal work requires minimal tooling, so it can be done at either location.

About the Project Maker:
Wei-ZengWei Zeng was born in Guangzhou, China. She received her BFA with an emphasis in Jewelry and Metalsmithing from the University of Akron’s Myers School of Art in 2015. She creates organic, irregular forms with repeating patterns. She is inspired by the way cell structures look when viewed under the microscope, and creates jewelry from mixed media and sterling silver based on these elements.

Zeng is the recipient of several awards, including 2014 and 2015 scholarship awards from The University of Akron, and a GAR student award. Wei-Zeng-artworkShe has exhibited her work in a variety of exhibitions, most notably the Exhibition in Motion at the 2014 Annual Society of North American Goldsmith conference in Minneapolis, Minnesota, the Emerging Artists booth at the Boston Mills Art Festival in Peninsula, Ohio,  2016 Waterloo Arts Fest Juried Exhibition in Cleveland, Ohio and FUSION- The Merging of Art and Science Exhibit in Akron,Ohio.

About the Collaborative Technical Project:
SNAG’s new Collaborative Technical Articles Program focuses on archiving the wealth of information within our jewelry and metalsmithing community and making it available to future generations of makers. The articles are a collaboration between established educators of all types and emerging and established makers in the field. The educators contribute projects and lesson plans from past curriculum that focus on particular techniques or design challenges. The contributed projects are matched with a maker, who follows the project and documents the processes and his/her experiences in an engaging digital format.

Interested in participating? This Program is open to all types of educators, including high school teachers, professors, and continuing education and workshop teachers. Please email Victoria Lansford, Director of Technical Education, and indicate whether you would like to contribute a project or lesson plan or would like to create an article based on one. Contributors and makers are paid an honorarium for articles published by SNAG.

SNAG would like to take this opportunity to recognize our Corporate Members for their support: Aaron Faber Gallery, Halstead, NextFab, and Pocosin Arts.

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