Wednesday, October 3, 2012

Research on the Merode Cup to Prepare for Construction

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About the cup:

Benton, Janetta Rebold. Materials, Methods, and Masterpieces of Medieval Art. Praeger, 2009.

Page 166 "The earliest known example of plique-a-jour, and one of the finest examples of this technique, is the Merode Cup, made in the early fifteenth century in France. This covered cup is made of silver-gilt, decorated on both cup and cover with a band inset with panels of translucent plique-a-jour enamel made with gold cells. This unique cup, measuring only 6 7/8 high and 3 5/8 inches in diameter.." size of the actual piece.

"The Merode Cup." The Merode Cup (Cup and Cover). Victoria and Alber Museum, 1978. Web. 16 June 2012. <http://collections.vam.ac.uk/item/O93263/the-merode-cup-cup-and-cover-unknown/>.

Silver gilt and plique-a-jour enamel. The inside where the plique-a-jour panels are is plain and separated by bands left in the metal. The plique-a-jour is held in place on the outside with molded frames decorated with applied leaves. The outside of the cup is decorated with pounded scrolling designs. The base of the body is encircled by a girdle. The upper part of the foot is decorated with pounded rosettes and encircled by a girdle. Below the band is stamped with sunken circles pierced with holes (for the possible attachment of pearls?). Soldered to this is a twisted smooth wire and then a base ring.

The base is separately made. It is a circular plate, turned down with a serrate edge visible underneath. “In this plate, in the inside of the beaker, is a cut circle, under which is fitted a print of plique-a-jour enamel, with a design of scrolling foliate stems on a ground of green. […] The enamel is backed by a separate plate underneath it held by a rim with serrated edge and a girdle. The rest of the inside of the goblet is plain.”

The lid has a “machicolated rim and a side stamped with sunk circles, each pierced with a hole”. The side has two girdles above and below a twisted wire. The lower part of the lid has scrolling roses and plique-a-jour paneling. On the inside, these are plain and separated by bands left in the metal. “The top of the cone is pounced with rays. The finial begins with a ring of eight flat-ended bosses alternately decorated with applied leaves (both above and below) and a pounced rosette above. From this rise eight tiny pointed leaves encircling four great leaves enclosing a spike on which was probably set a fruitelet or knob in the form of a precious stone.”

The beaker is compared to a goblet of silver-gilt in the Berry inventory of 1413, decorated in the same manner and probably the same technique. Although the beaker is unmarked and its place of origin a mystery, three countries are considered most likely places of origin: Germany, Flanders, and France.

Raising:

Theophilus. On Divers Arts. Trans. Hawthorne, John G and Smith, Cyril Stanely. New York: Dover Publications, Inc, 1979.

Page 99: Making a small chalice
-Before beginning, find and make center point with compass on balanced sheet of metal
-Make a square projection for fixing on foot later
Page 100:
-When silver is thin enough to bend by hand, draw concentric circles
-inside: center to halfway
-outside: halfway to rim
-round hammer on outside to give depth following circles in a spiral
-medium hammer on round anvil to make narrow on outside following circles in a spiral
-When done, scrape smooth with a file
Page 101
-hammer foot just like the bowl of goblet was hammered
-no projection needed
-make sure to hammer evenly so there is no leaning
-when finished, anneal and then fill with wax.
-hold foot with left hand and a thin punch in your right
Page 102
-”seat a boy next to you with a tiny hammer to strike the punch wherever you put it.”
-file and scrape inside and out
-make a square hold inside the knop, same size as projection
-inside, place round thick piece of silver with similar hole
-burnish bowl and foot, inside and out
-rub with cloth and scraped chalk until shining
-slit projection in four and place in the knop and ring
-hit with punch (sounds very much like how a grommet works)

Cellini, Benvenuto. The Treatises of Benvenuto Cellini on Goldsmithing and Sculpture. Trans. Ashbee, C. R. New York: Dover Publications, Inc, 1967.

Page 85: How to fashion vessels of gold and silver
-trim, plane, and round edges of oblong plate
-beat into a rounded shape
-”hammer from one angle to the other driving the metal well to the center” to look like a cross and then reverse the process outwards
-diameter should exceed that of the future vase by three fingers
-balance the plate to find the center and strike the plate to mark the center on both sides
-strike a circle with a compass
-Follow the circles, hammering “by repeated heating and beating”
-do not lose the center point – continue beating circle until diameter exceeds that of future vase
-use compass again to make concentric circles
Page 86
-”movement of the hammer should be in the form of a spiral and following the concentric circles”
-beat and heat until the silver starts to look like the crown of a hat
-metal should spread equally
-draw metal inwards until it is as deep as your model body needs
-use various stakes and the narrow or broad end of the hammer until equally bellied
-work out imperfections as you go

McCreight, Tim. The Complete Metalsmith. Worcester, Massachusetts: Davis Publications, Inc, 1991.

Page 58: Stretching and Sinking
-stretching is when sheet of metal is forged against a flat surface like an anvil
-as tension increases between hammered spaces and unhammered spaces, the metal domes
-advantages: thick edge, rapid progress, overall size stays the same
-disadvantages: depth is limited by hammer access
-cut a disk: diameter + ½ height
-use 20-16 gauge stock
-make concentric circles using a compass to use as guidelines
-sink metal into a sinking block using a ball faced hammer or mallet
-progress from the inside out
-once at a desired depth, bouge(?) the form over a mushroom stake
-sinking blocks are made of wood, using the end grain

Page 60: Raising
-an ancient technique needing only metal, a hammer, and a form to bend the metal on
-diameter of the starting disk is the sum of the widest and tallest measurements
-find the center on the sheet, draw the right size circle, and cut it out
-file and burnish the edges and then anneal
-if vessel needs a flat bottom, leave the bottom alone. Sink, stretch, or crimp to preference
-progress from the base to the edge is called a course: concentric circles a half inch apart
-if edge flares too much, raise a course or two at mid-height

Page 61:
-as raising continues, top edge will thicken
-exaggerate by tapping edge with cross peen
-planish once form is complete
-planish lower half if, midway, stakes will no longer reach inside.
-straightness of a form is checked by a surface gauge or with pencil
-trim top and file if necessary
-to planish, overlap blows and don't hurry
-planishing works best if hammer and stakes/anvils have a mirror finish
-any smooth faced hammer will do
-12-16oz hammer for quick work, 3-6 oz hammer for finalizing


Soldering:

Theophilus. On Divers Arts. Trans. Hawthorne, John G and Smith, Cyril Stanely. New York: Dover
Publications, Inc, 1979.

Page 106: Casting the handle for the chalice
-with a file and gravers, fit handles to the bowl in their proper place
-make two slots, one above and one below for underlying joints
-fit broad pins into slots on each side of bowl
-fasten pins on the inside of the bowl and solder

Page 107: Soldering silver
-melt silver and copper and file into filings once hardened again
-put filings into quills
-grind fired argol in a pot with water and salt until “thick as lees”
-spread liquid on pins (inside and out) with wooden lath and cover with fillings
-let dry and reapply more thickly
-put in fire until solder melts – wash once cold
-may need to apply many layers
-when firm, file and scrape smooth so the solder is not apparent

Cellini, Benvenuto. The Treatises of Benvenuto Cellini on Goldsmithing and Sculpture. Trans. Ashbee, C. R. New York: Dover Publications, Inc, 1967.

Page 93: Of figures made in silver
-a solder composed of one eighth part of an ounce of copper to one of silver
-fix tubes to the bellows to blow from below the bed of coals
-when the work is aglow, blow the bellows gradually to make the solder run
-use borax...somewhere... Stupid Cellini
-if you need more, use water and a tallow candle to make an ointment and place more solder
Page 94
-if you sprinkle ash instead of water to add fresh solder over the imperfect solder

McCreight, Tim. The Complete Metalsmith. Worcester, Massachusetts: Davis Publications, Inc, 1991.

Page 70: Soldering
-solder introduces an alloy that can flow into spaces of expanded metal when heated
-soft solder is from surface to surface and can not be filed flush, but melts at a third the temperature of other solders
-the amount of zinc in silver solder controls the melting point
-zinc vaporizes when heated
-each time you heat solder it raises the melting point
-burning out the zinc will leave pitted seams

Page 71: Soldering Process
-for a good fit: check for gaps by holding work up to the light
-no grease, finger oils, tape, pickle, buffing compound, pencil marks, etc
-flux is needed for oxygen absorption
-equal heating on all soldered pieces for best results
-solder flows towards heat – it can be drawn -into- a seam via torch position
-use just the right amount so as not to have to remove excess later
-if soldering something enclosed, leave room for steam vents
-metal temperatures are best seen in dimly lit areas

Page 72: Torches and Blocks
-different types of torches can be used (I have a canister type on loan)
-Different types of soldering blocks can be used
-charcoal: can imbed the work but is expensive and messy
-fire brick (I have these!): soft, inexpensive, safe but will crumble when a lot of flux is used
-coiled asbestos: flat and relatively soft but respiratory badness – avoid
-ceramic & synthetics: heat sinks and disagreeable fumes when first heated
-wire nest & pumice: very good for annealing when you don't need flat surfaces
-take care of build up of flux glass
-apply flux in fingers instead of on block
-rub blocks together or sand: wear a respirator!

Page 73: Flux
-fluxes protect the metal from oxidation by being an oxygen magnet
-as oxygen combines with the flux and diminishes the protection, seen as a blue or green tint
-borax: a mineral, used in paste form with water
-handy flux: borax based compound, leaves a tough glassy skin
-battern's: flouride based compound, self pickling, not as oxygen absorbing
-boric acid & alcohol: add the acid to the alcohol until a thin paste, dip work into solution
-prips flux: piece is dipped and then warmed till dry, several applications recommended, waterproof
-cupronil: handy for repair work, preserves finish through heating
-hydrogen peroxide: sparex, peroxide, water – pickle first in sparex, exposure to sunlight weakens solution

Page 74: Soldering Methods
-chip: puts on correct amount of solder, serves as heat indicator
-sweat: more control, out of sight, directs solder flow
-probe: good for difficult solder placement, efficient, good for production work
-wire: advantage of probe without needing to cut solder, control is important
-mud: used in commercial assembly, good for filigree, flux can splatter

Page 75: Pickle
-strong chemical bath to dissolve oxidation and flux residue on the surface of the metal
-always add acid to water, wear PPEs, wash hands, keep baking soda close for spills
-pickle absorbs copper ions
-plating can occur if not careful
-introducing steel will deactivate the pickle
-solutions: ferrous: sparex #1, non-ferrous: sparex #2, sterling: water/sulfuric, gold: nitric, water
-best at 80 degrees, do not boil
-flame types
-neutral: sharp point, gentle hiss, medium blue
-reducing: bushy, deep blue, pulsing, best for soldering
-oxidizing: thin cone, angry hiss, pale lavender, not good for soldering



Lost wax:

Theophilus. On Divers Arts. Trans. Hawthorne, John G and Smith, Cyril Stanely. New York: Dover
Publications, Inc, 1979.

Page 105: Casting the handles for the chalice
-shape handles of wax and carve figures on them
Page 106
-on the top of each handle, place a small bit of wax – rounded at a slight taper and the length of your little finger
-called “the gate” and should be “soldered” on with a hot iron
-vigorously knead clay and carefully cover each handle
-fill all holes of the carving
-when dry, cover again except the top of the gate
-when dry again, do it a third time
-put mold near coals and, once heated, pour out wax
-put molds in fire, turned downwards and leave until red hot
-immediately melt silver and add spanish brass
-stand up molds correctly and pour in the silver

Cellini, Benvenuto. The Treatises of Benvenuto Cellini on Goldsmithing and Sculpture. Trans. Ashbee, C. R. New York: Dover Publications, Inc, 1967.

Page 87: How to fashion vessels of gold and silver
-fashion wax into whatever design you wish for handle or lip
-dry and sift earth an mix it with fine cloth shearings and cows dung sifted
-pound tripoli very fine and make into a pigment
-streak over the wax ornamentation
-also streak over the inlet and vent holes
-let it dry before coating with the clay to the thickness of a knife's back
-apply coats in this manner until a finger thick
-bind it all around with iron bands
-more coats of clay mixed with more cloth shearings
-holding vent holes downwards, melt out wax
Page 88
-remove from where it attached to the vase and fill that area with the clay
-bind with more iron bands
-coat with tripoli mixture
-fire in a brick furnace until dry using charcoal
-place mold into a large receptacle full of sand that is moist but not wet
-when silver is melted, add finely powdered tartar to keep it fresh
-take a piece of linen, folded in four and soaked in olive oil, and place over the tartar that covers the silver
-the rag keeps the silver warm and keeps bits of coal from falling into the mold
Page 89: Another method
-mix brick dust and gesso dust with cold water into a paste
-using a hog sable, paint over the wax model
-put it all on at once: after one coat you can layer the thickened gesso on with a spoon
-bind with fine iron wire weaving it all around
-cake the mold with thickened gesso that wasn't sifted moistened with water
-let the gesso dry in the sun or a warm smoky corner until all moisture is gone
-put over a slow fire to melt wax
-this method is quicker than the previous
Page 90: A third method
-cut wax models into small pieces and powder and clay them and put in troughs
-make lead castings from the molds
-clean the lead castings and work them up to cast them in silver in the same troughs
-this method can be used many more times than a single casting

Vasari, Giorgio. Vasari on Technique. Trans. Maclehose, Louisa S. New York: Dover Pulications, Inc, 1960.

Page 161: The fire-resisting envelope applied over the wax
-using moistened ash, cover the figure with a pain brush until concealed
-mix together fine earth, horse dung, and hair
Page 162
-apply a thin layer carefully and allow it to dry
-continue applying thin layers and allowing them to dry until the thickness of half a span
-gird irons around mold
-make vents that issue upwards
-apply heat to the mold, equally, until all wax has melted out
Page 163
-if you weigh the wax going in, you can know it is all out of the mold by weighing it after melting
-no wax = sharp and beautiful
-wax left behind = ruin the whole cast
-put the mold underground and allow for channels to let the bronze flow through
-saw off the surplus to ensure sharpness
-for every pound of wax, use ten pounds of metal
-two thirds copper, one third brass according to Italian rules

McCreight, Tim. The Complete Metalsmith. Worcester, Massachusetts: Davis Publications, Inc, 1991.

Page 88: Lost Wax Process
-most casting uses the lost wax process developed in ancient egypt
-”When the metalsmiths of ancient cultures first developd this technique they made models of beeswax and coated them with layers of clay. The outer layers were reinforced with straw or linen and the dried assembly was set into an oven to harden. Simultaneously the wax was burned away, leaving a cavity into which molten metal was poured. The clay shell was broken away to retrieve the finished casting.” Hence the term – lost wax.
-make a model of wax and mount it on a sprue
-mount the sprue on a base that fits in a 'flask'
-make an 'investment' free of bubbles, and creamy in conistenc and pour into flask.
-dry -then- heat the investment
-while still warm, pour metal into the mold
-place mold in water after only brief cooling to release the casting


Gilding:

Theophilus. On Divers Arts. Trans. Hawthorne, John G and Smith, Cyril Stanely. New York: Dover
Publications, Inc, 1979.

Page 113: Amalgamating and gilding the handles
-take ground argol and salt and put in a large earthenware dish
-pour in water and newly milled gold and a little mercury
-put on coals and stir with a stick
-have at the ready four large hog bristle brushes bound with iron
-two clean ones to wash the gold and silver
-one wet, one dry, for the gilding
-Dip a linen cloth in the hot mixture and rub all over handles – amalgamating them
-heat over the coals and rub them with a brush wet in the same mixture
-continue heating and rubbing until engravings become white because of the mercury
-this sounds incredibly dangerous >_<
-in places you can't reach, rub with copper gilding tool and thing stick
-on a gilding platter, cut gilding material into tiny pieces
-spread evenly with wet bristles
-pick up piece with tongs with tips wrapped in cloth and put back on the coals
Page 114
-once hot, spread more gold material with the brush until it adheres all over
-do this a second time and a third time
-when the gold begins to dry the third time rub it carefully with a dry brush and heat it again
-rub until it turns pale
-if a blemish appears, put on more amalgam evenly

Cellini, Benvenuto. The Treatises of Benvenuto Cellini on Goldsmithing and Sculpture. Trans. Ashbee, C. R. New York: Dover Publications, Inc, 1967.

Page 95: Of figures made in silver
-When figure is cool, scrub with blanching solution
-tartar, salt, water, and I hate you Cellini. Where did you describe this before?
-scrub until figure turns white with huge hog sable brushes
-put figure in water to wash off solution
-dry figure
-gild the figure... but I wont tell you how, just that it was difficult and looked beautiful after

Enamel:

Theophilus. On Divers Arts. Trans. Hawthorne, John G and Smith, Cyril Stanely. New York: Dover
Publications, Inc, 1979.

Page 126: Setting gems and pearls
-have a flat piece of thin gold for each setting where enamels will go
-once fitted, take them out and cut up strips of somewhat thicker gold and bend them around the strips
-this becomes the border for the enamel
-using the same thickness gold strips, bend and shape designs for the enamel
-arrange pieces in proper place, secure with moistened flour over coals
-solder the thin gold 2-3 times until firmly adhered
-melt samples of each color glass to make sure they will all melt well
-Once red hot, put in a copper pot containing water to immediately burst into fragments
-wash fragments and put in clean shell covered with clean cloth
-place gold plaque on a board and, using a quill, draw up moist glass color
-fill in gold design with as much glass as desired
-fill the plaque completely with color
-put plaque on flat thin iron tray with a short handle
-cover with another piece of iron, concave like a bowl and perforated with holes
-heap charcoal on top and burn strongly
-blow with bellows until holes are red hot
-using a whole wing of a goose, fan the coals
-wait half an hour to uncover it gradually
-wait until holes grow black inside and lift tray out
-put aside until completely cold
-take out enamel and wash it
-fill again and melt as before
-continue until evenly filled

Cellini, Benvenuto. The Treatises of Benvenuto Cellini on Goldsmithing and Sculpture. Trans. Ashbee, C. R. New York: Dover Publications, Inc, 1967.

Page 15: Concerning the art of enameling
-make a plate of silver or gold the size and shape of your work
-create a mixture of ground resin, brick, and wax
-using a compass, outline your design
-using a graver, chisel out the design
-a bas-relief has to be about the depth of two ordinary sheets of paper
Page 16
-red enamel does not stick to silver
-I will not tell how enamels are made.. because I am self righteous and pompous
Page 17
-enameling is much the same as painting
-make sure enamel is fine ground
Page 18
-when enamels are washed and prepared, place in sealed jars to keep them fresh
-fresh water will spoil them
-take a clean piece of paper and chew it
-Cellini has no teeth and couldn't do this
-wash out the paper putty and squeeze dry to use as a sponge for the enamel
Page 19
-be careful painting on the enamels
-once the first layer is on, place piece on an iron plate in a furnace
-once enamel begins to run, quickly pull it out of the fire
-once cool, apply second coat and so on until evenly filled

Vasari, Giorgio. Vasari on Technique. Trans. Maclehose, Louisa S. New York: Dover Pulications, Inc, 1960.

Page 112: Vasari's description of enamel work
-if glass is kept transparent, stained glass window effects are obtained
-similar effects are found in smaller scaled with plique a jour or cloisonne enamel
-transparent pastes are fused into small cells on metal plates
-old examples are very rare due to fragility
Page 113
-the oldest know enamels were different colors separated by ridges of metal which gave lines of design
-pastes that were used were opaque and completely covered over the metal they were laid on
-transparent vitreous pastes fused over a metal ground chased in low relief lets light show through
-transparent enamels are also arranged in apertures so as to show by transmitted light

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Further research used:

Maskell, Alfred. Russian Art and Art Objects in Russia. Henrietta Street: Chapman and Hall, 1884.

The Cooper Museum. Enamel, An Historic Survey to the Present Day. The Cooper Union Museum for the Arts of Decoration: 1954.

Labarte, Jules. Arts of the Middle Ages and Renaissance. London: John Murray, 1855.