Sunday, September 27, 2015

Chasing and Repoussé: Bumpity Bits, and How to Achieve Them

Chasing and Repoussé: Bumpity Bits, and how to Achieve them!
(Of Repoussé, Chasing, and Related Methods)
                                                                                By:
                                                                THL Muin maqq Minain
                                                                (mda: Donald Downie)                                 


(Safety Note: This process involves HEAT. Heat can be dangerous to the unwary, incautious, and stupid. If you think you may fall into any of these categories, stop reading HERE. The handsome and intelligent author of this work has no interest in your harming of yourself, nor of others. )


A Brief Pause for Terminology
Repoussé or repoussage - (French pronunciation: [ʁəpuse]; [ʁəpusaʒ]  is a cold worked metalworking technique in which a malleable metal is ornamentally formed by hammering from the reverse side to create a design in low relief.
    The word repoussé is French and means "pushed up", ultimately from Latin: pulsare, which means "to push". Repoussage is the noun to refer to the technique, with repoussé being an adjective referring to a piece to which the technique has been applied (e.g. "repoussé work", "repoussé piece"). 
Chasing - comes from the French word chasser meaning to drive out, or to chase around, which is what the artists are doing as they "chase" the forms on their metal in order to create their final design. (RUN, YOU FOOLS! It's chasing you! It's in the house! AAAAAHHHGGGG!!!)
Annealing - in metallurgy and related fields, is a heat treatment of the material that alters the physical and sometimes chemical properties of these materials. This is to increase its ductility and to make it more workable. All metal is crystalline in structure, and the growth and formation of the internal crystal lattice is important to bear in mind while working with metal. Annealing involves heating a material to above its chemically stable, solid state temperature, maintaining a suitable temperature, and then cooling. Annealing can induce ductility, soften material, relieve internal stresses, refine the structure by making it homogeneous, and improve cold working properties.
Tuning - in relation to this subject covers the frustrating task of taking a basic pitch compound, and adjusting the working properties, to suit the artists’ needs.
Pitch bowl -usually a cast iron bowl which sits on a bag stuffed with sand, or on a wood, or a coil of rope, or rubber ring specifically made for this purpose. The bowl holds the pitch, which holds the work.
Pitch Board - a flat board, or surface into witch a shallow depression has been cut to allow for pitch to occupy, the pitch board then serves as a platform for repoussé and chasing.
Chasing Hammer, or Hammer - a specific variety of leverage tool, in the Hammer family. *

*(Note: the Hammer is the greatest single invention mankind has ever produced, which has lead to the rise of civilization. Possibly the gift of Gods or aliens to primitive man, the hammer is a singular tool of many forms and uses for which we should be truly grateful. Truly….No. really. Not just any monkey could come up with something like this…)

http://francesandrews.files.wordpress.com/2011/05/img_1761.jpg

There are few techniques that offer the variety of expression while still being relatively economical, as the materials and tools for this process are easily within most budgets. This technique allows for high relief artistry, while offering the economical use of metal, conserving weight in the final piece not offered by casting, and diverse expression of final product. Chasing is often referred to as the opposite technique to repoussé, and the two are used in combination to create a finished piece. Chasing and Repoussé should always be thought of, however, as the two halves of one whole process. 
It is also known, by some, as embossing, though that is a gross oversimplification of technique, and should not be taken seriously. By anyone. Ever. Stamping and Punching are also not to be confused with the methods of Chasing and Repoussé, as they just mark the surface of the metal, without raising nor sinking the metal’s form to create complex planes in the Z Axis. Baking, Surfing, and Tennis are also not an appropriate comparisons to make, nor terms to use...no...really...just sit down...you're so pretty...
     While repoussé is used to work on the reverse of the metal to form a raised design on the front, chasing is used to refine the design on the front of the work by sinking the metal. The term chasing is derived from the noun "chase", which refers to a groove, furrow, channel or indentation. The adjectival form is "chased work".
     The techniques of repoussé and chasing utilize the plasticity of metal, forming shapes by degrees. There is no loss of metal in the process, as it is stretched locally and the surface remains a contiguous and continuous whole. The process is relatively slow, but a maximum of form is achieved, with one continuous surface of sheet metal of essentially the same thickness. Direct contact of the tools used is usually visible in the result, a condition not always apparent in other techniques, where all evidence of the working method is eliminated.

     It can take some time to create jewelry or art using repoussé and chasing techniques, although with practice, complex and delicate pieces can be made which would be virtually impossible to complete using any other method, especially when considerations such as weight are taken into account.
     There is an abundance different metals you can use for chasing and repoussé work, such as drawn steel, a variety of bronzes, copper, gold, silver and even pewter.
     The process of chasing / repoussé can be an arduous process, due to the repetition of a number of time-consuming stages:
    The first step is the preparation of the metal by annealing; cleaning to remove the pitch between annealing and work; setting up; and careful work with punches. This process is typically repeated many times during the creation of a the final piece. 
One method of repoussé and chasing is to place a thin sheet of metal on a bowl of chasers pitch. This chasers pitch can be pine rosin–based that can be kept slightly soft with a heat gun or a torch for relief work and hardens when cooled for chasing/planishing work. (Uses of heat guns are MODERN CONTRIVANCES, and done solely for the safety of the modern crafter and their unsuspecting families. In period, the pitch bowl and working surface were kept warm, and thus pliable, by working them in proximity to a large heat source such as a forge. This is not a tenable option for modern artists due to expense and safety.) 
The pitch can become extremely soft or liquefied when heated too much, becoming somewhat of a burn hazard. (By “somewhat” I mean “VERY”) It is not recommended, nor necessary to heat the pitch to this degree. See references to such things as “flaming pitch”, “Johnny Tremain”, “castle defenses”…and so on.
     The purpose of using pitch is to provide a solid base, a mutable anvil, on which to work, whilst allowing the metal to be pushed out and shaped without obstruction. The pitch is best worked on in a pitch bowl or "pitch board." The traditional pitch bowl is a cast iron bowl which sits on a bag stuffed with sand, or on a wood or rubber ring specifically made for this purpose. This allows for greater stability, rotation and angling. The pitch is heated using a variety of methods. If the pitch is too hard, the metal will be thinned. If it is too soft, you have very little control over the form, and the metal will move around the surface, or be sunk beneath the too liquid pitch. A good medium grade chasers pitch, formulated specifically for jewelers and metalsmiths, works well because it softens enough to allow for satisfactory relief and cools to a firmness that is sufficient for chasing, planishing and detail work.
Steel tools are used to work the metal. A "liner" is a steel tool/punch with a very thin, slightly rounded end, which is used to create the initial lines on the metal. The liner is hit on the (back) end with a chasing hammer, pushing a thin line of metal into the pitch. The side facing up will consequently be the front of the piece. Once all the lines have been chased, the metal is then turned over on the pitch, and repoussé technique is then applied, using other various steel punches/tools to push the metal so that it is raised on the front of the finished piece.
Once the repoussé is done - the design raised, the piece is inverted, and the voids are filled with warm pitch to help maintain its shape. The pitch should be allowed to set in the voids and cool before the piece is turned over and placed back on the pitch. Once the piece of metal is turned over and then chased, in that the details are refined and brought out. The design is worked many times, with numerous tools, before the final result is achieved. 
Every time the metal is removed from the pitch bowl, it needs to be cleaned and re-annealed. Turpentine is used to remove the pitch, and a blow torch can also be used to burn it from the metal surface.
When working with the pitch, make sure you are working with gloves, safety glasses and good ventilation and as always, when working with any type of open flame, make sure there is an appropriate fire extinguisher close by.



(Safety Note: This process involves HEAT. Heat can be dangerous to the unwary, incautious, and stupid. If you think you may fall into any of these categories, then stop reading HERE. The author of this work has no interest in you harming yourself, nor others. Seriously. Neither the author’s good intentions, nor inherent awesomeness cannot save you from yourself. If you are the type of person confused by things like scissors…paper…bright lights…hammers…by all that is Holy, stop now!)


               Historical References

Some o the oldest materials used by man have had a marked and telling effect upon entire eras, both in cultural development and artistic expression. Most people are aware of the eras named for metals, that is: The Bronze Age and the Iron Age’ though there were shorter, lesser known ages, such as the Copper Age.
The Copper Age, dating back to 8000bce is known for a proliferation of copper bowls, weapons, tools and vessels made using the repoussé method. Items recognized as specifically religious purpose date to 6000bce, and were of Sumerian make, and even introduce the world’s first examples of gold work.

The techniques of repoussé date from Antiquity and have been used widely with copper, bronze, tin, pewter, iron, steel, gold, and silver for fine detailed work and with copper, tin, and bronze for larger sculptures. Classical pieces using this technique include the bronze Greek armor plates from 400bce.
During the 3000bce, in the Middle East, a variety of semi-mass production methods were introduced to avoid repetitive free-hand work. With the simplest technique, sheet gold could be pressed into designs carved in intaglio in stone, bone, metal or even materials such as jet. The gold could be worked into the designs with wood tools or, more commonly, by hammering a wax or lead "force" over it.
The alternative to pressing gold sheet into a die is to work it over a design in cameo relief. Here the detail would be greater on the back of the final design, so some final chasing from the front was often carried out to sharpen the detail. The use of patterned punches dates back to the first half of the 2nd millennium BCE, if not far earlier. The simplest patterned punches were produced by loops or scrolls of wire. By Hellenistic times, combined punches and dies were in use.
In 1400 BC, the Egyptian Amarna period, resin and mud for repoussé backing was in use. In 400 BC, the Greeks were using Beeswax for filler in repoussé.
Repoussé and chasing are commonly used in India to create objects such as water vessels. These vessels are generally made using sheets of copper or silver.
During the Hopewell and Mississippian periods of the American Southeast and Midwest goods of repoussé copper were fashioned as ritual regalia and eventually used in prestige burials. Examples have been found with many S.E.C.C. designs such as Bi-lobed arrow motif headdresses and falcon dancer plaques. Although examples have been found in a widely scattered area (Spiro, Oklahoma, Etowah, Georgia, and Moundville, Alabama), most are in what is known as the Braden Style, thought to have originated at the Cahokia Site in Collinsville, Illinois. Several copper workshops discovered during excavations of Mound 34 at Cahokia are the only known Mississippian culture copper workshops.




(Safety Note: This process involves HEAT. Heat can be dangerous to the unwary, incautious, and stupid. If you think you may fall into any of these categories, stop reading HERE. I’m begging you! Both materials and thinking are involved ahead. )







                                                                Materials and Tools

Pitch!

The traditional working surface is “Chaser's Pitch”, commonly called “Pitch”, which is usually a composition combining three substances: pure pitch, a filler (or stiffener), and an emollient (softening medium). While an artist can work with straight, un-adulterated, Pitch, there are a number of different recipes for making chaser's pitch. And the method of turning pitch into “Pitch” is called “Tuning”. Many recipes for tuning exist, and are dependent upon the variety of options in materials, as well as intended use of the Pitch.

Some Common recipes include:

1.
·         16 parts pitch
·         20 parts plaster of Paris
·         4 parts resin
·         1 part tallow
In this recipe, “parts” are measured by weight.
The pitch is heated until flowingly liquid. WARNING! DO NOT LET IT BOIL!!! Plaster of Paris is added a small amount at a time. Resin and tallow are then mixed in.

2.    6 parts chaser's pitch,
      8 parts plaster of Paris or brick dust,
1 part linseed oil or tallow.
Source: Metalworking Techniques for Craftsmen by Oppi Untracht. 

3.    4 parts roofing tar (the kind roofers melt in tar kettles),
3 parts pumice powder,
1 part turpentine,
1 part mineral oil.
Melt tar in pan, stir in turpentine, add pumice. Ladle out enough to fill the bottom third of your pitch bowl, and then adjust the amount of linseed oil to the bowl to get desired viscosity. 


4.    6 Parts Pitch
8 Parts Plaster of Paris
1 Part Linseed oil or mineral oil
(Whenever starting with warm pitch, mix in other ingredients slowly. No Boiling, burning, nor splashing! Dear Gods! This isn't pudding!! Put down that whisk!!!)

There is a flexible pitch used by chasers referred to as Swedish pitch, which has Pitch + Emollient. Roughly 20/1 mixed proportions.
There are other pitch choices, with two very popular choices being Red (or sometimes referred to as brown) German Pitch and a versatile medium (grade/hardness) dark green Chasers Pitch. There is also a Black Pitch.
The different pitches are used preferentially and according to the type of chasing and repoussé work being done, and the experience of the artist involved.
Pitch softens in warm weather; you will have to vary the proportions with seasonal changes.
This pitch material can be re-used indefinitely if used and stored properly and responsibly. Over heating will burn the pitch, and make it unusable. (Shame...a thousand years, shame!)

Traditional sources site the use of "Pitch", or "Shipwrights' Pitch". Modern jewelers, on the whole, cannot afford the safety nor the expense of extracting the pitch themselves, and buy pitch pre-made from jewelers supply sources. 

As a note: I have attempted to extract Birch Tar myself for various projects (Leather working, blade making, and repoussé work. Northern European peoples including the Finns and the Rus used birch tar for many applications in period. While delightfully aromatic, it is difficult to extract in quantity, and does not tune well for repoussé. 

(Note: There are several brands of “Pre-Tuned” Pitches, ready to be used right from the can. I, personally, have never found them quite to my liking. I end up tuning them anyway. Several other experienced jewels of my acquaintance report the same. Using modern pre-made pitch rather than refining my own pitch is due to health concerns and lack of wealth. I don't own a forest...but, do continue to have a family. Their safety is paramount.)

Once the pitch is in the bowl to your satisfaction, you will need to seat the metal on which you are working into the surface of the pitch. Warm pitch will take the metal, and hold it securely. HOT pitch will make the metal sink deeply.
Now that you have chosen your design, transfer it to the metal surface via your favorite method, be it marker, chalk, metal scribe, or gluing a drawing done on paper to the metal.

Begin by using a narrow bladed chasing tool to push the lines deeply and methodically into the surface of the metal by tapping the end of the tool with the chasing hammer.

Once the complete image has been transferred to the metal surface, begin using the other chasing tools to add internal detail to the design.

When you have worked the entire design to your satisfaction, reheat the surface of the pitch bowl, and remove the metal. The metal will now need to be annealed and cleaned.

The newly clean and softened metal is now reinserted onto the surface of the pitch, placing the side you have already worked down, so that you may now work the back side of the design.

Repeat these processes until you are happy with your design. With each flip of the metal, you will find your design inflate into more, and deeper dimension. 

Finally happy with your design’s form and level of detail, you now may either stop with a final removing of the work from the pitch, cleaning the piece, and polishing. Filing and sanding can be done at your leisure.



https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQv83PNT42a98P6dfJSe_4_mP7T2Gzv7UoTBbU5i7UOqVc081efEC80oMMOo_fxBIrIe9uenQhHFNuR82kqT1lxwSWq77zxKK-QbgE4ceXHGVYR7eGo5S9sI16Xs_Kkxwetr0UzpnGaUE/s1600/DSC08974.JPG

New Photo of full set of tools
Chasing and Repoussé tools come in a variety of shapes, lengths, and widths. Most experienced artists will make their own tools, and constantly customize their selection and specifications.





                                Extant Examples


Gundestrup Cauldron (Arguably the most recognized piece of Chasing and Repoussé)
·         http://upload.wikimedia.org/wikipedia/commons/thumb/e/e2/Detail_2_from_Gundestrupkarret.jpg/180px-Detail_2_from_Gundestrupkarret.jpg
Exterior plate f

·         http://upload.wikimedia.org/wikipedia/commons/thumb/6/69/Gundestrup_antlered_figure.jpg/180px-Gundestrup_antlered_figure.jpg
Detail from interior plate A

·         http://upload.wikimedia.org/wikipedia/commons/thumb/3/30/Gundestrup_C.jpg/180px-Gundestrup_C.jpg
Interior plate C

·         http://upload.wikimedia.org/wikipedia/commons/thumb/d/d9/Gundestrupkarret3.jpg/180px-Gundestrupkarret3.jpg
Interior plate E




http://oi.uchicago.edu/OI/IRAQ/SLIDESHOW/0.jpg                                                       
Mesopotamia, Royal Cemetary at Ur, Gold Helmet of King Meskalamdug, c. 2400 BCE Assyrian Gold

https://33.media.tumblr.com/5333fce753afbf3e3c81341c93ea3ec4/tumblr_n2o34iakOq1rgfuxjo1_500.jpg


Winged Bull Mount, c. 15th-10th century BC
A repoussé gold foil mount in the form of an advancing winged bull with curved horns, gaping mouth, elliptical ear, thick trunk, broad wing and curled tail; on the reverse a gold attachment loop.
At its peak, the Assyrian empire stretched from Cyprus in the Mediterranean Sea to Persia (Iran), and from the Caucasus Mountains (Armenia, Georgia, Azerbaijan) to the Arabian Peninsula and Egypt. Assyria is named for its original capital, the ancient city of Aššur (aka Ashur) which dates to c. 2600 BC (located in what is now the Saladin Province of northern Iraq), originally one of a number of Akkadian city states in Mesopotamia.

A copper repoussé mask of a Shaivite deity  A COPPER REPOUSSÉ MASK OF A SHAIVITE DEITY

NEPAL, 17TH/18TH CENTURY

http://upload.wikimedia.org/wikipedia/commons/thumb/8/85/Byzantine_-_Chalice_with_Apostles_Venerating_the_Cross_-_Walters_57636_-_Profile.jpg/220px-Byzantine_-_Chalice_with_Apostles_Venerating_the_Cross_-_Walters_57636_-_Profile.jpgOne of twenty-three silver altar vessels believed to have been found in the Syrian village of Kurin. Silver repoussé, partial gilt. The Walters Art Museum

http://upload.wikimedia.org/wikipedia/commons/8/86/16th_Century_Tibet_repousse.jpg Gilt copper repoussé from Tibet, 16th century

http://upload.wikimedia.org/wikipedia/commons/thumb/9/98/Mildenhall_treasure_great_dish_british_museum.JPG/220px-Mildenhall_treasure_great_dish_british_museum.JPG
The Great Dish, or Great Plate of Bacchus, from the Roman Mildenhall Treasure


1.     "Chalice with Apostles Venerating the Cross". The Walters Art Museum.
2.    Power, Susan (2004). Early Art of the Southeastern Indians-Feathered Serpents and Winged Beings. University of Georgia Press. ISBN 0-8203-2501-5.
3.     F. Kent Reilly and James Garber, ed. (2004). Ancient Objects and Sacred Realms. University of Texas Press. ISBN 978-0-292-71347-5.
4.     Townsend, Richard F. (2004). Hero, Hawk, and Open Hand. Yale University Press. ISBN 0-300-10601-7.
5.     Pawlaczyk, George (Feb 16, 2010), Copper men: Archaeologists uncover Stone Age copper workshop near Monk's Mound, retrieved 2010-11-08
6.     Kelly, John E.; Kelly, Lucretia S.; Brown, James (2009). Summary of 2008 Field Excavations to Locate the Copper Workshop in the Mound 34 Area(Technical report). Central Mississippi Valley Archaeological Research Institute.
7.     Bowie, Hamish (1977). Jewelry Making. Chicago: Henry Regnery Company. p. 36. ISBN 0-8092-8084-1.
8.    Finegold, Rupert, and Seitz, William, (1983) Silver-Smithing, Krause Publications, ISBN 0-8019-7232-9




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