Intaglio-Gems-art - 6/17/10
"Intaglio: Sculpture in Reverse (or: Hey! My jewelry does impressions!)" by Lady Rekon of Saaremaa.
This article was submitted to me by the author for inclusion in this set of files, called Stefan's Florilegium.
These files are available on the Internet at: http://www.florilegium.org
Copyright to the contents of this file remains with the author or translator.
While the author will likely give permission for this work to be reprinted in SCA type publications, please check with the author first or check for any permissions granted at the end of this file.
Mark S. Harris...AKA:..Stefan li Rous
stefan at florilegium.org
Intaglio: Sculpture in Reverse (or: Hey! My jewelry does impressions!)
by Lady Rekon of Saaremaa
Barony of Dreiburgen, Kingdom of Caid
Intaglio is reversed carving, done in negative space, such that the finished carving, if pressed into wax or another soft substance creates a relief sculpture in miniature. Intaglio stones were often set into jewelry and used as personal seals. Skilled carvers of intaglio were rare enough that intaglio stones would often be scavenged from older pieces of jewelry and re-set for later owners, and the carvings were desirable enough that even simple 'scratch-carvings' were made and sold in great numbers. While agates and other hard stones were much desired for them, other, easier to carve stones, including lapis lazuli and jasper, were also used.
Period tools for doing this kind of work would have included rasps or files, as well as abrasive powders such as emery powder; however, much of the work would have been done using a sort of lathe-mounted drill, powered by a bow-drill or a kickwheel (as a potters' wheel is powered). The drill bits would have been made of copper and impregnated with abrasive powder, and were used with water or oil to prevent heating and possible cracking of the stone. It was very time-consuming, detailed work, and using hand tools it is difficult to see results quickly, as well as being in some cases hard to control, as pressure sufficient to carve is also close to the pressure that causes the tools to slip, scratching the surface and possibly damaging the fine work of the design.
My methods differ from period in that I use diamond bits on a rotary tool, which make the work somewhat faster and easier than it would have been with period tools. I do not own truly period tools for this work. I pencil in the design on the face of the stone I will work. Then I begin by taking out large sections of the design with my coarser diamond bits, very slowly and carefully to avoid slipping. After that, most of the work involves scraping away material until the design is incised deeply and the smaller details are clear. To finish, I use fabric buffing wheels with cerium oxide rather than emery powder.
Intaglios can be portraits, depictions of heroes or deities, badges, or devices, or any image the carver can make. A set intaglio stone is personalized custom jewelry which is simultaneously a work of art and a functional tool.
These are some of my early pieces: a set of stones presented at Estrella War to the Royals of Caid. The lapis ones are the Royal seals, while the smaller blackstone ones are their own personal devices.
How I do it – tips and tricks
First of all, the stone you choose to carve is important. Jasper, with its wide variety of colors and patterns, smooth texture, and relative ease of carving, is ideal as a beginner stone, and was very commonly used in period, as was serpentine, which is similarly easy to work. Hematite also carves easily, and with its metallic appearance gives the impression it is not stone at all. Lapis lazuli is nearly as easy, but the gold flecks (actually pyrite inclusions) are far harder than the blue and occasional white parts of the stone, which can make carving difficult. Malachite is easy too, but it is poisonous if inhaled or ingested in powdered form, so please use adequate protection and clean up thoroughly afterward. Jet is quite easy to carve, even with hand tools, as is amber, but amber is very temperature-sensitive, and can shatter if used to make an impression in hot wax. Carve it with hand tools or using a coolant like water, and do not use it for seals.
More difficult, though beautiful, stones include agates, onyx, carnelian (very popular in period), jade, obsidian, and the entire quartz family (everything from rock crystal to amethyst and citrine). These were also used in period. The main problem is that these are harder stones, and once polished, their surfaces are slick, causing finer grit tools to slip. Use coarser bits to start the engraving, then move to a finer grit to do the finer work, and the slippage problem should be solved. The other problem is that these stones are far less forgiving of the heat generated by the engraving process, and tend to crack or even shatter. Like amber, a coolant (water is fine most of the time) needs to be used to protect the stone.
Most difficult are the truly hard gemstones, like rubies. They take more time, and you can wear out tools carving them. However, they were used in period, and if you really want to, you can use them too. I would recommend using a stronger machine than a Dremel, though, as the resistance they put up to being cut is pretty tough. Foredom rotary tools are, by reputation, the best choice for this work.
I use a foam pad to rest the stone on so that it won't slip under the tool. I still have to hold it with my fingers, but it is much easier to do against the pad than a hard surface. It also absorbs much of the vibration from the tool, which may prevent cracks. To test the carving and see where more work is needed, I use Silly Putty. No, it isn't period either, but it won't damage the stone and makes a very detailed impression so that you can see exactly what the carving would do on wax. Start with the general outline of your design, then dig in for the high areas (muscles, eyebrows, charges on devices) and do more shallow work for areas that will be more recessed in the final impression (backgrounds, eyes).
Danger! Danger! Don't undercut!
Ok ok ok BAD!
These are cross-sections of intaglios (badly drawn, but you'll get the point). Gradual slopes and straight-sided or curving edges to your carvings are fine and will make nice, clear impressions, but if you carve out even a little further to the side and leave an overhang, the wax will catch in the undercut and break the seal when you remove the stone. When you make your Silly Putty impression, beware undercuts if the putty seems to be hard to remove or pulls like taffy from part of your design.
Really, any rotary tool with interchangeable bits will be fine for most intaglio work. It will be more comfortable for you if you can find one with a flexible shaft attachment, so that your hand has less strain on it, and can do finer details. The diamond bits can be inexpensive or horribly overpriced. If you have a local rockhound club, try contacting them and asking about upcoming gem and mineral shows. There will usually be a vendor or two there (often in some back corner) who will have all the lovely bits you could ever want for about $6 a set, and will probably also have bags of cerium oxide polishing compound. Watch out that the bits are the right diameter for your tool, or invest a few dollars in interchangeable collets (the little part that 'catches' the bits) for different diameter bits.
Remember: Everything is Backwards! Work in mirror images and all will be well. May the Force be with you.
Boardman, John. Intaglios and Rings. Thames & Hudson Ltd. 1975.
Gregorietti, Guido. Jewelry: History & Technique from the Egyptians to the Present. Chartwell Books, 1978.
Heilbrunn Timeline of Art History: Metropolitan Museum of Art
http://www.metmuseum.org/toah/hi/hi_pobo.htm (examples of intaglio)
Henig, Martin. The Veneration of Heroes in the Roman Army: The Evidence of Engraved Gemstones. Britannia, Vol. 1, pp. 249-265. Society for the Promotion of Roman Studies.
Istituto Geografico De Agostini. Color Treasury of Gems and Jewels. Crescent Books, 1971.
Renton, Edward. Intaglio Engravings: Past and Present. George Bell and Sons, London, 1896.
Spier, Jeffrey. Medieval Byzantine Magical Amulets and Their Tradition. Journal of the Warburg and Courtald Institutes, Vol. 56 (1993). The Warburg Institute.
Wixom, William D., et al. Medieval Europe. The Metropolitan Museum of Art Bulletin, New Series, Vol. 50, No. 2, Recent Acquisitions: A Selection 1991-1992 (Autumn, 1992), pp. 3 + 18-23. The Metropolitan Museum of Art.
Copyright 2010 by Kirsten M. O'Brien. <kirstenmae at gmail.com>. Permission is granted for republication in SCA-related publications, provided the author is credited. Addresses change, but a reasonable attempt should be made to ensure that the author is notified of the publication and if possible receives a copy.
If this article is reprinted in a publication, I would appreciate a notice in the publication that you found this article in the Florilegium. I would also appreciate an email to myself, so that I can track which articles are being reprinted. Thanks. -Stefan.