Core-Formed Vessels

Photo by Christine Brandel

vessels in the Corning Museum of Glass

Okay, so this is not technically glass from the medieval period, but I did say at the outset that sometimes I would veer off into other periods, particularly the early ones. Okay, I sorta said that. But anyway.

So! The Allaire Collection posted recently about one of their core-formed vessels, and that's what inspired my post today. I have a soft spot in my heart for core-forming. It was one of the first techniques I tried to replicate using period materials and processes, way back about seven or so years ago in the pursuit of projects as a member of the SCA. My experiments were not extremely successful, but they were educational, at least.

What is core-forming?

Basically, the technique of core-forming applies to making hollow vessels over a torch flame or furnace by using a shaped form on a stick. This is a particularly ancient technique, actually, since some of the best examples of it come from the Hellenistic and even the Egyptian periods. That is as far back as the 16th century BCE.

In the ancient period, the vessel forms were created using animal dung, straw, clay and water mixed to make a paste, which was then applied to a glassworking rod. The forms were dried completely, and then the shape was refined into what the glassworker wanted it to be. Glass was applied by either trailing the molten glass around the core, much as lampworking is done, or the cores could be dipped into a crucible furnace that holds a 'soup' of molten glass. In some cases, the theory is that layers of frit were applied and fired. Frit is basically crushed glass, and it can be mixed with water to form a paste, which could then be applied to the core.

This photo shows some core material remaining in the vessel:

Photo by Christine Brandel

Vessel in the Corning Museum of Glass

Once the glass was applied to the core, the whole thing would then be fired in the furnace until the glass was uniformly melted and cohesive. The vessel could be decorated, as so many were, with thin lines of glass wound around the vessel and then shaped using a sharp tool.

Common decorations were plain trailed lines, feathered lines, and shifted lines. As a lampworker, I can attest to the skill and steady hands required to place such thin lines around a shape in such a uniform manner, and to manipulate these lines without mangling the vessel or destroying the lines!

Feathered lines look like this:

Photo by Christine Brandel

Vessels in the Corning Museum of Glass

The vessel in the back, on the far left side shows a good example of feathered lines. In the back middle vessel, and the front right vessel, the decoration is more like what is called 'festooning', ribbon-like designs with some curvature.

Once the piece was finished, the cores would be scraped out and the vessel was then ready for use. They were often used to hold kohl, for eye makeup, or for holding other oils, unguents, or small amounts of liquids.

Recently, the Corning Museum of Glass had a post on their blog about core vessels. The museum Explainers, volunteers who talk to visitors about the works in the museum, completed a workshop with hands-on experience in making the cores in the traditional manner, using traditional materials.

There is a Japanese glass artist who makes core-formed vessels. His work is evocative of the ancient vessels we see in museums today, but has a completely modern spin. Beautiful!

I hope you have enjoyed today's foray into ancient, pre-medieval period glassmaking! Below are some further references to explore on the subject, if you'd like more information.

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References:

Taylor, Mark, and Hill, David. Roman Glassmakers. Newsletter 7, January 2005. Web. 2 October 2011. <http://www.romanglassmakers.co.uk/nl7text.htm>

Kritzek, Mandy. "Dung-Core Vessel Making: Explained." Behind The Glass. Corning Museum of Glass. Web. 2 October 2011. <http://behindtheglass.cmog.org/2011/07/14/dung-core-vessel-making-explained/>

The J. Paul Getty Museum. Current Exhibitions: Molten Color. Web. 2 October 2011. < http://www.getty.edu/art/exhibitions/molten_color/>

Nicholson, P. T. and Shaw, I. (eds.) (2000) 'Ancient Egyptian Materials and Technology' Cambridge University Press. Ch.8, 'Glass'.

The Yale Museum

I want to direct your attention to a fantastic resource on the web for ancient art, including plenty of ancient glass. It is the Yale University Art Gallery, and it is located, obviously, at Yale University in New Haven, Connecticut. I've never actually been there, although it's on my list of To-Visit Museums, but I have utilized their online resources, image gallery, and downloadable guide.

Their Ancient Glass: Guide to the Yale Collection is available here, and contains some excellent images and information about glasswork and artifacts in their collection.

I'll be back later this week with a post about mosaic bowls!

Okay, okay...but at least I have some interesting information

I know, I've been particularly lame about posting in this blog since I started it. Truth be told, I haven't had much time or inclination for historical glasswork in the past few months. Oh, I've been periodically been thinking about things, but I've been focused on getting my business, A Hot Piece of Glass, up and running. Now that it is going, I am turning my attention back to some historical works.

For this post, I want to call your attention to two fantastic period glass resources on the web.

One of them is an online magazine called Vidimus. Vidimus means "we have seen", and it refers to the working drawing medieval artisans used to plan a window. In fact, the vidimus is still used today, although it's more often called a cartoon. It serves as a pattern for cutting and placing glass pieces to form the window. In the medieval period, windows were not made entirely by one person. There were the people who actually made the glass sheets (a glassblower), someone who designed the window and drew the vidimus, and other people who actually cut and assembled the window. The glass painters would do the detail paint work on the window before it was installed by the folks responsible for that aspect of creation.

The other fantastic resource is the CVMA, or Corpus Vitrearum Medii Aevi. This is an organization of twelve countries that collectively are involved in preservation and research of historical glass. The link is to the site in Great Britain, which is the one I use the most, but links to German and Italian sites of the CVMA are here. One of the benefits of the Great Britain site is that is has archived a zillion photographs of period glass, some of which are pieces that are either photographed close-up, or look as though they are scanned and then uploaded. So, you get a really good look at some really important works. The search function is indispensable for research, as you can search the picture archive by region, CVMA archive number, type, period or site. I love it. It's where I usually start when I am thinking about a new panel project.

All right, I think that is enough for now. What resources do you use, which are your favorites?