The Great London [Search results for artwork] 

A painting hanging on the wall in an art gallery tells one story. What lies beneath its surface may tell quite another.

Often in a Rembrandt, a Vermeer, a Leonardo, a Van Eyck, or any other great masterpiece of western art, the layers of paint are covered with varnish, sometimes several coats applied at different times over their history. The varnish was originally applied to protect the paint underneath and make the colors appear more vivid, but over the centuries it can degrade. Conservators carefully clean off the old varnish and replace it with new, but to do this safely it is useful to understand the materials and structure of the painting beneath the surface. Conservation scientists can glean this information by analyzing the hidden layers of paint and varnish.

Now, researchers from Nottingham Trent University's School of Science and Technology have partnered with the National Gallery in London to develop an instrument capable of non-invasively capturing subsurface details from artwork at a high resolution. Their setup, published in an Optics Express paper, will allow conservators and conservation scientists to more effectively peek beneath the surface of paintings and artifacts to learn not only how the artist built up the original composition, but also what coatings have been applied to it over the years.

Traditionally, analyzing the layers of a painting requires taking a very small physical sample -- usually around a quarter of a millimeter across -- to view under a microscope. The technique provides a cross-section of the painting's layers, which can be imaged at high resolution and analyzed to gain detailed information on the chemical composition of the paint, but does involve removing some original paint, even if only a very tiny amount. When studying valuable masterpieces, conservation scientists must therefore sample very selectively from already-damaged areas, often only taking a few minute samples from a large canvas.

More recently, researchers have begun to use non-invasive imaging techniques to study paintings and other historical artifacts. For example, Optical Coherence Tomography (OCT) was originally developed for medical imaging but has also been applied to art conservation. Because it uses a beam of light to scan the intact painting without removing physical samples, OCT allows researchers to analyze the painting more extensively. However, the spatial resolution of commercially-available OCT setups is not high enough to fully map the fine layers of paint and varnish.

The Nottingham Trent University researchers gave OCT an upgrade. "We're trying to see how far we can go with non-invasive techniques. We wanted to reach the kind of resolution that conventional destructive techniques have reached," explained Haida Liang, who led the project.

In OCT, a beam of light is split: half is directed towards the sample, and the other half is sent to a reference mirror. The light scatters off both of these surfaces. By measuring the combined signal, which effectively compares the returned light from the sample versus the reference, the apparatus can determine how far into the sample the light penetrated. By repeating this procedure many times across an area, researchers can build up a cross-sectional map of the painting.

Liang and her colleagues used a broadband laser-like light source -- a concentrated beam of light containing a wide range of frequencies. The wider frequency range allows for more precise data collection, but such light sources were not commercially available until recently.

Along with a few other modifications, the addition of the broadband light source enabled the apparatus to scan the painting at a higher resolution. When tested on a late 16th-century copy of a Raphael painting, housed at the National Gallery in London, it performed as well as traditional invasive imaging techniques.

"We are able to not only match the resolution but also to see some of the layer structures with better contrast. That's because OCT is particularly sensitive to changes in refractive index," said Liang. In some places, the ultra-high resolution OCT setup identified varnish layers that were almost indistinguishable from each other under the microscope.

Eventually, the researchers plan to make their instrument available to other art institutions. It could also be useful for analyzing historical manuscripts, which cannot be physically sampled in the same way that paintings can.

In a parallel paper recently published in Optics Express, the researchers also improved the depth into the painting that their apparatus can scan. The two goals are somewhat at odds: using a longer wavelength light source could enhance the penetration depth, but shorter wavelength light (as used in their current setup) provides the best resolution.

"The next challenge is perhaps to be able to do that in one instrument, as well as to extract chemical information from different layers," said Liang.

Source: The Optical Society [April 13, 2015]

Wire Tree Sculpture

A wire tree sculpture is a great way to spruce up a room without having the pain and mess of having a live tree in the house. The wire tree sculptures are good for models for a larger project and for the full-scale item itself. These are often created by artists because you are able to be very creative at a reasonable price and with a very limited amount of time. A tree is one of the most interesting things that can be made as a model with wire. If the artists has a good background with sketching trees, this will help because the knowledge of the proportions of trees will be helpful in the sculpting process.

Choosing The Wire

The wire that is chosen for the artistic piece is going to set the mood for your tree. If you want the tree to have a lighter, more airy feeling, a smaller gauge wire is best, but if you want something larger and more defined, a thicker, heavier wire will look much better. These kinds of wire can be purchased at craft stores, big retailers, home improvement stores or at Bonsai Tree Gardener. They are sold on spools, so make sure you get the correct amount, and choose between the common types of metal, steel or copper. Copper will be more bendable, but it will remain copper-colored, however steel isn’t as pliable but will be able to be colored.

Tools Required

You will also need to choose which tools you want to use for the production of your tree. Your hands will serve for most of the detail work; however a pair of needle nose pliers will also be helpful. The wire will be able to be bent without problem in most cases, but for the tiny curls and bending the pliers will be helpful. If you choose to use a similar gauge to coat hangers, this will most assuredly need at least one pair of pliers for bending.

Creating Your Sculpture

After you have purchased all of the wire and have planned out your tree and gathered your tools, you are ready to create your new piece of art. The base should be created first since it is the trunk of the tree. An easy way to do this is to take the pliers and bend the wire so it zigzags up and down vertically to create the trunk, and splay the bottom out while flattening the individual wires just like roots.

This will allow the tree to sit up on its own. You can also spiral the wire from the bottom to the top, both of these ideas will give you a realistic-looking tree while still being rather artistic. The leaves and the top of the tree in general can either be contoured or you can add an additional piece and connect them. If the artwork has leaves, make sure to vary the position, size, and area that the leaves are placed. Make sure the area where the leaves are looks full as well; continue adding leaves until it looks desirable to you. Using coat-hanger-like wire will result in it being much more difficult to do the top of the tree since it does not end as easily as the more rounded, smaller wire.

For more instructions on how to create or to purchase a wire tree sculpture, visit Wire Tree Sculpture | Bonsai Tree Gardener — The #1 Guide To Bonsai Trees on the web.