Reflectance Spectroscopy for Paper Conservation. National Archives, The Netherlands

Reflectance Spectroscopy is a powerful method for pigments identification even for works of art on paper. We just delivered on Oct 24th a full day Training and a Gorgias Spectrometer system to the Paper Conservation Department of the National Archives of the Netherlands in The Hague.

Read and learn more about Reflectance Spectroscopy and our system, Gorgias, specifically developed for Art and Archaeology professionals.


Interested in Gorgias? Find out how much it cost.  Interested in our tools? Download our 2018 Catalog (360 downloads)

Gorgias – Reflectance Spectroscopy system

We have developed Gorgias, the Reflectance Spectroscopy System for art professionals. It uses a simple software and has plenty of features specifically designed for art examination.
In the analysis of polychrome artworks, among the techniques available in a portable version, Reflectance Spectroscopy (RS) has been established as a powerful one for the identification of pigments. The peculiar advantage of this method with respect to the other spectroscopies most commonly used, such as XRF and Raman, is that the RS equipment can be assembled with relatively low-cost components.Reflectance Spectroscopy shows, for each wavelength, the ratio between the intensity of the reflected light and the incident light, measured with respect to a standard white reference (reflectance). The reflectance spectra provide information useful for the identification of pigments.

In brief

Reflectance Spectroscopy shows, for each wavelength, the ratio between the intensity of the reflected light and the incident light, measured with respect to a standard white reference (reflectance). The reflectance spectra provide information useful for the identification of pigments.

Gorgias, our Reflectance Spectroscopy System designed for the examination of Art and Archaeology.

Gorgias Reflectance Spectroscopy System has 3 components. A professional Reflectance spectrometer, a convenient Reflectance fiber probe, and a compact Light Source.  The Reflectance Spectrometer covers the spectral range 300-1000 nm with 2 nm resolution. It has a new 16 bits electronics for better signal and less noise. You can plug it directly to your laptop with a simple USB cable and start to analyze artworks. Bring it with you for your field projects, it weighs just 430 grams and fits in your palm. At its heart is a linear array featuring 3648 pixels, for high-quality professional reflectance spectra. The system allows measuring practical in any positions thanks to its convenient reflectance fiber probe.

Gorgias, who was him?

We name our tools after famous scientists, artists, and writers that enriched Sicily’s long history.  Gorgias (c. 485 – c. 380 BC) was a Greek sophist and pre-Socratic philosopher and rhetorician who was a native of Leontini in Sicily. Along with Protagoras, he forms the first generation of Sophists. His chief claim to recognition is that he transplanted rhetoric from his native Sicily to Attica. He is considered to be one of the founders of sophism, a movement traditionally associated with philosophy, that emphasizes the practical application of rhetoric toward civic and political life.


What makes Gorgias unique for Art examination?

Mount for Photographic tripods

Only Gorgias has a mount for photographic tripods, just as a camera. How convenient! We work on scaffoldings and on-site, not just in laboratories, so we need to secure our spectrometer while taking the measurements.


Simple software

Acquire and interpret reflectance spectra with our simple custom software for art professionals. It has just a few key buttons to make the workflow fast and easy. Just what we need. The complete software suite with much more functions is also provided with Gorgias. You can switch to one or the other at any time.

Standards for calibration

 Gorgias brings on his top a calibration card and a set of selected historical pigments to double check the system is working correctly.

Free Spectral library of historical and modern pigments 

The software contains the reflectance spectra library of the historical pigments selected in Pigments Checker. You can compare immediately your acquired spectrum with our growing database. It is free and comes with the Gorgias software.


Adapter for Imaging filters 

Gorgias comes with our special adaptor to measure transmittance curves of Imaging filters (technical photography filters and multispectral imaging bandpass filters). The art professionals using Imaging methods for the examination of art and archaeology need this adapter to measure or verify the transmittance of their filters.

CHSOS protective sheet

Use this special sheet to protect the art you are analyzing and still get perfect reflectance spectra.

Technical specifications

Weight: 430 grams
Dimensions: 102 mm x 84 mm x 59 mm
Detector: Toshiba TCD1304DG linear array (no interference pattern)
Detector spectral range: 300 – 1000 nm (100 microns slit)
Pixels: 3648
Pixel size: 8 um x 200 um
Pixel well depth: 100,000 electrons
Signal-to-noise ratio: 400:1 (10000:1 with averaging)
A/D resolution: 16 bit
Fiber optic connector: SMA 905 to 0.22 numerical aperture single-strand optical fiber.
Diffraction order sorting filter: included
Exposure time: 10 us – 60 s
CCD reading time: 14 ms
Power consumption: 100mA @ 5V from USB interface
Onboard memory capacity: 64 spectra
Data transfer speed: 200 ms / 100 ms (2 points binding)
Computer interface: USB 2.0, HID 2.0
Operational system: Windows 10 /Windows 8 / Windows 7 / Vista / XP ; 32/64b
Software: application software, driver,
Hardware: USB cable

Reflection fiber probe
Stainless steel tubing for extra strength. 7 x 600 microns core fibers (6 excitation fibers, 1 collection fiber). It is 1 meter long and it has a 45 degr. adapter for reflectance measures.

Light Source
Dimension (LxWxH): 90 mm x 80 mm x 31 mm
Weight: 70 g
Light source: 10W halogen lamp
Cooling: active, fan, 12 VDC, 25×10 mm
Power: AC-DC transformer, 100 – 240 VAC, Voltage output: 12 VDC
Spectral range: 300 – 1000 nm (halogen lamp)


Q: I am worried about the light level and temperature rise at the surface of the object that you are getting using the 10W halogen source in the Gorgias. I think this can be of some concern, particularly with in-situ analysis of pigments on works on paper. Do you have measurements for light and temperature at the object surface that you could share?
R: The system uses a 10W halogen lamp and, as you observed, this lamp generates heat. Though, the system uses fiber optics for probing and so the hot lamp can be kept conveniently almost 1 meter from the subject. Furthermore, fiber optics do not transfer heat, just the radiation between the near UV and the near IR. This radiation is low because the fiber optics probe just collect a tiny fraction of the radiation emitted by the lamp and deliver it to the sample. We measure it and it is about 200 lux. To understand the magnitude of this value we can consider that standard Office illumination is around 300-500 lux.


Training for Institutions 

Interested to learn our practical methods for art examination? You can invite us to deliver a training program in your location and institution. We have been serving a large community of worldwide institutes (click to see the list).
Contact us for info and quote.


Q. What kind of location would you need to host your classes?
A. We just have few requirements. We need a room that can be made dark. The darker the better.   We need to practice photographic methods such as UVF and IRF which require a dark space. We need power, both 110 (such as the US) or 220 V (as in Europe). Our equipment is designed to work in any Country.

Q. Should we also consider other costs such as materials?
A.  No, our quote will cover everything.

Q. Should we ask participants to bring additional equipment with them?
A. No, we provide the training with our own traveling equipment.

Q. We appreciate your work and our Institution would like to invite you over to learn your methods. We’ll pay travel and lodging. Are you interested?
A. We are sorry, but we cannot accept your offer. CHSOS is a non-governmental initiative and it is sustained only by the community of art professionals and institutions that request our services: the Technical examination of art, Training programs, and our Tools. Indeed, we receive a number of invitations from Universities and Institutions from many Countries which we would really like to visit, but we cannot provide our services without charging our fee.

Q. Should we prepare material (paintings, manuscripts, drawing) to be analyzed during the training program?
A. It is not necessary. We bring our set of test panels which are sufficient to illustrate the methods and practice. On the other hand, we strongly encourage the hosting institution to provide access to selected art or archaeology pieces to be tested during the training. We suggest choosing colored objects since they are the most interesting to be analyzed with our imaging and spectroscopy methods.

Q. We are an institution working mostly on manuscripts conservation and we are interested in your training. Which one is a more effective solution for us? Sending one of our staff to attend your training in Italy or request a training program in our place?
We recommend institutions to request a training program in their location rather than send one of their staff to our training program organized in Italy. Having CHSOS in your institution for the a training program will benefit all of your art professionals staff. Generally, we get contacted by conservation scientists who understand more these scientific techniques. On the other hand, our training programs are aimed at the large audience of art professionals without specific science education, such as conservators, art historians, curators, registrars. Consequently, while the training program is usually requested by the conservation scientists in the institution, the lectures are enjoyed by all the staff with different academic backgrounds.
This training is actually a valid means for the scientists to present and promote the adoption of these scientific methods among their colleagues. Conservators, art historians, curators, they all can see what these techniques can provide to benefit their respective research and conservation workflow. Another important point about requesting training directly in your institution is that we can actually visit your laboratory. We can suggest you specific tools for your particular workflow, we can indicate how to upgrade equipment that you already own, we can test and tune up your tools. The bottom line is that a training program in your institution has a much more assessable impact that just sending one of your staff in Italy to us.



Leave A Comment

Time limit is exhausted. Please reload CAPTCHA.