Assessing the light fastness of 16th century Indian paintings (Michela Rampa)

Next in our British Science Week 2018 series, Michela Rampa talks about her student placement at The British Museum, analysing colours in 16th century Indian paintings and assessing light sensitivity. Find out more at The British Museum’s British Science Week event on Saturday 17 March.

Hello, my name is Michela Rampa. I am a student from the University of Rome, La Sapienza, in Italy where I am studying to become a museum scientist. I am currently doing a student placement at The British Museum for my final dissertation. What a fantastic opportunity!

At The British Museum I am based in the Scientific Research Department but also regularly meet with conservators. I am learning how to assess whether museum objects might fade when exposed to light using “microfadeometry”. Microfadeometry is a technique that involves exposing a very small area on an object to an intense light for a short amount of time and recording the colour change on this small area. By comparing the colour change with references, it is possible estimate whether the object is sensitive to light or not.

Michela Rampa BM image1
Examination of a 16th century Indian painting

Why is it so important to assess the lightfastness of museum objects? Many museum objects are light sensitive, for instance: watercolours, prints or textiles. We cannot stop fading from occurring when these objects are displayed, but we can ensure that light-sensitive objects fade so slowly that they will be seen by countless generations of visitors to the Museum in the future. Knowing if an object is likely to fade when exposed to light helps curators to decide how long  it can be displayed and under which conditions. For example, microfading tests carried out on Hokusai’s iconic prints ‘The Great Wave’ and ‘Red Fuji’ last year showed that these should be displayed using dim light for a short amount of time (read about it here).

Michela Rampa BM image 2
Experimental Technical Imaging laboratory in The British Museum

I am currently investigating the lightfastness of some Indian paintings, which will go on display in the new Albukhary Foundation Galleries of the Islamic World at the end of this year. One of them is a very colourful Hamzanama painting made in 1500. (Hamzanama is a series of manuscripts, most of them illustrated, that narrate the legendary deeds of Amir Hamza, the uncle of prophet Muhammad). It is very valuable and I have identified at least 13 different colours on it! I expected that most colours on this painting were produced using mineral pigments and therefore would not fade. However, I am discovering that, on the contrary, several colours, such as green, are light sensitive! I am hoping to perform more analysis to find out why these colours are affected by light. Work in progress!

In the meantime, if you want to know more about the work scientists do at the British Museum, please come and find me and the rest of the Scientific Research team at our annual event ZOOM IN: a closer look at science on Saturday 17 March 2018, 10.00 – 16.00, in the Great Court at The British Museum. Learn about all of the different techniques that are used to analyse the Museum’s collections, handle different kinds of raw materials and see the latest behind-the-scenes technology in action. This is a FREE event too!

Michela can be contacted by email and on LinkedIn. You can find out more about the upcoming Albukhary Foundation Galleries of the Islamic World on The British Museum website.

Five minutes with… Simon Crutchley, Remote Sensing Development Manager at Historic England

Today in our British Science Week 2018 series, we sit down and talk to Simon Crutchley, Remote Sensing Development Manager at Historic England. Remote sensing is the science of obtaining information about an area from a distance, from aircraft or satellites scanning the earth. Read on to find out about his career and the most exciting things he’s been up to…

What’s your scientific/heritage background?

After studying classics at university and spending a few years digging on “the circuit”, as it was called, I got a job with what was then the Royal Commission on the Historical Monuments of England (RCHME) as an Air Photo Interpreter. Since that date I’ve worked in the remote sensing field for nearly 30 years, initially using standard aerial photographs, but over time working with lidar (airborne laser scanning) and more recently satellite imagery.

What’s your role at Historic England?

My primary role at Historic England (HE) is to look at new and cutting edge scientific techniques being used in remote sensing in areas outside heritage, and develop ways to utilise and integrate them into existing workflows. This is both for Historic England and the wider sector.

What’s been the most exciting / challenging thing you’ve worked on recently?

It’s probably a toss-up between two pieces; one is the work I’ve done to try and expand use of the lidar data, released by the Environment Agency (EA) in 2015, by the wider heritage sector, and particularly amateur archaeologists. For this I’ve put together some very basic instructions on the HE website to explain how to access the EA data and then process it so as to produce visualisations to help with recording and interpretation.

Fig_1_Comparative _lidar_visualisations
Comparison between the standard jpg tile provided by the Environment Agency through Flickr (left) and a more advanced visualisation technique, based on the raw data, in this case a Simple Local Relief Model (SLRM) (right). The SLRM is the result of a procedure that separates local small-scale features from larger landscape forms, thereby enhancing features of potential archaeological interest. Tile SU1257 – LIDAR data © Geomatics Group 2008.

The other is the work I’ve done to provide access to the data from the Cannock “Chase Through Time” project, which explored the rich history of Cannock Chase area of Outstanding Natural Beauty. There has been a strong volunteer aspect to the project and one of my key roles has been to create an online map, where it’s possible for users to view the results of the mapping carried out by HE against a surface model derived from the lidar data acquired for the project. Volunteers then have the possibility to download the original lidar data to carry out further analysis themselves and also to take ground photos of features of interest and add them to the map.

Fig_2_Cannock_StoryMap
A screenshot of the StoryMap web app for the “Chase Through Time” project for Cannock Chase, Staffordshire. All across the Chase, previous generations left their mark on the land – including one of the best-preserved First World War landscapes in England.

Who inspires you?

It may sound a bit corny, but people who try to make a difference; people like Bill Gates who devotes part of his admittedly massive fortune to addressing challenges not being tackled by other agencies, such as his malaria initiative.

What do you love most about your job?

The variety. One day I might be providing advice to a member of the public who thinks they may have seen something interesting on Google Earth or wants to know more about lidar; the next I’ll be working with raw lidar data, processing it to bring out subtle features of a landscape no-one has recognised before; the next I’ll be collaborating with other project members working out how to get the data from a project into GIS and shared with others.

In a single sentence, tell us what’s great about heritage science?

Heritage Science provides the data that enables us to understand what the world looked like in the past and how our ancestors interacted with it.

Fig_3_Savernake_DSM_DTM
Comparison of the Digital Surface Model (DSM) and Digital Terrain Model (DTM) derived from lidar data for part of Savernake Forest, Wiltshire. The DSM is based on the first return from the lidar pulse and represents the top of the canopy; the DTM is based on filtered data, designed to remove all “above ground” points such as vegetation. This view reveals the presence of an Iron Age enclosure together with several other features. Lidar © Forestry Commission; source: Cambridge University ULM (May 2006).

It’s British Science Week!

It’s that time of the year again! To celebrate British Science Week 2018 (9-18 March), we’ll once more be running a series of blog posts from heritage scientists across NHSF member organisations.

Over the next 10 days, activities and public events around the theme of Science & Technology will be running throughout the country, many of them free – you can find a full list here.

We have an exciting series of posts planned, to make sure that Heritage Science is represented in the festival. What is heritage science? The application of science and technology to cultural heritage, to improve our understanding and enjoyment of it. Keep an eye on this blog to find out about colours and light in Indian paintings, laser scanning the Earth, and plenty more – follow us on Facebook or Twitter to get notified of new posts.

 

Weston cons studio - new book binding
New book binding at Weston conservation studio. © National Trust