VNIR- and SWIR-HSI database of unvarnshied oil paints on canvas

Context

Hyperspectral libraries for unvarnished oil paints on canvas. The oil colours and mixtures selected as swatches were based on materials that Edvard Munch (1863-1944) is suspected to have used on his Aula paintings (1909-1916) situated at the University of Oslo's festive hall in Norway's capital.

Contents

A total of seven files are included, which may be classified as:

PDF file: description of paint composition, library layout and acquisition conditions for HSI. All spectra included as images.

HSI files: .img and .hdr files (contained in three .zip files) are provided for two separate libraries ((1) and (2)). Spectra (in the VNIR and SWIR ranges) for the endmembers are presented in a .xlsx file per library.

ATR-FTIR files: .sg files (contained in one .zip file) for the FTIR spectra for oil paints found in Library (2) - these serve as ground truth (in the MIR range) for the oil paints.

Library 1 (VNIR only)

The first set of reference canvases (Library (1)) was made in 2009 at the Conservation Studies department (UiO). Pigments in powder form were ground in linseed oil and applied by brush, with increasing amounts of white spirits. This library served as a reference for unvarnished, handmade oil paints in linseed oil, and was scanned after 11 years of natural ageing. Captured in four swathes in the VNIR range (400-1000 nm) - each canvas is comprised of two swathes (001 and 002; 003 and 004).

Files:

Library (1) VNIR.zip

001*

Library1_001_[...]_raw_rad.hdr

Library1_001_[...]_raw_rad.img

White ref.txt

002

003

004

Spectralon references (from manufacturer)

VNIR Spectralon Ref.tif

(*) sub-structure for "002-004" mirrors that for "001"

Library 2 (VNIR & SWIR)

The second set of reference canvases (Library (2)) was made in 2021 using prefabricated tube paints containing pigments in linseed oil, as produced in the Classic Oil Colour series by Old Holland (Netherlands). The paint applications by brush were made both neat and diluted in white spirits (0–10% w/v), and selected swatches per colour/mixture were varnished (both single and double applications) with gum dammar and Laropal A81 (10% w/v in Shellsol A and B, with Tinuvin 251 UV stabiliser). Captured in six swathes in the VNIR range (400-1000 nm) and six swathes in the SWIR range (1000-2500 nm) - each canvas is comprised of three swathes (001-003; 004-006).

Files:

Library (2) VNIR.zip

001*

Library2_001_[...]_raw_rad.hdr

Library2_001_[...]_raw_rad.img

White ref VNIR.txt

002

003

004

005

006

Spectralon references (from manufacturer)

VNIR Spectralon Ref.tif

Library (2) SWIIR.zip

001*

Library2_001_[...]_raw_rad.hdr

Library2_001_[...]_raw_rad.img

White ref SWIR.txt

002

003

004

005

006

Spectralon references (from manufacturer)

SWIR Spectralon Ref.tif

(*) sub-structure for "002-006" mirrors that for "001"

Old Holland Oil Paint FTIR Library.zip

Credits

Jan Dariusz Cutajar (conservator, PhD fellow): conceptualisation;  methodology - making of library (2); data collection: HSI acquisitions for library (1), FTIR acquisitions for library (2); data curation; data visualisation; validation

Mirjam Liu & Karen Mengshoel (conservators): methodology - making of library (1)

Hilda Deborah (imaging scientist): data collection: HSI acquisitions for library (2)

Tine Frøysaker (conservator): supervision; resources; funding

The NTNU Colourlab (Gjøvik, Norway) (as part of the CHANGE-ITN consortium) is acknowledged for generous access to the HSI cameras used in compiling these libraries.