Introduction

Among these, 15 big size canvases in the Munch’s collection, were used as preparatory drawings for the Aula Magna canvases of the Oslo University and nowadays they present extensive salt efflorescence’s, roughly identified as sulfates. The removal of these salts is requested in order to create optimal conservation conditions in view of the relocation of the entire collection of the museum in a new building in 2020.

This poses several key questions to understand the artistic techniques of Munch and for the preservation of its works: WHAT are Munch’s painting/drawing techniques? WHY are these salts appearing? HOW can we predict and mitigate their effects?

The formation of these efflorescence crystals is mainly due to exposure to outdoor extreme conditions (different sketches were mounted outdoors, but Munch said that some paintings stayed outdoors for 4 years, exposed to rain, low temperature during winter, snow, sun radiation etc.) and possible pretreatment of the canvases with elemental sulfur.

All the 15 sketches are executed on thin cotton canvases with no applied ground and 5 of these are lined with a glue paste method with added synthetic PVA. 13 of the sketches were mainly executed with wax crayon (lanolin and vegetable oil) directly on to the canvases, but there are large areas of exposed canvas.

The research project THE SCREAM is focused on the scientific and technical study of Edvard Munch canvases present in the Munch Museum in Oslo (Norway) and their crystallization phenomena together with the characterization of crayons and pastels from the collection of the museum.

The innovative approach proposed by The SCREAM project, which is built up on the collaboration between 3 recognized institutions in the area of cultural heritage – the HERCULES Laboratory from Evora University, the Munch Museum and the Getty Conservation Institute in Los Angeles - shows an inter- and transdisciplinary character, competences and infrastructures of high level for conservation science and conservation-restoration of movable heritage being thus represented.

During this 3 year project, 6 tasks will be developed and will advance the state of the art on crystallization and de/recrystallization processes of salts (such as Zn and Mg sulfates and metal carboxylates) present in modern and contemporary heritage, with particular attention paid to canvases belonging to the collection of Munch Museum. Furthermore, new solutions and tools for the treatment of the canvases as well as scientific modelling of the formation processes of these salts and neo-formation products in different climatic and storage conditions, will be a basis for future studies on the physical-chemical processes of crystallization, meant to predict their behavior and their impact on the artwork on canvas sensitive to fluctuation of the environmental parameters and water uptake. This will allow the creation of a plan for mitigating the effect of these salts and prevent their re-crystallization after conservation-restoration treatments.

The proposal will mark a step forward in the research on crystallization and re-crystallization of salts on painted canvases belonging to the Modern period and will also advance the conservation field with new tools and solutions for practical treatments. The case study based on some of Munch’s works can be seen as pilot for other studies on the behavior of multi-layered structures sensitive to moisture uptake and fluctuations of environmental parameters. The knowledge to be produced from modeling and artificial ageing would help in predicting the behavior of these structures and also in creating a plan for mitigating the effects of the salt when present or preventing their occurrence after treatments.