National Gallery Technical Bulletin Volume 12, 1988

Analyses of Paint Media

John Mills and Raymond White

Notes to the Table

1. The blue paint possessed a very porous structure and traces of pine resin found in this sample are likely to represent traces of varnish which have been trapped. No resin was detected in any of the other samples. Blue overpaint was identified as based on egg and oil.
2. The difference in P/S ratios gives one confidence in the use of different oils in the various areas of this work sampled. The green paint in sample 4, from the left-hand side of the painting, was markedly glaze-like in comparison to the green paint sampled from the right. Badly flaking red-brown overpaint was found to be in glue distemper.
3. Once again a clear difference in P/S ratios suggests selective use of walnut oil in the lighter paint and linseed in the darker areas. Small amounts of pine resin were identified in the blue and grey paints. Though not major, they seem too large to be attributed to traces of residual varnish.
4. A double ground was present in this picture, which exhibited some signs of poor adhesion between the upper and lower ground. The latter, red ground examined in sample 1, gave an indication of sensitivity to water. There would appear to be some form of glue and linseed oil emulsion involved as the binder.
5. In this instance it was possible to examine two types of white from No.6508a, each differing markedly in 'warmth'. Sample 3 was very warm and is based on linseed oil — no resin was detected. Sample 1 was decidedly cooler and had a much higher P/S ratio, suggesting walnut oil. The low value for the ratio of the C9 to C8 dicarboxylate (1.6) points to the probability that this walnut oil had been prepolymerized, that is heat-bodied (note 1,2).
6. Walnut oil was identified in both samples of white (cool) paint from this panel. In addition, results for sample 6 suggest that the walnut oil had been heat-bodied (C9/C8 dicarboxylate ratio = 3.0). Traces of hopane homologues in sample 8 lead one to conclude that some asphaltum or bitumen has been included in this sample (note 3) (see also p. 18 and p.31). Samples of later red paint from red scrolls on the reverse of each panel contained egg tempera.
These van Heemskerck panels are discussed in detail on pp.16–35.
7. Glue distemper was found in all samples investigated from this panel. The sensitivity of such a medium to damp probably accounts for the losses and staining observed on the reverse.
8. No trace of resin could be detected in any of the samples. A dark varnish removed on swabs during cleaning was also examined. It was found to contain dammar resin and substantial amounts of resin labdanes from a Leguminosae source. In fact the chromatogram suggested the use of copaiba balsam. At one time such a material was popular as an additive to solvents used by restorers during cleaning. The short-term effect was to reduce the matt appearance of the paint surface remaining after the removal of the top varnish (note 4,5). No pine resin was detected in this varnish.

References

1. Mills, J.S. and White, R., 'Organic Mass-Spectrometry of Art Materials: Work in Progress', ‘National Gallery Technical Bulletin’, 6 (1982), pp.3–18.
2. Mills, J. S. and White, R., 'Analyses of Paint Media', ‘National Gallery Technical Bulletin’, 7 (1983), p.67.
3. White, R., 'Organic Blacks and Browns', ‘National Gallery Technical Bulletin’, 10 (1986), pp.58–71.
4. Mills, J.S. and White, R., ‘The Organic Chemistry of Museum Objects’, Butterworths (London 1987), p.92.
5. Schiessl, U., '"Apage Satanas! Apage Copaiva!" ϋber Materialmoden in der Restauriergeschichte', ‘Zeit-schriftfur Kunsttechnologie und Konservierung’, 1, 1 (1987), pp. 165–75.

Artist	Picture	Date	Sample	Medium	P/S	Oil type	Note	
Botticelli,
Follower of	Virgin and Child with an Angel
No.589	3rd quarter 15th C.(?)	1. Blue sleeve, Virgin's robe
2. Red Glaze, Virgin's red dress
3. White highlight, arch, R.H. side	Egg

Egg

Egg			1	
Veronese	Saint Mary Magdalene laying aside her Jewels
No.931	2nd quarter 16th C.	1. Opaque green of cloak of R.H. figure, mid R.H. edge
2. White coat (highlight) of figure with red cap
3. Red-brown, over green
4. Green glaze L.H. figure's dress
5. Transparent brown layer over green, R.H. figure
6. Grey fluted column, upper R.H. corner	Oil

Oil

Oil
Oil + resin

Oil

Oil	1.2

3.2

3.4 3.5

3.7

1.9	Linseed

Walnut

Walnut
Walnut

Walnut

Linseed	2	
van der Heyden	An Architectural Fantasy
No.992	1660s	1. White cloud
2. Dark grey cloud
3. Blue sky	Oil
Oil + resin
Oil + resin	3.7
1.7
1.8	Walnut
Linseed
Linseed	3	
Treck	Still Life with a Pewter Flagon
No.4562	1649	1. Red, lower ground
2. Brownish black shadow
3. White napkin	Oil + glue
Oil
Oil	1.9
1.7
1.9	Linseed
Linseed
Linseed	4	
van Heemskerck van Heemskerck	The Virgin and S.John the Evangelist
No.6508a
The Donor and S. Mary Magdalene
No.6508b	Mid-16th C. Mid-16th C	1. White headdress (obverse)
2. Green of S. John's cloak (obverse)
3. Warm white robe (reverse)
4. Black of niche (reverse)
5. Green glaze band of S. Mary's robe (obverse)
6. White of donor's surplice
7. White sleeve of bishop's cloak (reverse)
8. Black paint of niche (reverse'	Oil
(prepolymerized)
Oil + resin

Oil

Oil
Oil

Oil
(prepolymerized) Oil

Oil + bitumen	3.8

1.5

1.4

1.4
1.8

3.4

3.5

1.4	Walnut

Linseed

Linseed

Linseed
Linseed

Walnut

Walnut

Linseed	5 6	
French School(?)	Richard II presented to the Virgin and Child by his Patron Saints (The Wilton Diptych)
No.4451	c.1395 or later	1. Red of helmet from lacuna (reverse)
2. Blue of shield (reverse)
3. Ground, corner of frame (reverse)	Glue

Glue
Glue			7	
Caspar David Friedrich	Winter Landscape with a Church
No.6517	c.1811	1. White snow
2. Grey sky
3. Ground, L.H. turnover	Oil
Oil
Oil	2.4
2.5
2.5	Walnut
Walnut
Walnut	8	

National Gallery Publications Published by order of the Trustees

Scientific Adviser, John Mills
Chief Restorer, Martin Wyld
Editor: Ashok Roy

© The National Gallery 1988

All rights reserved. No part of this publication may be transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without the prior permission in writing from the publisher.

British Library Cataloguing in Publication Data

National Gallery

National Gallery, technical bulletin.—Volume 12, 1988.
1. Painting — Conservation and restoration—Periodicals
I. Title
751.6'05 ND1640

ISSN 0140–7430
ISBN 0 947645 63 2

Designed by James Shurmer

Printed and bound in Great Britain by William Clowes Limited, Beccles and London