Caspar David Friedrich

A sourced technical report. Every claim cites a source key; the sources are listed at the end. "Uncertain" marks claims that are unverified, disputed or taken from a single object.

Summary

Friedrich painted in oil on fine, plain-weave linen that he bought already primed. The grounds had two to four thin layers: a warm lower layer (red or ocher) under a light, lead-white-rich top layer [KÖR p.284; CATS p.127]. Over a precise graphite or ink underdrawing he laid a very thin underpainting, then one or two very thin paint layers [SMB-proj; CATS p.127]. He used few pigments. Before about 1820 his main blue was smalt, a semi-transparent cobalt glass; after that, cobalt blue, with chrome yellow among the yellows [ALF pp.341, 348–349]. Gradations come from stippling and from thin paint pooling in the fine texture of the ground, not from thick blending [CATS p.127; NG p.56].

Terms. Ground/priming: the preparatory layers between canvas and paint. Cross-section: a microscopic sample cut through all layers. IRR (infrared reflectography): imaging that shows carbon-based drawing under paint. XRF (X-ray fluorescence): elemental analysis. Glaze: a transparent paint layer. Impasto: thick, raised paint. Craquelure: the network of cracks in paint or varnish.

1. Supports

• Fabric. Fine linen canvas; two large canvases of 1808–10 were cut from adjoining sections of one roll, established by weave matching [CATS p.127 and n.2]. The Dresden paintings use locally grown flax, handwoven in plain weave. In his late work he preferred "finer, more densely woven canvases" [KÖR p.283].
• One piece of cloth. A single strip of canvas whatever the size, so even large formats have no seams [KÖR p.283].
• Thread count. Canvases bought ready-primed in Dresden in 1827–34 by another painter measure 10–16 threads/cm in both directions [CATS-E pp.45–47].
• Sizes. From about 32.5 × 45 cm [RSC p.42] to 110.6 × 171.4 cm [CATS p.126].
• Stretching. Mostly softwood stretchers with blind mortise-and-tenon corners and hardwood wedges [KÖR p.283]. Uneven pull marks (cusping) on one edge only of a small canvas suggest it was cut from a larger, already-primed length [NG pp.51, 55].

2. Grounds

• Commercial, multi-layer, warm underneath. Commercially primed canvas cut from long lengths; Dresden suppliers sold primed cloth in several colors [KÖR p.284]. Two to four thin layers [KÖR p.284]. Lower layers hold inexpensive ocher, burnt red earth, chalk and barium sulfate and "only served to smooth and even out the weave texture." Upper layers are mostly lead white, probably in oil; he painted mostly on "a patchy whitish ground" [KÖR p.284].
• One pair of canvases (1808–10). Three priming layers: bright red, then two light brown. The first two were applied with a spatula; the third looks roller-applied and has "a finely textured structure" [CATS p.127; SMB-blog]. In a cross-section the red layer holds aluminosilicate and iron oxides, followed by several yellow-gray lead-white layers with iron oxides, vermilion grains and calcium-rich grains [NPJ25].
• A small canvas of about 1811. Two layers, both chalk and lead white with a little umber and ocher; the upper has more lead white, so it is lighter and cooler. The binder is walnut oil [NG p.55].
• Tool marks. X-rays show wavy strokes from priming knives in the lower layers. The top layer was brushed, and its bristle striations "shine through the thin upper paint layers" [KÖR p.284].
• Colored grounds. Some paintings have a reddish-ocher or pink top ground that stays visible under loose paint or is left bare in places [KÖR p.284; HH].
• Weave. The lower layers level the weave [KÖR p.284]; the visible micro-texture comes mainly from the top ground (brush striations or roller texture).

3. Underdrawing

• Media. Graphite pencils of different hardness and black chalk, sometimes in two passes: a faint first outline, then a bolder one. Straight lines were probably ruled [CATS pp.128, 131]. Chalk and pencil first, then "quill-pen and ink," is also reported [CATS p.132; NG p.49]; faint ruled lines (possibly pencil) under thicker ink lines [NG pp.49, 58].
• Over his career. Early works are drawn almost entirely in graphite, and the drawing often stays visible through the very thin paint. From 1811 to the mid- or late 1820s a pen is added and the paint gets denser. Late works use a pointed brush, and the drawing is almost fully covered [ART, summarizing Mösl 2021].
• Precision. "Rich in detail," with "no gradation of detail according to significance" [CATS p.132]. Drawn elements were sometimes left unpainted [CATS p.128].
• Through the paint. Lines "still partly shimmer through" [CATS p.132]; traces of drawing show as dark dots at color boundaries [HH].
• Tools. A picture of his studio of 1811 shows two palettes, a set square, a T-square, a ruler and a maulstick [KÖR/Busch pp.326–327].

4. Pigments

Pigment	Evidence	Notes
Lead white	[CATS p.127]; [NG pp.51, 56]	The main white; in the grounds too
Smalt (cobalt potash glass)	[CATS p.127]; [NG p.56]; [ALF]	Several grades from pale gray to deep blue, alone or with lead white [NG p.56]. About 3 wt% Co [NPJ25]. Chosen "on account of its semi-transparent property" [CATS p.127]
Ochers and earths (goethite, hematite)	[ALF p.348]; [CATS p.127]	Yellow and red earths
Vermilion/cinnabar	[NPJ25]; [KÖR fig. 6]	Small admixtures
Red iron oxide	[NG p.56]	A few particles
Bone black	[NG p.56]	In a mixture with smalt, Naples yellow, ochre and possibly Prussian blue
Prussian blue	"Possibly" [NG p.56]; inferred from K and Fe [ALF Table 2]
Cobalt blue	From 1818/24 [ALF]; "almost entirely replaced smalt… after about 1820" [NG p.56]
Chrome yellow (lead chromate)	1817 and 1818/24 [ALF]
Green pigments	"a few… green" pigments [CATS p.127]; copper greens and green earth [MÄD p.102]	See §8

5. Binding media

• Walnut oil in ground and paint of one small canvas [NG p.55], the only published medium analysis found. Linseed or poppy oil, resins and driers are unverified.
• Egg white as a temporary coating over fresh paintings [CATS p.127; KÖR p.283].

6. Layers and application

• Number of layers. "One to two very thin layers" of paint [SMB-proj]. One canvas: primings 1–3, underdrawing, underpainting, one smalt paint layer, egg white, then later varnishes [CATS fig. 3]. Another: a first dark-blue layer, then light blue, pink and white in places [CATS p.127]. A third: "a single thin layer using remarkably few pigments" [NG p.56]. A fourth (1807/08): two ocher ground layers, a patchy white ground, a thin violet layer (smalt splinters and cinnabar), then a very thin pale-yellow layer [KÖR fig. 6].
• Film thickness. "Very, very fine layers" [SPK]; a "gossamer-thin film" [CATS p.127].
• Pooling. The thin paint "accumulated in the depths of the textured ground layers," producing the finest dots of color and "almost continuous gradations" without visible brushstrokes [CATS p.127].
• Stippling. Some passages are stippled, which "enhance[s] the transparency and light scattering" [NG p.56; KÖR fig. 7].
• Strokes. Early brushwork is "painstaking… small strokes of paint placed side by side like a closely woven textile" [NG pp.49–50]. Paint was modeled while still wet [MOST-abs].
• Impasto. Limited in early works [NG p.50]; some later works mix thick and thin paint and leave the ground bare in places [HH].
• Order of work. Ground (bought), then underdrawing, then a "very thin underpainting," then paint [CATS p.127]; small details were added last, over finished passages [NG p.56; CATS p.130]. Brush types (sable or bristle) are undocumented in these sources.

7. Condition and aging

• Fragility. The thin paint made the paintings "exceptionally prone to damage" [SMB-proj]; many micro-losses come from abrasion in past cleaning [SMB-blog].
• Smalt discoloration. Smalt has partly lost its color in one painting: low potassium (4.9 wt%) and changed cobalt coordination show an intermediate stage of degradation; a simulation of the original colors comes out cooler and bluer [NPJ25; SMB-blog]. Smalt can turn brown over time [HH].
• Craquelure. One painting has an elongated craquelure, probably from pressure on the back [HH].
• Pentimenti. Few [NG p.49; ART; CATS p.129].

8. Greens

• Mostly mixed. The Dresden team (14 paintings) writes that "the palette was very sparing" but the greens show a "lush variety" ("üppige Vielfalt"). The true greens were "copper-containing pigments and green earth." Greens were often mixed from blue and yellow: Prussian blue "very often," smalt and cobalt blue as well, with yellow ocher, Naples yellow or chrome yellow [MÄD p.102]. Green passages often have "several (up to four) layers of different greens" [MÄD p.102].
• One painting of 1808. XRF found Cu and As in the same layer, with no intact copper arsenite: the authors assume a degraded Scheele's or Schweinfurt green [MÄD p.102]. Single object. Since 1808 predates Schweinfurt green (1814), this would be Scheele's green unless the layer is later (inferred).
• Rinmann's green, rare, found on three paintings of about 1819–23 [MÄD p.102 n.3; MOST-abs].
• A dating test. A painting was de-attributed partly because its greens are cobalt blue mixed with chrome yellow, anachronistic for its supposed date of 1798/99 [MÄD p.102].

Green	Date and availability	Source
Green earth (terre verte)	Ancient; in painters' manuals through the 19th century	[AP1 pp.143–144, 147]
Verdigris / copper resinate	Old; "rarely found in eighteenth- and nineteenth-century paintings"; around 1816 still made as green "varnishes"	[AP2 pp.132, 149]
Scheele's green (copper arsenite)	"Introduced in 1778"; "use as an artist's pigment is little documented"	[AP3 p.221]
Schweinfurt/emerald green	Made from 1814; a trade secret until 1822; sold in tubes from 1832; earliest easel finds c.1832	[AP3 pp.222–223, 259; WEB-em]
Rinmann's green (cobalt-zinc oxide)	1780; "poor tinting strength and high cost… kept it in limited use"	[WEB-co]
Chromium oxide (opaque)	"Rarely used because of its high price" (1831); earliest finds 1845–50	[AP3 p.275]
Viridian	Made c.1838, patented 1859, earliest finds 1863	[AP3 pp.274–275; CL-vir]
Chrome green (chrome yellow + Prussian blue)	Appeared shortly after chrome yellow; chrome yellow made commercially in Germany only from 1820	[AP1 p.189; AP3 pp.203–204; MÄD p.102]

Green earth is translucent, weak and short of body [AP1 p.146; FIELD p.129].

9. The tubes here

The historical names in this note correspond to these tubes: ochers and yellow earths → yellow ochre; red earths and red iron oxide → red earth; cinnabar → vermilion; the green pigments → green earth, copper green and Rinmann's green.

10. At this easel

• Support. Plain-weave linen with ground layers laid from the tubes.
• Paint. Pigment from the tubes with an oil-medium share.
• Taking paint off. A brush picks up wet paint as it passes; that is how paint comes off the canvas.
• Everything else the easel does is in the easel guide.

Sources

• [CATS] Mösl, K. and Schneider, F., CATS Proceedings III, pp.124–133. https://pure.kb.dk/ws/portalfiles/portal/10104814/CATS_proceedings_III.pdf
• [CATS-E] Filtenborg, T. and Krarup Andersen, C., same volume, pp.43–54 (same URL).
• [RSC] Royal Society of Chemistry, The Chemistry of Art, case study 9. https://edu.rsc.org/download?ac=14318
• [SMB-blog] Mösl and Schneider, "In neuem Glanz," 2016. https://blog.smb.museum/caspar-david-friedrich-alte-nationalgalerie/
• [SMB-proj] Alte Nationalgalerie, conservation project page. https://www.smb.museum/en/museums-institutions/alte-nationalgalerie/collection-research/conservation-care/caspar-david-friedrich-project/
• [SPK] Interview with Ina Reiche, 2016. https://www.preussischer-kulturbesitz.de/en/news-detail-page/article/2016/01/22/getting-to-the-bottom-of-art-works-by-caspar-david-friedrich-layer-by-layer.html
• [NG] Leighton, Reeve and Burnstock, National Gallery Technical Bulletin 13 (1989), pp.44–60. https://www.nationalgallery.org.uk/media/15749/leighton_reeve_burnstock1989.pdf
• [ALF] Alfeld, Mösl and Reiche, X-Ray Spectrometry 50 (2021), pp.341–350. https://pure.tudelft.nl/ws/portalfiles/portal/94318269/xrs.3195.pdf
• [NPJ25] de Mecquenem et al., npj Heritage Science (2025). https://www.nature.com/articles/s40494-025-01953-y
• [KÖR] Körber, M., "Head and Heart and Hand," in Caspar David Friedrich: Where It All Started, SKD Dresden 2024, pp.281–285 (Busch, pp.326–327); publisher excerpt: https://media2.hugendubel.de/shop/coverscans/495PDF/49546505_1ccd3397eb4244e1a938b4291c8c6b00.pdf
• [SKD] SKD research project page. https://forschung.skd.museum/projekte/detail/forschungen-zur-maltechnik-caspar-david-friedrichs/
• [ART] Slenczka, review of Mösl 2021, ArtHist.net 2025. https://arthist.net/reviews/43869
• [HH] Hamburger Kunsthalle, GigaPixel commentary. https://cdfriedrich.de/gigapixel/
• [MÄD] Mäder, Körber, Hohenstein, Fuhrmann, Stege, Wagner and Birkholz, METALLA Sonderheft 13 (2025), pp.101–103. https://metalla.org/index.php/METALLA/en/issue/download/393/75 (DOI 10.46586/metalla.v.2025.i13)
• [MOST-abs] Most et al. 2024, abstract (DataCite). https://api.datacite.org/dois/10.25360/01-2024-00012
• [AP1] Feller (ed.), Artists' Pigments vol. 1 (1986). https://www.nga.gov/sites/default/files/migrate_images/content/dam/ngaweb/research/publications/pdfs/artists-pigments-vol1.pdf
• [AP2] Roy (ed.), vol. 2 (1993). https://www.nga.gov/sites/default/files/migrate_images/content/dam/ngaweb/research/publications/pdfs/artists-pigments-vol2.pdf
• [AP3] FitzHugh (ed.), vol. 3 (1997). https://www.nga.gov/sites/default/files/migrate_images/content/dam/ngaweb/research/publications/pdfs/artists-pigments-vol3.pdf
• [FIELD] Field, Chromatography (1835), p.129. https://archive.org/details/chromatographyor00fieluoft
• [WEB-em] https://www.webexhibits.org/pigments/indiv/history/emerald.html ; [WEB-co] https://www.webexhibits.org/pigments/indiv/overview/cogreen.html
• [CL-vir] ColourLex, Viridian. https://colourlex.com/project/viridian/