National Gallery Technical Bulletin (free archive)
by National Gallery Scientific and Conservation Departments · The National Gallery, London
The National Gallery London's journal of scientific examination of paintings, published since 1977. The archive offers free PDFs analysing grounds, pigments, layer structure and working methods of painters such as Titian, Rembrandt and Van Eyck. It shows through cross-sections and pigment analysis how the old masters actually built their paintings.
More resources on Oil Painting
Traditional Oil Painting: Advanced Techniques and Concepts from the Renaissance to the Present
Virgil Elliott's account of indirect oil painting methods, from the Flemish and Venetian traditions to modern practice. It covers grounds, imprimatura, underpainting, glazing and scumbling, fat-over-lean layering, mediums, pigment properties and archival permanence.
Alla Prima II: Everything I Know About Painting – And More
Richard Schmid's treatise on direct, wet-into-wet oil painting. It covers palette setup, colour mixing and colour charts, values, edges, and painting from life across still life, landscape and portrait, with many demonstrations.
Studio Safety Guide: Create Without Compromise
Gamblin's practical guide to a safe oil painting studio. It covers solvent choice and aromatic content, ventilation rates, pigment toxicity (cadmium, cobalt, lead white), solvent-free painting, and preventing spontaneous combustion of oily rags. The manufacturer mentions its own products (Gamsol), but the guidance applies to any brand.
The Science and Practice of Oil Painting
Harold Speed's 1920s manual on oil painting practice, covering tone, colour, brushwork, mediums and grounds, with analyses of old-master methods. The full 1926 Chapman and Hall edition is free to read and download at the Internet Archive.