General · EdgepediaSeptember 17, 20268 min read

Putty

Putty is a dough-like cement, traditionally made by mixing finely powdered chalk (whiting) with linseed oil, used to bed and seal glass panes in window frames, to fill holes and inequalities in woodwork, and, in specialized forms, to seal plumbing fixtures. The oil oxidizes over time and gradually hardens the paste into a dense, adherent mass.¹ A chemical dictionary cited in a glazing-patent specification defines the traditional product as from 12 to 18 percent by weight linseed oil with the balance being chalk.²

Key fact	Detail
Traditional composition	Finely powdered chalk (whiting) intimately mixed with raw or boiled linseed oil to a tough dough; one patent-era definition gives 12–18% linseed oil by weight, balance chalk¹^•²
Hardening mechanism	Oxidation of the linseed oil, over weeks to months; boiled oil, litharge, and other driers were used when faster drying was required¹^•³
Principal uses	Bedding and face-glazing glass in wood and metal frames; filling nail holes in woodwork; setting plumbing fixtures¹^•⁴
Working times	Skins in 2–4 days; painted at 7–21 days, final coat within 28 days; a kilogram covers 3–5 meters of fronting³
Main limitation	Hardens and cracks with age and needs periodic replacement; linseed oil destroys the edge seal of insulated and laminated glass units⁵^•³
Etymology	Mid 17th century, from French potée, literally "potful"; the word originally denoted finely divided tin oxide used for polishing, now called putty powder⁶^•¹

Composition and hardening

The classical recipe is simple: whiting, a purified powdered chalk, worked into raw or boiled linseed oil until the mixture reaches the consistency of tough dough.¹ Historical literature also records harder stopping putties and formulations containing white lead, driers, pigments, other oils, or varnish.⁷ A 2002 patent specification gives representative modern commercial mixtures: a white linseed oil putty of approximately 10.1 wt. % linseed oil, 32.0 wt. % fine calcium carbonate, 56.9 wt. % coarse calcium carbonate, and 1.0 wt. % talc, and an elastic glazing compound of 7.5 wt. % marine oil, 4.0 wt. % vegetable oil, 42.5 wt. % fine and 44.5 wt. % coarse calcium carbonate, and 1.5 wt. % talc.⁸ The balance between fine and coarse particles matters practically: fine grinding promotes length, stability, and oil retention, while coarse particles improve handling and knifing characteristics.⁸

Curing is oxidative, not evaporative. The oil polymerizes on contact with air, and the putty hardens into a dense adherent mass over weeks to months.¹^•³ When faster setting was wanted, boiled oil and sometimes litharge (lead monoxide) and other driers were added; lead compounds catalyze the drying of linseed and other drying oils, producing products that are hard yet flexible and tough.¹^•⁹ A 1924 patent by Julius Laurila described mixing in fine washed white sand heated to about 200 degrees, at 20 to 30 percent by volume of the mixture, claiming a putty far more durable in exposed places because it would not crack and break off.¹⁰ Accelerating the cure has a cost: metallic driers speed the surface at the expense of long-term flexibility, so the fillet goes brittle sooner.³

Window glazing

Glazing is the principal use. Putty is pressed into the rebate (the glazing channel) of the frame as a bed for the glass, the pane is secured with glazing points, and the exterior joint is finished as a beveled front or face putty with a knife.¹¹^•¹² The material serves three functions at once: it secures the pane within the frame, allows for expansion and contraction from temperature changes, and seals the gap against the passage of air, water, and particulates.⁸ On a well-glazed window the glass sits in a bed of putty and the exterior fillet is packed tight and bonded to both wood and glass.¹²

Preparation and painting govern the result. Glazing compound should only be used on wood brushed with linseed oil and primed with an oil-based primer, so the wood does not draw oil out of the putty and weaken the bond; after the glass is set, the final putty is applied and beveled, and the exterior paint should cover the putty and lap slightly onto the glass to complete a weathertight seal.¹³ Painting is required, primarily for UV protection and water resistance, and new putty must cure before painting or it will shrink.¹⁴^•¹⁵ Timelines vary with temperature, humidity, air movement, sunlight, and fill volume: the NPS guidance describes painting once a skin forms, usually in 2 or 3 days, while a commercial oil-and-solvent glazing compound states a time to firm set of approximately three weeks and a dry time of 7 to 14 days.¹³^•¹⁶^•¹⁴ With paint-coat maintenance, DAP '33' Glazing is rated for approximately 15 to 20 years of service.¹⁴

Putties harden and crack with age and need replacement periodically; a glazing compound, a related product with a formulation modified to remain plastic over a long period, is the alternative where a longer-lived plastic seal is wanted.⁵ Metal windows take a metal window glazing compound or butyl-based mastic instead of linseed putty.¹⁷

Putty and modern sealants

MS-polymer sealants, butyl tape, silicone, and acrylic compounds all compete with linseed putty, and the choice is decided first by the glass. Linseed oil migrates into the edge seal of a sealed double-glazed unit and degrades it, and attacks the interlayer of laminated glass, so traditional putty is confined to single panes of ordinary glass; for anything else the unit maker's specified sealant, tape, or a tested MS-polymer product is used.³ Silicone is a proper bedding material for sealed units but a poor putty substitute: paint will not adhere to it and it cannot be knifed to a sharp arris.³

Where putty still holds its ground are cost, repairability, and conservation. At 3 to 5 meters of fronting per kilogram it is the cheapest material on a large job, roughly an order of magnitude below cartridge sealant; a putty fillet can be cut back in sections and re-faced repeatedly, while a skinned MS-polymer fillet must be cut out entirely; and a knifed linseed fillet is what conservation officers expect on listed buildings.³ In Britain, linseed putty remains the default on single-glazed timber windows, made to the recipe of BS 544:1969, a standard now withdrawn but still quoted on data sheets.³

Plumber's putty and other varieties

Plumber's putty is a soft, malleable compound of clay and linseed oil sold in tubs or paper-backed rolls, used to set fixtures, faucets, sink frames, sink basket strainers, and shower drains. It creates water-resistant seals with no cure time and stays flexible, but it is not an adhesive: it is water-resistant rather than waterproof, it degrades plastic, and unstained versions are needed for porous stone. It costs $2 to $5 per tub, against $8 to $20 per tube for silicone sealant, which cures in 24 to 72 hours and bonds to plastic, metal, glass, natural stone, and wood.⁴

Other varieties serve different trades. Wood putties fill holes, corner chips, cracks, and screw holes in joinery.¹⁸ Cement-based wall putties level and smooth concrete and plastered walls before painting.¹⁹ The word itself has a second, older sense: putty powder, an abrasive of finely divided tin oxide (sometimes with lead oxide), used for polishing glass, marble, and metal.¹^•²⁰

History

The glazier's cement has a long pedigree. The 15th-century artist Cennino Cennini recommended a cement of varnish and white lead for mending ceramics and glass, colored green with verdigris if the glass was green, and "putty" appears to have been commonly understood as linseed oil with chalk or white lead, often both, for at least a few hundred years.⁹ An 1850s building encyclopedia calls putty "an important and indispensable article in the glazier's trade, ... composed of whiting and linseed oil."

²¹ Repairs made with white lead putty and staples are encountered so often by conservators of ceramics and stone that an 1896 writer remarked that anyone claiming to have invented the method "might as well apply for a patent for having discovered the art of mixing brandy with water"; the drawbacks of the old method were the staples and rivets needed to hold objects together while the putty dried, and the seepage of linseed oil into porous objects, causing staining.⁹

The whiting supply became an industry of its own. Whiting has been produced in England since the medieval period, and since the 18th century it has been a major component of linseed oil putty; by the 19th century chalk was being crushed on an industrial scale, as at the whiting works at Hessle on the Humber, built between 1810 and 1815 around a windmill, where chalk was crushed and levigated into whiting shipped away by water.²² In conservation practice today, deteriorated putty is removed manually or softened with heat, linseed oil, or chemical strippers, the glazing channel is primed, and the glass is reset in a fresh bed of putty; on valuable historic glass, aggressive prying or open flame are avoided.¹³^•²³^•⁷

References

Topic: Encyclopedia › Technology and the built world › Architecture, buildings, and civil works › Architectural knowledge and practice › Construction practice and materials

Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 15, 2026 · Edited: Oct 15, 2026 · Last review: Oct 15, 2026

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