What is putty

What Is Putty?

Putty is a malleable, paste-like compound used primarily in construction and repair work to fill gaps, seal joints, and hold glass panes in place. The most common form is window putty, which has been used for centuries in traditional glazing. Its smooth, workable consistency allows installers to press it into place, where it gradually hardens to create a weathertight seal.

Composition and Properties

Traditional putty is made by mixing chalk powder with boiled linseed oil and sometimes additives like turpentine or pigments. This combination creates a putty that remains soft and pliable at room temperature but hardens through oxidation when exposed to air. The consistency is thick and clay-like, allowing it to be kneaded and shaped by hand. Modern putties may include synthetic oils or polymers for improved performance.

Uses of Putty

Window putty is primarily used to seal glass panes into wooden window frames. It creates a weathertight seal that prevents water infiltration and air leakage. Beyond windows, putty is used to fill small holes and cracks in wood, plaster, and other materials. Wood filler putty, glazing putty, and flexible acrylic putty serve different purposes depending on the application and surface type.

How Putty Hardens

Putty hardens through a process called oxidation. When exposed to air, the linseed oil undergoes a chemical change that causes the material to solidify. This process typically takes 1-3 weeks depending on temperature, humidity, and putty thickness. The hardening is not instantaneous like caulk, so premature stress on the putty should be avoided.

Application and Removal

Putty is applied by pressing it into joints and gaps, then smoothed with a putty knife or hand. For window glazing, it's applied in a bead around the glass perimeter. Once hardened, excess putty can be trimmed away with a knife. Removing old hardened putty requires careful scraping and sometimes heat to soften it first.

Modern Alternatives

While traditional putty remains popular in restoration and traditional work, modern alternatives include silicone caulk, acrylic latex, and expandable foam. These alternatives often provide better water resistance and flexibility, though they lack the traditional appearance and reversibility of putty.