Once the glass is secured with tiny glazing points (push pins), you take a fresh handful of putty. You roll it, knead it with your palm to warm it, then press it firmly against the glass and the wood frame at a 45-degree angle. The goal is to fill the entire void—no air pockets.

While modern homes often use synthetic sealants or rubber gaskets, putty remains the gold standard for wooden and some metal window frames because it allows for the natural expansion and contraction of these materials without losing its seal. Choosing the Right Putty for the Job

Traditionally, glazing putty is a simple mixture of (finely ground chalk) and linseed oil . Over time, the oil oxidizes and the mixture hardens into a durable, protective bead.

The use of window putty dates back to ancient civilizations, where artisans used natural materials like plant resin, beeswax, and lime to seal glass panes into wooden frames. The earliest recorded use of glazing putty was in ancient Rome, around 100 AD. As glass-making techniques improved, the need for a reliable sealant grew, and window putty became an essential component of glasswork.

Fresh putty looks like clay. Paint it immediately, and the solvents in the paint will trap the linseed oil inside. The oil has nowhere to go, so it weeps out through the paint, creating yellow, sticky "bleeding" stains that ruin the finish. Worse, the trapped oil prevents the putty from ever hardening—it remains a soft, gummy mess.