Window putty or silicone?


If old, single-glazed windows are to be renovated, recapping the glass panes is essential for a sufficient seal. Whether you should use classic window putty or better silicone, and what other alternative there is, read in this post.

Window putty composition

The classic window putty or glaze putty consists of more than three quarters of so-called whiting chalk. Whiting is pure calcium carbonate, so it is practically limestone.

The rest of the mass is linseed oil varnish. It is obtained from the linseed oil, which has been modified by certain processing methods in its drying properties. During curing, it forms a kind of "paint" form.

This composition has been known since about 1700 and has been respected ever since. The kneadable paste always has the same composition.

Only in the decades before 1990, asbestos fibers were added to the putty. This putty is not commercially available today, but when removing old putty you have to be careful because asbestos can cause dangerous lung damage.

natural product

Since today the classic composition without asbestos addition is on the market, window putty can be regarded as a pure natural product. Silicone is a 100% chemical product.

Disadvantages of classic putty in comparison to other sealing materials

The biggest problem of the putty is that it starts to become brittle after drying out after a few years. He can then crumble and does his job, the glass to hold and seal the glass no longer properly.

This can also cause leaks on the wooden window, and it can train occur. The already only very poorly insulated single-glazed wooden windows then still allow much more heat outside, in addition, condensation can occur.

A new installation of the discs every few years is therefore indispensable when using traditional putty.

Advantages and disadvantages of silicone

Although silicone is a durable and very durable sealing material, the application to the glass edge is very difficult and requires a lot of skill. In addition, silicone can be a good breeding ground for all kinds of bacteria. As a result, it also turns ugly over the years.

An advantage, however, is the fast drying time. Silicone hardens in less than a day, putty dries in about 2 - 4 weeks and can only be painted over after about 6 weeks. Silicone, on the other hand, can not be painted over.

Tips & Tricks

A good solution is provided by synthetic plastic-based sealing materials. They are also easier to use than silicone.


Video Board: How to Glaze a Window Sash