With the development of double glazing and PVC window frames old wooden sash windows have almost completely disappeared. In some cases though wooden window frames still exists, sometimes for their aesthetic look and sometimes because of building restrictions. Wooden window frames though are not everlasting and one of the first things to become damaged is the putty that keeps the window glass in place. Is it though possible to mend cracked putty?

Traditional window putty has been linseed oil putty, and though easy to work with does over time become brittle and will crack. As putty becomes brittle it is also likely to fall away from the window frame, leaving the dangerous possibility that the window glass will fall out. Even if the putty does not fall away the crack that appear in it will start to allow water to penetrate into it and ultimately will start to cause the wooden window frames to decay.

In essence putty cannot be mended and can only be replaced. Gaps in cracked putty can be filled with new putty, but if parts are cracking then it is likely that all of the putty will crack in the near future.

Replacing putty though is relatively easy and anyone with basic DIY skills cannot do the job, as long as care is taken. Removing cracked and old putty is any easy task, although always look out for old glass nails or panel pins that are in place to hold the window glass in place.

It is then a case of coating the wooden window frame in linseed oil or similar product. The linseed oil helps to ensure that the putty remains workable whilst finishing off is undertaken. The putty itself needs to be worked to make it soft and pliable enough to position it between the window glass and the wooden window frame. With the glass in position the putty then needs to be smoothed around the frame with the use of a putty knife. The putty knife will also help to remove any excess putty. The putty then needs to be allowed to dry and harden at which point additional protection can be given to the putty with the use of paint or varnish.

Traditional linseed oil putty has been somewhat supplanted in recent years with synthetic putties, elastic and pliable but without the eventual brittleness.

Whilst it may not be possible to mend putty, replacing it is a relatively simple process.

Learn more about this author, Tim Harry.
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