Bowing and sagging panel
detached brass bar ties
Rattle when panel is tapped.
Broken solder joints or lead.
Bowing or sagging in the panel.
Wind,rain or light leaking through the structure.
Detached reinforcement bars ( if present).
Generally leaded glass panels should be firm to the touch. The first thing I do when when assessing condition is to give the glass a quick tap with the palm of my hand. The panel should resist the tap without rattling. If the panel does rattle then something is wrong and could be addressed, but before looking at the panel itself check the putty or beading holding the panel in the window or door rebate. A gap here can cause a rattle and a simple bit of putty in the gap can stop this.
The most common reason for a rattling panel is the loss of leaded light cement. This cement/putty is brushed into the lead structure of the window after it has been constructed, rather in the manner of grouting tiles. The main purpose of cementing is to weatherproof the panel but it also provides at least 50% of the finished strength, so it needs to be there. Looking at the areas where the lead meets the glass, if you can see long gaps under the lead with no cement then the panel probably needs recementing.
Generally fixed window panels suffer from very few structural problems. Occasionally bagging may be seen toward the base of the structure due to a mixture of bad construction and an overly heavy panel or bowing in the centre due to agressive window cleaning . Door panels on the other hand often show structural damage, although only after the first sixty years or more. This is where you will be more likely to find a loss of cement, leading to rattling and eventually to broken joints etc.
Virtually all structural problems in door panels are due to a mixture of door slamming and quallity of construction. Even when a door is closed mildly the centre of the panel oscillates back and forward and this puts a fair amount of strain on the leadwork. Cracks may appear between the solder joint and any lead run. These can be resoldered as they are usually due to a hardness differance between the lead and the solder joint being shocked over and over again. Cracks in the main lead runs are usually due to the lead 'work- hardening' from flexing and eventually becoming brittle. These leads should be replaced on a bench either as a repair or as part of a full restoration .
Door and window panels are often fitted with reinforcement bars. These are usually on the inside and secured to the leadwork with brass ties. They limit the amount of back and forth movement, but eventually the brass ties connection with the lead can also break .
Stained glass repair as you will have gathered come in a number of forms and these are covered in the next page - Repairs and restoration