Introduction
Stained glass windows provide historic charm, stunning visuals, and often increased property value, but they aren’t completely without faults. Over time, often invisible damage builds up until you start to notice cracks in the glass, faded paint, and damage to the surrounding lead.
Cheap, quick fixes and poor-quality restorations can worsen the damage and affect property value, as well as lead to further repairs down the line. In this article, we will explain how to restore stained glass windows safely, what the right tools and techniques are, and when it’s time to bring in the professionals.
Understanding Damage in Stained Glass Windows
The nature and extent of the damage will determine whether you can fix this yourself or whether you require a professional stained glass restoration. Below is a breakdown of the types of stained glass issues that need repairing:
Lead Fatigue
This is when the lead that connects stained glass panels begins to weaken, crack, or bow. This is caused by repeated expansion and contraction from temperature changes and normal wear and tear over the long term. You can spot the signs of lead fatigue/bulging by checking for loose, rattling panels, seeing if any light is coming through the lead, and from visible changes to the lead, like cracking.
With lead fatigue, it may just be one area that is affected, however, it is more likely that the entire window is experiencing pressure on the lead framing as a result of aged stained glass and long-term wear and tear. While repairs may be made to individual frames, expect that you will need to keep making these minor repairs and it is advisable to enlist a professional to assess the entire window and determine whether a full-scale re-leading is necessary.
Cracked or Missing Glass
If you notice cracks in the glass or broken/missing pieces, first take care to not cut yourself when touching the glass, but do try to save as many glass fragments as you can. It may be possible to reattach these pieces, but in cases where the damage is too extensive, the original pieces will still be useful in identifying colours and compounds needed to help create a seamless replacement or with any paint touch-ups.
Hairline cracks may be easily repaired, missing pieces will likely require professional assistance, and larger cracks will depend case to case, but we recommend speaking to a professional in the first instance, just to be safe.
Paint Deterioration
Paint deterioration will occur naturally over many years and may not be noticeable for quite some time. This issue is more common for south-facing stained glass windows as these receive sun exposure for the majority of the daytime. Specialist compounds and techniques are required, as well as professional experience, to resolve this issue. As it is more for restoration purposes than general repairs, we do recommend hiring a professional.
Step-by-Step Process to Restore Stained Glass Windows
Below is a full breakdown of all the steps that may be necessary when performing a full restoration. While some of these steps may be done yourself, the majority would require professional assistance.
1. Inspection and documentation
When you first become concerned over damage to your stained glass window, be sure to photograph everything; you will need photos of the inside and outside of the window, and close-up pictures of damaged areas. Make sure to take photographs regularly, to show if the damage has progressed in the time between first spotting it and having it repaired. This will help when it comes to repairs but may also be necessary for your insurance.
2. Removing the panel (if necessary)
If the damage cannot be repaired as is, it may be necessary to remove the window entirely so that it can be repaired in a workshop, safe from outside elements.
3. Cleaning the glass
Each piece of glass will need to be properly inspected and cleaned before it’s ready for repairs. This includes removing the old lead (if necessary), and cleaning off any adhesive, dirt, and sediment so that it doesn’t become trapped in the repaired glass.
4. Repairing cracks
For a minor repair to hairline cracks in the glass, you can do this yourself with epoxy glue by applying it carefully to the cracks in the glass.
For panels that have come loose, silicone can be applied to adhere the panel to the frame to secure it, however, not all silicone-based products will be appropriate, and you should always check with a professional for the correct product.
Alternatively, the copper foil technique can be used, which involves wrapping the borders of the glass panels in copper foil and soldering them together.
5. Replacing damaged pieces and re-leading
When replacing repaired glass pieces, they will need to be carefully put back into position and secured, ready for re-leading. Re-leading is the process of removing all existing lead and applying new lead to secure the panels together. This typically occurs every 50-100 years depending on the window, location, and the quality of the leading.
6. Cementing and waterproofing
A specialist compound is added to the releaded window to provide a protective seal on the newly-applied lead and assist in waterproofing the window. Moisture ingress can be very damaging to stained glass windows so this is a vital step.
7. Reinstallation
Where the window panel was removed for repairs, it will need to be carefully reinstalled to its original setting, taking care not to damage the glass, to correctly reseal any gaps, and to not cause any abrasions to the window paint.
Common Stained Glass Repair Techniques Explained
We have already covered off various methods for repairing stained glass windows, and below is a more detailed look at the most commonly used techniques:
Epoxy Edge-Glueing
Epoxy glass repairs are useful for small repairs which are nearly invisible once made and are relatively strong. Once dried, epoxy is difficult to remove, so may cause issues if greater repairs are needed later.
Silicone Repair
When glass breaks or comes loose, silicone can be applied to reattach those pieces. It is not as strong as other alternatives, but it is more forgiving; it’s flexible and breathable which is helpful when window panes expand and contract in heat, and it is easily removed if needed down the line.
Copper Foil Repair
This is a more traditional stained glass window repair, but it is still popular today as it is strong, reliable and minimally noticeable. It involves edge-wrapping the glass pieces in copper foil, connecting them to other pieces, and soldering them together.
DIY vs Professional Stained Glass Restoration
It’s not always necessary to hire professionals to complete repairs on your windows. Here, we’ve outlined which issues may be fixed yourself, and which require a professional stained glass restoration.
When DIY Is Safe
· Fixing minor cracks in windows with epoxy glue is something you can do yourself, as long as you’re careful to clean off excess glue before it dries, as this will affect the look of your stained glass.
· You can carefully clean old, dusty stained glass windows yourself, provided that you do not use anything abrasive on the glass that may damage the paint.
· If you have access to the right tools – and safety equipment – you can perform small solder repairs using the copper foil method, to secure loose panels. Please be very careful doing this as you can get burnt from solder, and as messy soldering will be very visible on the window.
When to Hire Professionals
· Whatever the issue, if the repairs are for historic or listed buildings, you absolutely need to seek professional restoration in order to comply with the regulations of that property and to preserve the quality and aesthetic of the glass.
· If there is severe structural damage, it may be necessary to remove the entire window panel, in which case you would need professionals to understand these repairs.
· For restorations to painted glass specifically, you need a professional as specific compounds must be used to match the original, and must be painted on very precisely. It is a delicate and meticulous process that needs expert care.
Cleaning and Maintaining Stained Glass Windows
As mentioned above, cleaning is an effective way to look after your stained glass windows that you can perform yourself.
When cleaning stained glass windows, the most important thing to remember is ‘less is more’. Use mild soap, soft cloths, and avoid harsh chemicals like ammonia. It’s better to do a passable job at cleaning the windows than to risk scratching the glass and damaging the paint/images.
Regular maintenance is also an important step you can take to look after your windows; checking both the exterior and interior sides of the glass every couple of months will help you catch problems early and prevent them from escalating. You should also consider applying a protective glazing coat to the glass, and ensuring proper ventilation inside the property – this will protect against external weather and internal condensation damage.
If you need more guidance, read our full blog on how to care for your stained glass windows.
Conclusion
Preserving and restoring stained glass windows requires care, patience, and a degree of skill. Although there are plenty of minor repairs and forms of maintenance you can do yourself, many other repairs require a professional hand.
The best thing to do if your window is damaged is to properly identify and document what the issue is, then assess the type of repair required to fix it safely, effectively, and without causing any further damage. If you are aware of any damage to your stained glass window but aren’t sure how to proceed, please get in touch so that we can perform an inspection for you.
