How to reinforce stained glass is a question I get asked over and over and OVER 🙂 Sadly, there isn’t a ‘catch all’ answer. T‪here are many different factors to take into consideration when reinforcing stained glass windows and they’re different with each window.

When To Reinforce Stained Glass Windows

‪Here are a few of the factors you need to take into consideration:

The Design

This is the most important. If it’s balanced with a mixture of large and small pieces of glass, with lead lines both vertical and horizontal your window will be inherently stronger and need less reinforcing. This is the ideal situation!

‪The Frame

The best solution for stability is 1/2”/12mm puttied lead came around the edge and then fixed in a wooden frame. You can use zinc if you prefer but it’s more time consuming and a bit of overkill if you have a wooden frame too.

‪The Position

Is your panel internal or external? South or north-facing? These are all important things to take into account when reinforcing stained glass windows.

‪I use the following as a general guide:

  • ‪Panels that are static – and by that I mean an opening window or door = perimeter more than 10ft needs reinforcing (some say 12 ft but it’s always better to err on the side of caution)
  • ‪Panels that move – a window or a door = perimeter more than 8ft needs reinforcing.
  • Add reinforcing right across your panel every 18″/450mm or so. It can’t stop halfway across, mind! It has to go from edge to edge for strength.

The bottom line is that reinforcing solutions vary greatly depending on your design and window location.

Main Methods of Reinforcing Stained Glass

how to reinforce stained glass

There are many different ways of reinforcing stained glass windows. These are the main groupings:

1. Metal Strips

Copper Re-Strip, Morton Strongline or Flex-Bar, a braided copper strip. They are collectively referred to as ‘Fins’. They are inserted in between foiled shapes or next to the heart of lead came (not braided wire for lead) and are bent to shape. They can crisscross your panel.

You can get them on Amazon here:

Copper Re-strip*

Morton Strongline*


(*Just so’s you know, if you click and buy through the * links within 24 hrs I get a small % from Amazon, (not you!). Thanks in advance but no worries if you have a local store – I’d always support them first 🙂 )

2. Lead Came

There is also reinforced lead came available that comes with a thin strip of brass or steel running through the heart of the came. This doesn’t bend easily and is good for straighter lines and larger panels.

3. Metal Rods

Saddle Bars are round metal rods added after the piece is assembled. They are drilled and fixed into the window frame and copper ties soldered on the stained glass are twisted around it. Alternatively Flat Rebar are flat metal rods which are soldered on to the face of the came in place on the inside of the panel to keep the entire work from flexing.

Methods #2 and #3 are generally used for reinforcing large external or moving stained glass windows. Techniques #1 – Metal Strips – are more usually used for copper foiled work so I’ll concentrate on how to reinforce stained glass with these.

How To Reinforce Stained Glass

reinforcing stained glass windows

Placement isn’t too difficult if you remember these rules:

  1. The strongest reinforcement runs the shortest distance from edge to edge
  2. Reinforce perpendicular to a lead line that might fold. Parallel lines and borders are good examples

Reinforcing Stained Glass Using Re-Strip & Strong Line

Copper Re-Strip

The Re-Strip* is 10 mil thick and has a bit of a life of its own. You can see it being used in the left-hand panel, above.

  • Re-Strip does sit higher above the glass a little but this is hidden once you solder the seams. Georgia used this to her advantage because the centre plate that it supports was heavy and stuck out quite a bit from the panel.
  • She soldered the backside first so that the circle was proud at the back and not the front of the panel.
  • Pins were used to hold the Re-Strip in place. You can use masking tape across the top of the glass instead of pins to stop it from popping up.
  • Lightly tack solder it in as you work it around.
  • Use bent nosed pliers to bend it around corners.

Pros and Cons: Re-Strip can be used with Lead Came. It’s effective and invisible. Some people find Re-Strip a bit difficult to bend as it’s very stiff.

Morton Strong Line for Reinforcement

Morton Strong Line*  is heavier than Re-Strip at 20 mil thickness.  It jumps about a bit as you are assembling your stained glass panel. You can try using horseshoe nails to keep the end you are not working with in place so it doesn’t jump around.

As with the braided wire (below), you have to shave a mm off your glass piece to accommodate the width of the Strong Line. This is to stop  your panel growing bigger than your pattern. Not desirable!

Strong Line is good for panels that have straight-ish lines and that don’t have many complex shapes to bend around.

Pros and Cons: It’s very strong and effective. It can be used with lead came. It’s a bit tricky to manipulate but makes up for it in strength!

how to reinforce stained glass - restrip

Using Flex-Bar for Reinforcing Stained Glass

Flex-bar is a braided copper reinforcement originally used for reinforcing lamps. The solder drips into it and stiffens it during assembly.

Georgia used it for stiffening and reinforcing across the centre of the panel, right above. The blue line shows roughly where the braided reinforcement was placed.

  • It is the same height as the glass so it didn’t matter which side of the panel I tack soldered it into first.
  • It is wider than Strong Line or Re-Strip so you’ll have to work out where it’s going to go BEFORE you cut your glass. Cut the glass a bit smaller along this reinforcement line to leave more of a gap to accommodate it. Because of this, it makes your solder seams wider, which may bother you.

Pros and Cons: It’s easier to use than Strong Line or Re-Strip as it’s more flexible and good for complex lines. Good for arthritic hands! It uses far more solder and creates a wider solder seam.

Which Metal Strip Is Best?

I think all three have their uses, depending on your design.

Using Strong Line, ReStrip or Flex-Bar next to the heart of the came as reinforcement is great choice because it’s internal and therefore not visible from the outside like saddle bars or flat rebar.

You can get them on Amazon here:

Copper Re-strip

Morton Strongline


(Just so’s you know, if you click and buy through the links within 24 hrs I get a small % from Amazon, (not you!). Thanks in advance but no worries if you have a local store – I’d always support them first 🙂 )

Reinforce Larger Stained Glass Panels With Metal Strips

With these Strong Line or Re-Strip solutions I would:

  1. choose 1 or 2 straight-ish central line/s (depending on the height of the panel)  and cut the metal strip a couple of inches longer at each end.
  2. bend the strip upwards at either end a couple of inches and solder these ‘tails’ into the lead or zinc frame.
  3. melt some solder in the inside of the frame to hold the metal strip in place. Do this by working it in at the solder joint along the area where the braided wire is sitting.

This effectively holds the weight of the top half/third of the panel above the reinforcement line.

Big thanks to Georgia Hamilton for sharing her helpful storyboards for this page 🙂 Georgia is a student of my online stained glass classes and a member of my private student FB Group the Stained Glass Hub.

Reinforcing Questions

Question: Should the reinforcing go horizontally or vertically?

My rule of thumb:
  • The basic principles are if it’s a tall narrow window, go across with the reinforcing.
  • If wide and short, go vertical.

Beach Design




Question: When I solder the panels together do I need to reinforce the panels before soldering? If the answer is yes how should I do that?

I have designed and created 3 stained glass panels separately and now want to put them together to make a single rectangular panel for a transom window 66″ in length (actually I am doing 2 windows). Each single panel is 22″ using foiled technique. I plan to go around the perimeter with U came.

I have attached my design that measures 10 7/8 x 66. There are (3) panels. Starfish, Chairs, and Starfish again. This will be placed on the inside of the transom windows using silicone or small window molding.

Milly’s Reply:

I would add 2 vertical supports (as per the turquoise lines). Make them longer and solder them into the U came frame. See instructions above under Reinforcing Larger Panels With Metal Strips.

The moulding will give the edge some support too.

Question: Saddle Bar Attachments

I’m fitting some restored stained glass panels into new wood frames. The panels are roughly 1m 26cm (4ft 2″) high so I’m fitting saddle bars horizontally in either 2 maybe 3 placed to tie the panels too. How do I fit the saddle bars to the framework? Should I just make the saddle bars the width of the window and once the panel is tied would that be sufficient?

Milly’s Reply:

Work out where you’re going to place the saddle bars and drill 2 (or 3) holes on both sides of the wooden frame, one about 2.5cm deep, the other less, say 1.5cm. Their diameter must be big enough for the rebar to go in.

Then place the window in and insert one end of the rebar into the deeper hole and then centre it so that there is an equal amount of rebar in each hole.
You can wedge them in with small slithers of wood and/or putty around them and paint when dry.

No, you can’t have the rebars the exact same width as the window. They have to be cut longer and go into the frame to add strength.


Other stained glass tutorial articles on the site that might interest you:

Stained Glass Tools and Equipment

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