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Leadlighting Tutorial Lesson 8: Reinforcing - how, when, where and why.

The function of reinforcing is to strengthen the leadlight to prevent bowing or bending due to wind pressure or shock, as in the slamming of doors. (A door in a draughty area is the hardest place for a leadlight to survive – a good idea is to fit a door closer.)

A leadlight must be reinforced when BOTH dimensions exceed 500 mm.

EG, if the leadlight is 2 mtrs high and 500 mm wide, as in a side-lite, reinforcing won’t be necessary, but if the leadlight is 2 mtrs high and over 500 mm wide, reinforcing will be necessary. Wherever possible, try to have the reinforcing extend across the shortest dimension, but the design can influence which way to have it.


The above drawing represents combinations of front entry doors and side-lites. All door panels with large openings must be reinforced to offset slamming (the older style doors that have large openings 5 - 600mm square.) The modern, narrow type no, (usually consisting of two panels about 1 mtr x 250 mm) but still be careful of slamming.

The side-lite at the right in the above diagram, being 800 mm wide certainly needs reinforcing and because it is full length (2 mtrs high) and quite large, two reinforcing lines at the 1/3 mark will be required at least. However suppose you had a panel about half this area, let's say 940 x 450 mm, you could use one reinforcement line at the half-way point if you are worried about it, but it really isn't necessary. (See side-lite panel size on the left in the above drawing.) If the design is such that the straight line of zinc would spoil the design, see further down for the way around this problem.


A diamond design, although a very traditional design, is the weakest design that can be made simply because there is a point on a point with no natural reinforcing by design. In a natural sense, you can imagine if bricks were laid one on top of the other in a straight vertical line, the wall would not be as strong as bricks that are staggered and interlocked. It's the same with a diamond design. When suffering wind pressure, they tend to bow. Depending on size, every second or third lead can be replaced with zinc to give strength to a diamond panel. (Use the same size zinc and lead for uniformity.) Squares and rectangles are similar.


For ‘correct aesthetics,’ a diamond should be drawn twice as high as it is wide. Avoid a rotated square, it isn’t good design. Also for most windows it should contain a certain number of diamonds.

If the widow is a rectangle twice as high as it is wide, or nearly so, divide both sides by 4 on the inside line. (See diagram further down.) If the window is a square, divide the height by 4, width by 8.

If the width of the window is between 2/3 and 3/4 the height, i.e. a little less than a square divide the height by 4, same as the other sizes, but the width by 6. This formula works for just the right amount of diamonds in any size window and will give the same 'scale' as in shape to the diamonds. However, if the window is a rectangular shape and horizontally, e.g. a transom window above a door the rule can't be followed here. You'll need to decide how many diamonds can you draw in the design in the height and look sensible, still remembering the 'twice as high as it is wide' for the shape and size of the diamond or as close to as possible. Lets say the window is a certain height that putting two diamonds high makes them look too small but only one diamond high and it looks a little too big, you can overcome the problem with a border, which will effectively reduce the size of a single diamond in the height. Once you've decided on which way to go the next thing is to multiply the width of the diamond and see if they fit in the available width of the window. You may need to adjust the size of the diamond in its width accordingly.

(In some small rectangular kitchen cupboards, particularly with a border around the diamonds, dividing the height and width by 4 may possibly make the diamonds too small, dividing both sides by 3 gives a better size. If you have a look at a photo in Lesson 2, you'll see what I mean.)

When drawing the cartoon, draw in the outside, cut and inside lines (The inside line represents the total width of the outside lead.) This is so that when you draw in the diamonds, you will be aware of stopping each point at the inside line, thus retaining the design, the points not disappearing behind the lead, which is very poor design to a diamond panel. (See diagram below.) However, if the design has a border around it, it’s not necessary to draw the inside line as the internal leads are smaller than the outside lead.

Diamond designs traditionally use clear glass all over, but there are many things you can do to create interest. If it isn't necessary to see through the window, random light pastel shades are very nice and is a favourite of mine. Another thing you can do in a clear diamond panel, the 4 diamonds in the centre can be changed to a different clear texture adding more interest to the window. Another thing, suppose the window was a rectangle, at the design stage and before you ink it in, draw an oval in the centre then rub out the diamonds within the oval and there are any number of things you might want to design in the oval. A family crest, if it's an easy one, or a simple shield with a diagonal bar across it is effective. One or two roses (one overlapping the other) with leaves is always nice. Draw the oval slightly larger than the 4 diamonds in the centre. (You can imagine this in the diamond diagram below.) If the window is a square, a circle will look better. All it needs is a little creativity to change what some consider not so exciting.



Begin by design, i.e. consider where to position the reinforcement lines, eg. if you are making a front door panel with roses as the theme, you wouldn’t want a horizontal line going through the roses. Draw two vertical lines either side so as not to spoil the design, and as this is a traditional design these vertical lines can easily be disguised in the rest of the design.

If you know the panel has to be reinforced this is the third thing to draw on the cartoon. By drawing the reinforcing line first, it's easier to design the rest rather than drawing the design first then wondering where to put the reinforcing line. If you only need one reinforcement line, try to draw the design with this line as close to the half-way point to effectively do the reinforcing. If you were designing a ‘seascape’ design, use the reinforcement line as the horizon, or close to it to disguise it. (See rough diagram.) Wherever using zinc, draw the cartoon cut line the same size as you would for lead. Again and as always, try to think ahead in the planning stages of your designs.

Remember too, that puttying properly effectively helps reinforcing.

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Never consider using external reinforcing, as it will not go the distance. (The older method having a steel rod connected to the leadlight with wire as in churches and some older front doors.) The wire is soldered to the lead where the rod crosses them and then twisted around the rod, but with constant slamming the wire breaks out of the solder. In most cases with front doors, the rod is on the inside, which is the problem and why it comes adrift when the door slams. If it was on the outside it wouldn't happen as it would support the leadlight from wanting to continue forward.

Recommendations: The best and easiest reinforcing to use is zinc and is available in various sizes. It is usually used in a straight line in the design, however it can be bent with care. A hacksaw is used to cut the zinc.

(Another thing you can do although I don't recommend it, is to use a flat steel bar against the heart of a lead that spans across the leadlight, in between the heart of the lead and the glass. This flat bar is 4 x 1 mm and is usually inserted in a twin heart lead called 51 H, but it can be used as described against the heart of a lead. You can understand that when installed in a leadlight, it's strength lies in the flat plane resisting bending. If using against the heart, remember to add 1 mm to the cartoon line to accommodate the flat bar or you will cut your glass too big. The reason I don't recommend this is because this steel flat bar is rusted when you put it in and continues to rust until it eventually breaks down by disintegrating and swelling up and I have seen it when pulling old leadlights apart. Even if it is used in a 51H lead it will continue to break down and rust. The 51H lead has twin hearts and the steel bar is slid between the hearts.

If you can get a flat brass bar the same dimensions, that is OK, the brass won't rust and you can use it either in the 51H lead or against the heart of a normal single heart lead. If you do use a 51 H lead, remember there is the thickness of both hearts plus the brass bar totaling 3 mm, but you had best allow at least 5 mm for the cut line as there is a wider space where the metal goes. The overall width of the 51H is 9.5 mm, which may look too large for your application - you may be better off to simply use the brass bar against the heart of a normal lead, or even simpler, use zinc. Sometimes a leadlight in a high wind area and of a large size necessitating the use two or more zinc cames to give the required strength, putting a brass bar as mentioned above next to the heart of the zinc will give added security to the leadlight. If you decide on this avenue remember to draw a 2 mm cut line to accommodate the heart of the zinc and the brass bar. It is best for strength reasons to have the reinforcing across the shortest dimension of the window.

Other reinforcing methods.

There are some designs that would be spoilt by the straight line of zinc. A reinforced heart lead can be used to overcome this problem and they are available in four face sizes. These leads contain a brass insert in the heart to effect the reinforcing. When drawing the cartoon, use a 2 mm line for the cut line for these leads, as the hearts of these leads are 2.1 mm thick.

Advantages: Easily bendable, conforming to most shapes, ideal for designs where the straight line of zinc isn’t wanted.

Disadvantages: Must use a hacksaw to cut, which tends to mutilate the lead, use extra care when assembling and soldering. Never use your snips, as the brass insert will destroy your snips in one go.

Liquid flux.

Liquid flux.

Stearine flux.

Stearine flux.


Zinc is required to be completely free from oxidisation to effect a good join. Obtain a medium cloth and vigorously clean the entire surface on both sides to a shine after cutting it to the length you want. The object is to scour the surface to act as a key for the flux, solder and patina to bond. Use Bakers liquid flux on the zinc, stearine flux on the lead as in the drawing above. With the second heat application (see Lesson 4) stearine flux is OK to use overall as the join has already bonded by use of the liquid flux.

Wherever using zinc, it must span across the leadlight (either vertically or horizontally) and through the outside leads for a timber window. This is so that when the beading of the window or door goes on during installation, the zinc is covered by the beads making it stronger still.

Note 1: Cut the zinc short of the outside leads by 2 millimetres or so that if trimming is necessary, the zinc won’t damage the blade of the plane. Lead planes very easily.


Note 2:The exception to this is an aluminium widow where the outside lead is a Y13. The zinc is butted to the Y13 just like all the other internal leads.



If the leadlight contains zinc it must be prepared so the surface will accept polish. After puttying and prior to using Black Patina, give the zinc another light rub with the emery cloth and be careful not to scratch the glass. Fold the emery cloth so that it just covers the zinc. Using a cotton bud, apply the patina liberally to the zinc and it will turn dark brown to black. Again, try not to let it spill on the glass, especially clear glass. After applying the patina on all the soldered joins and the zinc, wait the usual 20 minutes for maximum effect, or until it's dry and continue with the polishing.


If the leadlight is too big to make in one panel, eg. anything over a metre wide, the stack glazing method can be used. The leadlight is made in sections with a 6 mm U zinc on the top of the lower panel.

A 13 mm H zinc is used on the bottom of the next panel which fits over the 6 mm U zinc and hence joins and so on.

Just remember that both the 6 mm and the 13 mm zinc must extend across the full width of the panel in all instances so the panels will fit together.

This method can be used both vertically and horizontally. The leadlight is designed in one panel with a 2 mm line at the separation points, (remember there is the hearts of both zincs) but the leadlight is made in separate panels and joined at installation.

Nothing is used to seal or glue the panels together; they merely fit over each other with a tight fit so that they can be removed at a later date if necessary. You probably will never make a leadlight to this size, but you’ll know how if you do. The 10th leadlight photo in Lesson 1, which depicts a waterfall in a rainforrest scene and is over 2 mtrs high and 1.5 mtrs wide was made using the stack glazing principal in a vertical instance.



When photographing your work, it is best around mid-day so that the sun is not shining directly through the leadlight. Take the photo from inside, but don’t use a flash or have any lights on. If the camera has an inbuilt flash cover it with a solid masking tape if you can’t isolate it.

I wish you good luck and enjoy the hobby.




Leadlighting Tutorial Lesson 1: Cutting Glass for Stained Glass Leadlights the Right Way

Leadlighting Tutorial Lesson 2: How to make a leadlight. Get started with a simple clear glass leadlight. Design choice.

Leadlighting Tutorial Lesson 3: Assembly of a Leadlight and helpful hints.

Leadlighting Tutorial Lesson 4: Soldering a leadlight and using the right flux. Making a tinning pot.

Leadlighting Tutorial Lesson 5: Measuring and other things you need to know.

Leadlighting Tutorial Lesson 6: Advanced Glass Cutting - methods for difficult shapes.

Leadlighting Tutorial Lesson 7: Puttying and how to repair a broken leadlight

Leadlighting Tutorial Lesson 8: Reinforcing - how, when, where and why.


© 2010 John Jackson


Heather Jauncey on November 23, 2013:

Thanks so much John for your prompt reply! I appreciate your advice for future projects too.



John Jackson (author) from Australia on November 23, 2013:

Hi Heather,

Fortunately you are right on or just within the border of whether to or not to reinforce, so you've got away with it, but as your question is under the reinforcing lesson and obviously you would have read it, you will have the knowledge for future projects.

I'm assuming the panel is a fixed window and not in a door because of the size you mention and it will be ok, but if you eventually get round to making a door panel, please be aware it will need reinforcing, simply because of the stresses put upon it - as in slamming!

In any reinforcing considerations I don't recommend using external reinforcing simply for aesthetic and strength issues. Aesthetically it's ugly, strengthwise it's not the strongest. I prefer to reinforce internally with either zinc or brass reinforced leads.

Hope this helps and good luck in future projects and enjoy the results.

Best regards,


Heather Jauncey on November 22, 2013:

Hi John,

Your Tutorial has been most helpful! Thank you so much. I have a panel 910mm wide x 545mm high. This is how it will be placed. Do I need to reinforce? Unfortunately I have completed the project but before we install it, I am anxious to know if I have to apply external reinforcing. Any help you can give would be most appreciated.



John Jackson (author) from Australia on January 10, 2013:

Hi Matt,

You're very welcome, good luck in future endeavours and feel free to contact me if ever you need to.

Best regards,


Matt on January 09, 2013:

Thank you so much John for your prompt and helpful guidance!

John Jackson (author) from Australia on January 09, 2013:

Hi Matt,

I'm assuming this panel is probably either going in the front or back door of your home, which either way will have a lot of traffic.

First up, can you consider replacing a couple of leads with brass reinforced heart leads in strategic positions, which will effectively do the reinforcing and no-one would ever know they were there. If it is possible to go this way, just remember to make your cartoon line 2 mm in width to accommodate the extra thickness of the hearts of these leads.

Secondly, the main problem you will have with leadlights in doors is when the door is left open and it slams shut from a gust of wind, the leadlight wants to keep going, which imparts a lot of strain to the leadlight, as I'm sure you can imagine.

If the design is such that prohibits the use of brass reinforced leads, then I would strongly suggest you fit a good quality door closer to the door, which will solve the slamming problem, they actually work both ways, they close the door gently as well - then you can get away without reinforcing.

Hope this helps and thank you for the question.

Best regards,


Matt on January 09, 2013:

Sorry about that typo. I have a 65cm x 65cm door panel which I have designed and partially cut. It's not reinforced. John, this may sound like a silly question (given your 50cmx 50cm rule, but do you think I could get away with NOT reinforcing it?!

John Jackson (author) from Australia on December 19, 2012:

Hi Andrew,

Firstly thank you for your kind words of appreciation and I'm just glad you find them useful and secondly, welcome to the hobby.

I'm also very glad that you have made a practice panel, you will reap the benefit of that - it's better to learn from any mistakes in that than jumping in at 'the deep end' first up.

Thank you for telling me about amazon, I didn't know that and I may delete all that information from the notes. If they don't want to supply, there's no point in advertising for them.

If I may ask a question regarding the notes, particularly Lesson 5.

I have agonised over certain parts in whether it is written in a way that is easily understood by the beginner. Could I take advantage of your expertise in carpentry and ask you to have another look at the contents of this lesson and if there is anything that you think could be improved on or changed to make it more easily understood, I would be very grateful. You can contact me by email: if you wish and feel free to contact me at any time with any question.

There is another fellow in QLD who has a Queenslander and has also read the notes like yourself and he is about to make some leadlights for his house.

Again my appreciation for your kind words Andrew.

Good luck with everything and best regards,


Andrew on December 19, 2012:

Hi John,

I firstly want to say thank-you for the excellently prepared tutorial notes on leadlighting. As a trade teacher of carpentry I can appreciate the hard work and devotion that has gone into preparing them. It is a real skill to write in a way in which a learner can easily understand and interpret.

I have been wanting to get into leadlighting for quite some time as I have some leadlight windows (diamond design) at the front of my Queenslander house which are on the point of collapse.

Thanks to you tutorial I have now gone out and purchased all the tools, some materials, and made up my first practice panel.

Regarding using amazon for purchasing the tools required, there suppliers did not want to supply, maybe Australia is to far away.

Thanks again for the notes, I am sure they will be reread and refereed to as I continue to lean this beautiful craft.


Andrew in QLD

John Jackson (author) from Australia on June 05, 2012:

Hi Sheryn,

Firstly, thank you for your kind comments - I just loved teaching the craft, even through these tutorials and I hope this experience hasn't put you off learning it as it really isn't difficult to do.

Secondly, if the cabinet was undamaged when you paid for it, it is really their responsibility to 'make good' for you - even if they were to meet you half way in the cost.

I'll assume you haven't got the necessary tools to effect the repair (and it isn't difficult - see Lesson 7) so unless you know someone who does leadlighting for a hobby, certain tools will be needed which will add to the cost. I think the first thing to do is get a quote from a leadlight shop (if there is one near you) and then take the quote to the Tender Centre and try to work out a suitable agreement with them.

If you know someone who is into leadlighting that will be a big help, particularly in regard to tools and even if they don't know how to do it, you have the notes from Lesson 7 to guide you both through it.

The cost of the glass to replace the broken panels will only be a couple of dollars at the most and I'm thinking it's probably only 2mm glass, but replacing them with 3mm glass is ok. Hopefully the lead isn't damaged or broken, it may be just bent which is easily straightened after removing the broken glass before replacing the new glass. The easy thing about repairing these cabinets and I'm assuming it has bowed doors which means the glass will fit easier from the front of the cabinet after you determine the sizes. Just have a good read of Lesson 7 to familiarize yourself with the procedure.

I'm also assuming the shelf is 6mm glass which may need to be cut to a certain shape and the edges polished so that you don't cut yourself on it. That will be the biggest expense.

Hope this helps and I hope you won't be deterred from having a go at it.

Best regards,


Sheryn on June 05, 2012:

Hi John, what a kind man you are sharing your wealth of knowledge on leadlighting. This is something I have always wanted to do but never got around to it.

I recently bought a crystal (leadlight) cabinet at the Tender Centre and the men broke a shelf when putting it in the car and someone had put something through 3 of the pannels (little rectangular ones) on 1 side which I didn't know until I had paid for it so it is going to be an expensive cabinet when it's fixed (at my expense) so I would like to start and fix them my self if I can.

I have printed your tutorials and have read lesson 1 and it is very well written. I hope I will be able to fix my cabinet myself as I have never done anything like this before.

Thankyou kindly Sheryn (QLD)

John Jackson (author) from Australia on April 27, 2012:

Hi Des,

Thanks for your comment and the entire 8 lessons are free to print out as 8 separate hubs or as many, or whichever lesson you want should you want to. Not being fully computer literate, I'm not totally sure what you mean by 'download.' If you will excuse my ignorance, I'm happy to respond further about that if you wish.


Des on April 27, 2012:

great pages and thanks

is your tute for download?

John Jackson (author) from Australia on February 18, 2011:

Hi LenaG,

Thank you for your kind comments, I'm really not worthy of that title, but the man who taught me is. When he had a glass cutter in his hand it became a magic wand and he could do amazing things with it. I must admit, he taught me well and I modelled my teaching from his methods with some of my own and I'm sure he would approve.

I loved teaching this wonderful craft to others and I hope those who read these pages can benefit something as well.

Again LenaG, thank you for your comment.

LenaG on February 18, 2011:

Beautifully written by a Master Craftsman. It is just so easy to follow, you are a good teacher. And to think that this was a dying art not that long ago. Your generous sharing of knowledge will ensure that your craft and your skills will live on. Thank you.

John Jackson (author) from Australia on February 15, 2011:

Hi Jules, You're too kind,

Just keep at it, the more you do, the better you become!


crownjulesuk on February 15, 2011:

Cheers John, really kind of you to be so detailed. Hope I'll get as good as you one day!

John Jackson (author) from Australia on February 07, 2011:

Hi crownjulesuk,

Thank you for your comment and it is very much appreciated that you enjoyed the content.

To answer your question, you could use brass wire which would be best in a straight line as brass is a very strong metal to bend on curves. If you do use it, remember to add the thickness of the brass wire to your cartoon line or you'll cut the pieces next to it too big! The size of your panel that you mentioned would certainly benefit by reinforcing, but it's probably easier to use zinc in the long run though.

Again thank you for your comment.


crownjulesuk on February 07, 2011:

Thanks for your great articles, they are so detailed and appreciated on the other side of the world! (UK)

I wondered if you could reinforce your own lead came using brass wire? Like inserting it into the channel with the glass..? I've got a mainly squared panel 1.2m x 0.6m But since you don't mention this, perhaps I need to go shopping for zinc came...!

Thanks! Jules

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