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 500mm.
EG, if the leadlight is 2mtrs high and 500mm wide, as in a side-lite, reinforcing won’t be necessary, but if the leadlight is 2mtrs high and over 500mm 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 1mtr x 250mm) but still be careful of slamming.
The side-lite at the right in the above diagram, being 800mm 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 reqired at least. However suppose you had a panel about half this area, let's say 940 x 450mm, 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.
THE PROCESS OF REINFORCING:
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.
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 1mm and is usually inserted in a twin heart lead called 51H, 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 1mm 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 51H lead, remember there is the thickness of both hearts plus the brass bar totallig 3mm, but you had best allow at least 5mm for the cut line as there is a wider space where the metal goes. The overall width of the 51H is 9.5mm, 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 2mm 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 2mm line for the cut line for these leads, as the hearts of these leads are 2.1mm 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.
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.
THE STACK GLAZING TECHNIQUE:
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 6mm U zinc on the top of the lower panel.
A 13mm H zinc is used on the bottom of the next panel which fits over the 6mm U zinc and hence joins and so on.
Just remember that both the 6mm and the 13mm 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 2mm 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.