Leadlighting Tutorial Lesson 7: Puttying and how to repair a broken leadlight
This is the messy bit that nobody likes very much. I spread an old blanket over my bench before puttying and polishing to protect things and makes cleaning up easier.
A leadlight is puttied to give it strength and to make it waterproof.
Remove all stearine flux from under the lead joins and glass, then vacuum clean. Any flux left behind can expand in the sun and force its’ way out from underneath the putty before it fully cures. Remove all texta from the glass with Metho.
· Only use a metal glaze putty. It contains a primer for bonding to metal. Leadlight shops can supply this putty which is a lot easier than making your own.
· Never use linseed oil putty, (wood putty) it will not bond.
· Never use a plasticised putty, it remains soft and will not harden.
· Never use kerosene to soften the putty, as it is oil based and will dry out slowly, retarding the curing time.
· Use turps to soften the putty as it dries quickly from the putty.
PREPARING THE PUTTY:
There are two methods of puttying, the easiest and quickest first, which is my preference.
Mix the putty on a 6mm thick square of glass, laminex or metal, but not on wood, as it will dry the putty out. Place more than enough putty for the job onto whatever material you use, you will find it is quite cold and stiff so knead it for a few minutes, which will warm it up a little and soften it as well. Poke a hole in it with your finger, then add turps to thin it down. Be careful not to overmix it. If you thin the putty too much, as a last resort add some casting plaster to thicken it up. It will not keep very long doing this, as it will go rock hard quickly, better to add more putty.
Using a kneading motion, mix the turps into the putty, adding small amounts at a time. Each time the turps is added and mixed into the putty, it will still come away from your hands quite freely. The correct consistency is reached when the putty sticks to your hands, a little like toffee or very wet, sticky play dough. Some people prefer to use surgical gloves to mix the putty but I find your hand tends to sweat so I don’t use them. I reduce the putty with one hand so the other hand is clean and free to add more turps when needed, also to remove as much putty from your 'wet' hand with a putty knife or whatever you may have handy. Washing your hands with a household detergent works fine.
Always putty the face or smooth side of the leadlight first. This is the side that sees the weather, so it needs more putty to protect it; portions of putty are placed all over the leadlight. Using a scrubbing brush that has nylon bristles, known as the ‘wet’ brush, (see photo below) first dip it into some kerosene or turps and shake it dry until the bristles are only just moist. A totally dry brush tends to roll the putty into little balls. Start pushing putty into the leadlight with a backwards and forwards motion across the leads. Try to brush at right angles to all the leads. The object is to completely fill the U area. It’s about now you’re beginning to wonder how will I clean this mess up!
Make sure all the leads are full of putty. If you find an area with no putty when cleaning up, just put some in with your thumb. Check also that the outside lead hasn’t bellied out in places, if it has, simply pull it in so it is straight. This usually only happens where there is a large piece of glass on the outside with a large distance between the internal leads that surround this piece of glass and join to the outside lead. If you support the outside lead in these areas with your free hand it will stop the lead from bellying out.
It is very easy to crack or break glass whilst puttying, particularly long thin pieces. Don’t be too heavy handed. If this happens, keep going and finish the leadlight, the broken piece can be fixed later.
When finished, remove as much excess as you can with the wet brush by brushing along the leads, just be sure to remove as much putty as you can from the brush first. Clean the brush by soaking in kerosene (not turps) for no more than two or three days or the bristles will deteriorate. After puttying the first side and the wet brush is still soaking in the kerosene for three days it is now time to putty the second side and most of the putty on the wet brush should have now softened and drained from the brush, so swirl the brush around a bit to make sure. Take the brush and give it a good shake to remove most of the kerosene and it's now ready for the second side.
Nylon bristle scrubbing brush.
The two fish leadlights go side by side.
The harder and slower method.
You can putty up with your thumb if you like but it will take about 3-4 times, maybe even longer than using a brush. If you do choose to do it this way don’t reduce it down by mixing turps into it, use it straight from the tub after kneading it a bit. The reason for mixing turps into the putty is to be able to brush it in, without turps it would be too stiff to use straight from the tub.
After puttying, using either method and using a picker, run round the edges of the leads removing excess putty and making the putty square. Do this BEFORE dusting off with the casting plaster for the clean up, forgetting this step isn’t serious; it just makes the job a little harder. Make a picker by knocking a 30mm. nail in the end of a dowel, leaving the head proud by 10-15mm. Cut the head off and file smooth, rounding off the edges so as not to scratch the glass. DO NOT USE YOUR LEAD SNIPS.
Sprinkle casting plaster liberally over the leadlight and using another scrubbing brush, the ‘dry’ brush, (you need 2 the same) vigorously scrub to clean the glass and lead. As you scrub the casting plaster, it is also being forced into the putty, which helps the putty to set quicker. I usually run around with the picker again just to make sure there are no little ragged pieces of putty showing on the glass before brushing off excess powder to save for the second side, then vacuum clean. Some people use whiting powder for this job, which is ok but it's more expensive than casting plaster (plaster of paris) that does the same job and you buy it from hardware stores. (Putty MUST be cleaned up while still wet, which is certainly the case for both sides but more so on the textured side. Try not to have any interruptions except emergencies, as it will be very difficult to clean if allowed to set.)
Sometimes interruptions are unavoidable and I had a question from a lady who had this mishap where she was called away for a week. She managed to get most of the putty cleaned up by scraping the glass with a bamboo skewer. In the most severe case I would suggest to liberally flood the leadlight with either kerosene or turps, leave it for a while to soak and soften the putty and then vigorously scrub with the 'wet brush' to get the remainder off. Of course, you will need to follow up with the casting plaster. The best you can do IS the best you can do.
Putty and clean one side, then leave it for at least three days. This gives the putty a chance to harden up a little, reducing the possibility of the putty pumping out, if both sides were done the same day. Total curing time for the putty is from 8 to 12 weeks depending on the seasonal temperatures.
After puttying and cleaning the first side, the puttying and more so the cleaning of the second side can be a little harder because of the textured glass, particularly the glass referred to as sparkle. You may find that not all the putty is removed from this glass after brushing with casting plaster because of the deep texture of sparkle. Immediately after cleaning, it may need a second go at it. Place a very light coloured towel under where the sparkle is and this will highlight the areas needing extra attention with more vigorous scrubbing. If you leave it for too long after the second scrubbing the putty will begin to harden up and by holding the panel vertical, the light from behind it will show you where you can use a pin or needle to remove stubborn putty if need be.
Always putty both sides of a leadlight, its’ life will be severely restricted if you don’t.
A mirror is the only exception – putty on the face side.
STORAGE OF PUTTY:
Keep in an airtight container with a lid; air is the catalyst that sets the putty. (Leadlight shops usually sell putty in a 1kg plastic container.) Whatever putty you have left over, simply put it back in the container, which will be partly pre-mixed for the next job. Then pour a layer of water over it, which stops it skinning over. Don't use turps or kero as this will make the putty soggy. You throw off the water and go again on the next one. The water covering will help to prolong the shelf life of the putty for perhaps a year if you're lucky but don't expect it to last too much longer than this. Remember if you had to add casting plaster to thicken it up, you cannot keep it, so don’t put it back in the container.
After puttying both sides and the final clean, apply the patina with a cotton bud to the soldered joins only. Patina is an acid which reacts with the tin in the solder, turning it a greyish brown. It has an active life of about 20 minutes after being applied. Do not dip the cotton bud into the patina container, as this will contaminate the contents. Use the lid then throw out what is not used. You may need to use a few cotton buds on large leadlights. I have found the best patina's to use are the Novacan ones that are shown below that Amazon sell - they are also available in Australia.
If you don't patina the soldered joins they will always stay shiny, they won't darken even with lead polish. By patinaring the joins the solder changes to a darker colour, without patina, shiny soldered joins only draws unwanted attention to them.
Note: Try to avoid getting the patina on the glass, especially clear glass, which has a soft surface, as patina is acidic and can affect the glaze. Wipe off immediately.
POLISHING THE LEAD:
Neil’s liquid polish is best but ignore directions as it's too messy. There is also a paste or solid 'boot polish' type, but it's not my preference.
The polish will not affect the glass, it will simply wipe off later, providing the job of brushing the powder was done properly to remove all the putty from the glass. Any faint smears of putty will hold the polish. The polish is sedimentary, which collects like mud in the bottom of the bottle, put a few small pieces of lead into the bottle to make it easier to stir up. Pour some into a separate container and paint onto the lead with a soft haired artist brush after the patina has dried. Reason for putting in a separate container is because after you shake it to mix it all up, it forms a lot of froth and bubbles at the top of the bottle and putting a brush into the bottle ends up very messy. One coat is sufficient. When finished, put excess back into the bottle. You can clean this brush by washing in water, or simply let the polish dry to a powder on the brush. I prefer the water.
Obtain a good bristle brush, e.g. a good shoe brush or horse grooming brush. (Not nylon.) When ALMOST dry, brush the lead just like shoes. Don't worry if you haven't let it dry quite long enough, it will just need more brushing. It will appear to go backwards before it come to a shine, just make sure you don't let it dry completely. In the summer it can dry very quickly and if you are polishing a large side-light, you may only get half of it painted before it starts to dry. Buff this half now. If you allow it to completely dry before brushing to a shine, for some reason you never get a good black shine. If available, use a lamb’s wool buffer on a drill in order to obtain that bit extra after brushing with the brush.
Note: If the leadlight contains a glass type known as Glue-Chip, prior to puttying, the textured side must be covered in masking tape. Remove the masking tape after puttying and polishing. There are two reasons for this,
1. The nature of this texture can sometimes make it difficult to completely clean the putty off.
2. When applying polish, it will get into the texture and the only way to remove it is with a glass cleaner like Windex, however this will strip the polish off the lead.
A little tip that was given to me by a reader of these notes is that some stubborn putty stains can be removed from Glue-Chip simply with an eraser - something to remember. Just remember too, the putty is still fairly soft so don't be too heavy handed or the putty may pump out on the smooth side.
After installation and cleaning off any fingerprints, only ever clean the leadlight with a soft dry rag or warm soapy water for the above second reason.
DUTCH GLAZING: (Repairing a broken piece in a leadlight.)
This process of repair can either be done to the panel 'in place' or on the bench. It is just as easy either way, but you'll probably find in place to be easier simply because there is no need to remove the panel to effect the repair. Some repairs that I have made to large church buildings needed scaffolding to reach the panels - even a very large ladder was just too dangerous.
1. First make a clear glass template of the broken piece, only slightly larger than the internal area bounded by the lead. (About .5mm overall.) Do this by placing a square of clear glass over the broken piece, tracing the shape with a fine tipped pen, then cutting it out. If the broken piece is clear glass, you can usually treat the 'template' as the piece to use for the repair. You just have to be careful not to break it or you have to start over. An even more accurate way to make the template is to do step 4 first, then hold the clear glass template firmly against the leadlight on one side, you may need a helper, and trace around the inside shape onto the glass with your fine tipped pen making sure you mark as close to the lead all round as possible. As in the next step, EXCEPT where it says cut new piece on the line, which is for the new piece, this is still for the template and has to be cut almost 1mm larger on one side to make the template slightly larger than the opening. (Remember the tracing for the template will be slightly smaller all round than the shape required.) When you're happy with the template shape, trace around the new piece and cut ON the line. If it is a textured glass, be aware what side you want the texture on before tracing the template.
2. When satisfied with the template shape, trace around template onto new piece to be fitted with a fine marking pen. Cut new piece ON the line. Do not discard template yet in case you break the new piece. On most shapes, fitting the new piece will usually fit better in a certain direction - try to determine beforehand which will be the easiest way it will fit in.
3. Check new shape and 'round' off any points on a grinder if you have one. Next, place the new piece hard up against the inside edge of the lead on an edge or side of the broken piece, so that it fits like a jigsaw puzzle and check that the shape on the other side is NO larger than .5mm over the shape, then make sure the 'top' is NOT overlapping so that it will fit in. Arris all edges on a grinder at 45 degrees. (Takes off sharp edges, which tend to jag on the lead.) For those who have been observant, you'll notice in point 1, I mention to have the template .5mm larger all round - this is then reduced on the piece going in even further to be no larger than .5mm on one side of the shape to enable it to fit in.
4. Remove broken piece by criss-crossing with your cutter and tapping out from the reverse side if possible. Rake out old putty with a sharp, pointed object.
5. If possible, open up the leaves of the leads with a fid. Large leads are easier to open up, if you can't you just have to get the glass the right size.
6. Using a piece of beading, gently tap new piece into position and smooth down the leaves of the leads. Only do this when you are certain it will fit, trying to do it too early can break the glass. The strength in glass lies in edge to edge, so make sure when you are tapping the glass into position you tap from one edge at a very shallow angle. Some shapes will fit easier than others, try to fit it with your fingers before tapping with beading. A grinder is invaluable for this work and you will be going backwards and forwards quite a bit before it finally fits. Just be patient, trying to rush can lead to breaking the new piece before it is in, which will be annoying as you have to start over and it may have taken some time up to this point. This isn't a 5 minute job, from the time I get set up it usually takes about an hour to completion for one piece in an easy repair.
7. When you have the new piece in position, centre it in the leads and putty up with fingers, splaying putty at an angle with your picker to give coverage on the glass. There will be some fragments of putty left on the glass from puttying up with your fingers, which is easily removed with your picker. After applying putty to one side it will be easier if you have a helper to have their hand on the glass on the side you've just puttied, pressing the glass against the leaves of the lead to stop the glass from moving when you putty the other side, which will 'pump' the putty out that you've already put in. Sometimes it may not be possible to have that extra hand to help you, so just make sure you completely fill the area of the channel of the lead and glass on the outside to form an effective waterproof seal. (Gently remove any putty that is forced through to the inside with your picker.) After puttying the repair, the glass will be smeared with putty, using a soft paint brush dust the repair area with casting plaster to remove the smears. Don't be too vigorous with this, you don't want to remove putty where you want it to stay. The casting plaster will help the putty set quicker as well. Do NOT clean the panel for at least a month to let the putty harden up before touching it. If the panel is in a door, ensure that it doesn't slam - fit a door closer for safety.
RESTORING OR REBUILDING OLD LEADLIGHTS:
Nearly all the older leadlights were puttied with wood sash putty, which doesn't bond properly to metal and over time it has shrank and begun to fall out of the leads, making them very loose and rattly. Sometimes these leadlights may have sentimental value or perhaps they are just too nice to just throw away. If you have one like this and you want to restore it - providing the soldered joins haven't started to fret too much, which is cracking at the joins and there are no broken pieces, it can be restored fairly easily. After removing the leadlight and raking out as much of the putty as you can on both sides with the point of your lead knife, (you may need a sharp pointed instrument for narrow areas,) then simply re-putty with the right putty.
But if there is a considerable amount of fretting to the joins making it weak, you might say the leadlight is clinically dead, which may need a re-build depending on the amount of fretting and general condition. This is decision time as to which is the best way to go. You could try re-soldering the fretted joins as an alternative, but the fretting is usually cracked all the way through. Remember also what has been said about the difficulty of soldering old joins in lesson 4, but you could try this before making a decision. If the decision is to re-build, the following may be useful.
By securely taping some cartoon material over the smooth side of the leadlight (should be the outside) and take a rubbing of the leadlight with a small piece of lead before you remove it from the door or frame. When you take a rubbing with a small piece of lead, it transfers the outline of the leads in the leadlight directly to the cartoon material from the lead you are using for the rubbing and the side that you form the rubbing on is the side you assemble on. This will become your cartoon - don't forget to measure the leadlight and draw the finished size on the cartoon before you dismantle the leadlight to retrieve the glass, you want to end up with a re-built leadlight somewhere near the right size to fit. If the outside leads are not damaged too much and falling to pieces, measure the perimeter from the outside leads in both the height and width to give you the finished size after removing the panel. Of course, the same for an oval or the diameter for a circle. If it is an oval and still holding together after removing it from the door, it may be possible to draw a pencil line around it to re-build it to the same shape. To help in re-building an oval panel, nail about 6 small pieces of beading along the long edge for half of the oval, which will give you something firm to assemble into - similar to as you would begin to assemble a rectangular or square panel. By doing it this way you can be assured the oval will fit when you come to re-install it. If there are some high spots, simply trimming with a small plane will ensure the fit. It may be a good idea to first take a photo in case the leadlight collapses. Because you are not cutting glass it's not necessary to ink in the rubbing because it's a guide only, but note the lead sizes on the cartoon so you can make it 'as was' before you dismantle it. Number the cartoon and the glass in the leadlight correspondingly, just as if it was a normal build.
The next thing to do is cut through the leaves of the leads on both sides in as many places as you can with the point of your snips so that you can bend the lead and glass backwards and forwards to pull the leadlight apart, dismantling it. (I find the best places to do this is beside a soldered join.) Try to cut in the same place on the opposite side to make it easier to bend the leadlight to release the glass. Start from the outside and work your way in. Be careful doing this, you don't want any more broken pieces than necessary. If there happens to be a couple of broken pieces you can trace around these to cut new ones as you release them from the old leadlight.
Next you remove any putty remaining on the glass very carefully with your lead knife, by holding the glass vertical and chopping down onto the bench, particularly if there are areas that have putty solidly bonded to the glass. You may need to lay the glass flat on the bench and finish by scraping with your knife. If this is successful there is no need to clean the glass any further than this as it will be cleaned by the casting plaster during puttying. If further measures are necessary you can clean stubborn marks with 'Cerapol', which is a ceramic glass cook-top cleaner, or any other similar cook-top cleaner and you shouldn't need anything further than this.
You then nail beading over the cartoon (if you've decided on using a rubbing) and rebuild it as normal. In most cases you will find the leadlight will shrink a little, depending whether a tradesman did the cutting, or an apprentice did it. If the leadlight is totally falling to pieces as you take it out of the frame or door, the job is going to be that much more difficult, you just have to work through it, but the satisfaction at the end is worth it.
Another way, for a rectangular or square panel, if you don't want to take a rubbing, is after dismantling, place all the glass aside on a board as they were in the leadlight, then thoroughly clean them. Arrange the board nearby and after nailing two pieces of beading on your bench, begin assembly from this corner.
CUTTING OLD LEADLIGHTS DOWN TO A NEW SIZE:
This is where you might want to cut an old panel down you've acquired that's in reasonably good condition to fit an existing widow - and it's not really a job for the feint-hearted, but if you need to here's how.
Firstly determine the new size for the leadlight from the frame you want to put it in, remember you are working backwards here so double check your measurements. The frame could either be wood or aluminium so use the correct measurements for whatever outside lead you will be using for the replacement. Once you've determined what outside lead you will be using, measure where the CUT LINE for the new lead is (see Lesson 2) and with your longest ruler, draw a line on the face side with your cartoon pen where you will eventually cut the glass (but not yet) to put the new outside leads on. Repeat this on all 4 sides - it can also be done on a circle. If it is a traditional design, you'll need to measure so that everything is centred. If it isn't a traditional design, you may be able to just cut it down on 2 sides, which will make it easier.
Next with your ruler, cut the glass on the line you've drawn only along one edge, cutting up to and inside the existing internal leads, on the face side only. Move the leadlight to the edge of the bench so that where you've cut the glass, it's lining up along the bench. Then with one hand holding the leadlight firmly on the bench, start separating each piece as you go along one side of the leadlight with your free hand by bending gently downwards only. It shouldn't be too difficult if you've made a good score line and you won't have to bend it too far before separation begins, so stop bending the moment you see it happen. Repeat these steps on each edge, one at a time.
Now your leadlight is 'cut through' on all edges but still being held together by the leads. Again, whatever lead you want to use, measure in from the line you've drawn on the glass and is now cut, the amount the new lead will be overhanging the glass from the cut line on the glass to where this new lead will butt against the internal leads. Measure a fraction smaller to ensure a close fit when you install the new lead. (Remember when building a new leadlight the first piece fits under the leaves of the outside lead - the same thing is happening here only in reverse.) Then with your ruler, draw this line only on the face side, marking both the glass and the leads so you know where to cut through on the leads. You have to mark the lead on both sides, so when you come to mark the lead on the other side, you can see where to draw the line on the leads directly from the line you've drawn on the glass on the face side to get them identical. When cutting though the leads on both sides, if there are any internal leads that joined the outside lead at an acute angle, the drawn line will give you a reference for cutting parallel and minimising gaps.
Beginning on one side, carefully and gently cut down through all the leads with your lead knife until you feel it touch the glass. You can either cut through the leads on all of one side before turning the panel over to repeat the process or you can complete both sides one edge at a time. The next step is removing the cut down edges one side at a time. Again, move the leadlight to the edge of the bench with the cut glass lined up on the edge and carefully bend the sections to be removed down and up until it comes away from the leadlight. It is now only held by the hearts of the internal leads because you've already cut down to the glass so it won't need a lot of bending before it separates. Your first bend should be downwards as you've already separated the glass and you may find as you bend upwards there may be some splintering to the edges of the glass on the first bend upwards but it won't do any more damage than that - just be gentle as you work through it. As you bend back and forth, gently pulling at the same time the heart is being slightly stretched and it won't take too much effort before it separates.
Now the worry part is over and you only have to solder on the new outside leads and if you've measured and cut the internal leads correctly the new lead will butt nicely up against the internal leads for re soldering. Make sure you prepare the old leads properly by giving the surface a good scrape back to bare metal to make soldering easier. And there you have it!
© 2010 John Jackson