Never refuse to refuse?

“Never refuse to refuse” is a statement often seen on social media. 

I object.

If the saying were changed to “never refuse to re-use” maybe I would agree under certain circumstances.

Before you even begin to think about using the broken or disappointing glass, you need to determine what went wrong.  The difficulty may prevent you using it in certain ways, or even at all. 

You need to determine if the break is due to incompatibility.  If it is, you cannot refuse or reuse it in any way.  It will continue to break anything you combine it with.  It must be junked. This means you need to have a way to diagnose the cause to the stress that lead to the break.

If you are certain the break is from thermal shock or inadequate annealing, it is possible to combine the pieces with other glass.

It is essential to determine why the problem occurred to know whether you can re-fuse.  You also need to know, or discover, how to prevent the break for the future. Once the cause of the difficulty has been determined, it may be possible to fuse again, but consider what the appearance will be.  The nature of the difficulty will give you clues to re-usability.

A repaired piece most often shows it is repaired. To try to appropriate the Japanese art of repairing the revered but broken object, just does not work for a broken new piece.  It was a new piece, with no history of use or display.

The phrase “never refuse to refuse” – while catchy – is extremely misleading and can lead to a lot of difficulty. Learn the lessons and move on to make a whole new and sound piece, rather than a repaired piece. 

Fusing slumped pieces together

I have a plate I made using this mold. It’s 6”x6”. … [it is broken into] 8 large pieces. Is it possible to piece it together into the mold and full fuse the plate again in the mold? … Or do I need to try to piece it together on the shelf paper and full fuse and hope for the best?

Full fusing in the mould is unlikely to be satisfactory.  The glass at full fuse will move toward the bottom of the mould, making a thick puddle. Alternatively, it will form a large thick bubble at the bottom, as I see no vent holes in the corners at the base of the mould.  It will also have significant marking from dragging along the mould and from the mould texture.  It also presents some risks to shorten the life of the mould.

Fusing a dropped and broken piece that has been slumped is unlikely to be successful, whether fused in the mould or fused flat first.

Renewing the Grinder Bit

When to replace the grinding head?

An obvious time is when the grinding becomes much slower than previously.  Adjusting the bit up or down to expose a new diamond grinding surface is the obvious first step.  When there is no more adjustment available it is time to replace the whole bit.

Another time to replace the bit is when a bare spot appears.  

One style of wear on these bits is not just the general, even wear all the way around the bit, but where all the diamonds are lost, and the metal is exposed.   

This bare spot can be observed upon inspection.  But most of us do not regularly inspect the bit before turning the grinder on.  There is another way to tell something is amiss.  What you may notice is an unexpected vibration during grinding.  When you experience this vibration, it is time to inspect the bit.  You will most likely find a patch of bare metal.

You do not have to throw the bit out.  If there is space above or below the bare spot that will provide a grinding surface for the thickness of glass you are grinding, you can do something to extend the life of the bit.

Simply raise or lower the bit until the bare spot is below the surface of the grinder grid, or in the case of this illustration, raise it sufficiently high to be above the thickness of the glass you are grinding.

Why do the bare spots appear?

It may be due to manufacture. The bonding of the diamonds may not have been completely even.  But it can also be due to grinding while there is little water – when a paste appears.  This leads to heating of the grinding bit as much or more than the glass.  A hot grinding head, especially those which are resin bonded, can lead to loss of diamonds either in one spot or generally around the bit.

Soldering old lead

This is normally only a requirement when repairing old windows. Usually either to join new lead to the old, or to repair breaks at the original solder joint.

You will need to clean the lead down to the bright metal at the joints. This is more than a rub with steel wool. You need a glazing nail to scratch through the oxidisation layer, the corner of your lead knife, or in cases of mild oxidisation, a brass wire brush might do. But not a steel one as that may scratch the glass and any painting.  

Do not clean the oxidisation off the lead elsewhere. That is a protective layer already formed which leads to the longevity of the came. It is best to leave oxidised lead alone rather than expose the metal to further oxidisation.

Getting to the bright metal where you want to solder the joint means the flux can act appropriately and help the solder form a secure joint.  Otherwise only a weak, cold joint is possible.

Note that you always need to use dust masks or other breathing protection.  You need to have the work area well ventilated and need to do a damp wipe down of surfaces to reduce the amount of lead oxide in the work space.

Repairs to a Vermiculite Mould

Occasionally, during the demoulding of a form, the mould will break.  Not all is lost.  It can be repaired. 

In this example, the mould is not yet fully cured and is damp.  But this can be applied to fully cured and dried moulds too. Notes will be included where the practice varies for the dried mould.

The first stage is to make up a paste of the ciment fondue for the edge to edge repair.  This should be the consistency of pancake batter or slightly wetter.  The mixed cement is shown at the top of the picture in a small plastic tub.

Wet the edges of the mould pieces thoroughly.  This is to prevent the mould from sucking too much water from the cement, which would give a weak adhesion.  On dried moulds, you may have to do this several times to thoroughly wet the mould and the broken piece.

Then begin applying the wet cement thinly to all the edges.  Do not put it on thickly, as you want the pieces to fit back together smoothly. 

Place the pieces together with gentle pressure. 

Then begin to smooth the wet ciment fondue into the cracks between the broken pieces and the main body.  Be careful to smooth the ciment fondu immediately, as it is very difficult to change once cured.

Continue to work the ciment fondue into any cracks that appear as the mould is wetted.

Make sure the cement is smoothed into the cracks so there are no proud areas above or around the cracks.

This photo shows the smoothed ciment fondu on the interior.

Continue smoothing the cement into the cracks at the edges.

Fill the cracks from the outside also

When the application of the cement is completed, make up a mixture of 1:4 ciment fondue to vermiculite. 

The purpose of this is to strengthen the mould in the weak area.  It is not wise to rely entirely on the strength of the edge bonding of the ciment fondue.

You will need to estimate the total volume required, but it is better to mix too much rather than too little.  Make this mix a little wetter than for the original mould.  Water should not be standing in the mix, but you will be able to squeeze water from the ball of mix easily. 

This is especially important for moulds which have already been cured.  You should also put water on the surface that you are going to back up.

It is important to put a water proof material on the workbench to avoid the mould sticking to the bench, or water dripping over other things.

Having wetted the mould exterior again, begin applying the mix to the outside of the mould.

Continue building up the mixture in thin layers.  This allows the best adhesion of the material to the mould and to each layer.  It is easier to compact a small amount of material than a large amount all at one time.

In this photo, you see some of the water being forced out of the mixture by the compaction of the mix onto the mould.

Continue building around the broken area until you have applied sufficient material to the mould to strengthen it.

When you have finished, one area of the mould may be a little larger than the rest.  This is not a problem in its use, as it does not thermal shock, and it does not keep one part of the glass hotter than the glass touching the rest of the mould.

You can now loosely wrap the water proof material around the mould.  Do not seal it completely.  Place the mould in a plastic bag to cure for a day or more, just as for the original mould.

You can then unwrap the mould and fire it to cure it just as the original. The method for curing vermiculite moulds is given here.

Flattening a Bubble

Sometimes a large shallow bubble appears from under the glass.  If it has not thinned there are some things you can do. 

First – do not drill holes.

One flattening method is to place the piece on 1mm to 3mm fibre paper and fire to a slump temperature.  The fibre paper of these thicknesses will allow air out from under the glass.  With sufficient time, the bubble will flatten.  It will take some time as the weight of the bubble is slight.

Another method is to fire upside down.  It does not matter whether the bubble is central or not. This will likely take less time than the first method, but requires an additional firing.  To use this method, place the glass upside down on the shelf with an appropriate separator underneath.  Take slowly to around 620C maximum for as long as it takes to flatten. A low slumping temperature will reduce any marking that later needs to be fire polished away.

When flat and cool, clean and fire polish.

If the bubble has become large and thin, this proposed process will not work. My suggestion for these is to avoid the effort to do an unsatisfactory repair.  Instead use it for one of the many inventive process that use unsuccessful projects.

Charges for Repairs

Repairs always cost more than the owner or artist expects on initial inspection.  The cost is very similar to, or more expensive than, the cost of a new panel if the whole has to be taken apart and renewed.

If it is a repair to part of the window or object, you need to be careful that you do not under price.  The cost elements you need to consider are these at minimum:

• Glass
• Materials
• Time
• Overheads
• Travel
• Installation
• Contingencies
• Profit

Glass - and the cost of obtaining it.  Can you obtain the same or very similar glass to the original?  If you can’t, is the client willing to have the repair in different glass?  If you get approval, you need to cost it – whether you already have it or not.  If you do not have it in your stocks, you need to add in the cost of getting it whether that is travel or postal order.  You need to include the time either or both methods involve in the costs.

Materials – The materials you will use in addition to the glass need to be considered.  These include solder, Foil or lead, flux, patina, cleaning materials, etc.

Time - labour and admin. You need to assess how much time it will take to do the repairs.  Then multiply that by your labour rate. You do have one, don’t you?  If not, get down to it and create one. Use steps one and two of this description.   You also need to take into consideration the time to recreate a pattern for the broken area if extensive.

Overheads – If your overheads are not included in your hourly rate, this is the time to include them in the pricing.

Travel = Your mileage rate + time to get there and back.  If you don’t have a mileage rate, look at what your local authority allows.  This will be lower than what businesses allow, but are reasonable, and publicly available.  (At the time of writing the allowance in Scotland is approximately £0.50 per mile.)  It takes time to get to the location, so this needs to be included in the cost too. Of course, if they are willing to bring the item, it reduces the cost to the client.

Installation – If you are expected to install the piece, you need to include travel (there and back at least twice) and time.  You also need to include the estimated time to remove and install a substitute (and its cost) as well as installation of the repaired piece.

Contingencies - All repairs have uncertainties.  You do not always know what the progress of repairing will reveal.  You can agree with the client that any work required in addition to the initial agreement will be notified for the client to decide whether to proceed or not.  However, you can take on the risk. This is what the contingency is for. You need to build allowance for these unforeseen developments.  A 10% to 20% of the total costs addition to the price is sensible if you are taking the risk.

These seven elements added together give you the cost of doing the repairs.  That is the bottom line.  But there is one more element to consider:

Profit – You do expect to get a profit from all this work, don’t you?  If not, why do the repair at all?  You are not a charity.  Of course, you can decide to give away your profit.  Before you do, think about what you have to pay for repairs – to your car, your plumbing, etc.  You deserve some profit on everything you have invested in this craft that you love.  The love will die without profit.

The profit level will depend on your objectives, but will range from 20% (very low) to 100% (what shops charge). If you put your work in a gallery or shop on a sale or return basis, you expect to have to pay at least 30% on the sale.  That should be the minimum basis of your profit level on any repair.



This may all sound like it is too much trouble for a simple repair.  Yes, it does take a bit of consideration to start with.  But once you have established the basic labour, travel, overhead and profit levels, the rest is pretty straight forward.  You will have an idea of how long it takes to do the work, to travel, the glass costs, etc., and the profit level. You only need to multiply by the rates you have established to give you the price.  I should warn you - it will be much higher than you initially thought.

Repair of a Plastic Barrel Cutter

Generally, there are two parts that can break or be damaged – the wheel and the barrel.

Wheel

If the wheel is damaged or worn, you can replace the head. When considering that, look at the cost of the head and consider whether the small cost difference indicates you should buy a new cutter instead.

The most common damage is a flat spot on the wheel. You can check for this, immediately after dropping the cutter, by lightly moving the cutter across a smooth piece of glass. If you hear a regular ticking sound, the wheel is probably “flat spotted” and will need to be replaced.

A worn wheel is more difficult to detect and is also much less likely to occur. I have been using some of my cutters for 15 years without any sign of being worn.

Plastic barrel

Sometimes the plastic barrel cracks or breaks. This will mean that the oil in the cutter will leak out. So you can consider continuing to use the cutter without oil, or by dipping the head in an oil soaked bit of cotton wool or similar material before each cut.

If the break is at the threaded end and you want to continue to use the ball at the end for tapping purposes, you can glue the barrel back together with an epoxy resin. Make sure the pieces are free from oil. Then glue and allow to cure. After curing, sand down any excess resin to make the cutter comfortable to handle.

Then for additional strength you can wrap with dental floss or extremely fine wire. Start below the glued area and go to the end of the break and back again. You could coat this wrapping with epoxy again both to secure the wrapping and to further increase the strength.

Another solution is to cut the cracked end off and re-thread the remainder. It makes the cutter a little shorter, but will continue to hold oil and give good service.

Or, you could buy another cutter.

Old Cement

Removing Old Cement from Glass

Composition of old cement

Old cement can have a variety of components. One is red lead, another is portland cement. Both create different problems, but both require that all removal of old cement should be done with breathing protection.

Mechanical removal

Removal of old cement can be attempted first with mechanical means. Stand the glass on edge and use a lead knife almost parallel to the surface of the glass to knock off the old cement. This works most of the time. But if the bond is too strong and begins to cause chipping of the glass, you need to switch to another method.

First consider whether the whole panel needs to be re-leaded. It may be that only portions require re-leading and so the remainder should be left in its original leads. This is especially true where there is painted glass, as you do not want to loose the original painting.

Chemical removal

If mechanical removal is not working you need to consider chemicals.

Lye will dissolve linseed oil but perhaps also the paint and so should be used locally only and with extreme care and caution. Testing on unobtrusive areas is required.

Another way to soften the linseed oil is with heat and for this a steam generator works particularly well turning hard putty into the consistency of soft cheese which can be scraped off.

If it actually is Portland cement creating the bond then hydrochloric acid is what bricklayers use to dissolve and remove mortar stains from brickwork. Carefully paint it on the old cement and it should start fizzing and dissolving straight away.

Precautions

What ever you decide to do, test first with some of the glass that will be discarded and confine your chemicals to the cement only and don’t spread them over the entire piece of glass. Wear a respirator at all times during the removal process.

Fixing a Bubble

It is often recommended that large bubbles can be fixed by drilling out the hole if the raised part is thick, or by breaking the thin skin of the bubble and filling with a piece of glass or frit.

My experience leads me to say that "drilling and filling" is hardly ever successful. There always is a mark where the fill has been made, often there is a colour variation too.

There is another possible solution for small bubbles which are at the surface but not yet burst.

Turn the whole piece over and take to just below full fuse. This will allow the bubble to begin moving to the "bottom" of the final piece. Then flip over, clean really well and take to a fire polish - quickly up from bubble squeeze temperature and with no soak - to give a smooth surface, but not allowing it to get so hot the bubble comes back to the top. This will require observation to stop the temperature rise as soon as the surface is shiny.

Small burst bubbles

Small burst bubbles can be fixed by placing small “beads” of glass made from frit in the kiln. The appropriate sized bead can be placed in the hole and others arranged in a pleasant arrangement and all taken to a tack fuse. The beads are made by cutting small squares of glass 5-6 mm and taking them to full fuse. The glass will round up at the fusing temperature and give a number of completely rounded spheres with a flat bottom.

Prevention

Of course, the prevention of bubbles by inserting a bubble squeeze is the best solution.

House Paint on Glass

Windows that have been painted several times over the years often have paint drops or smears on the glass. There are at least two ways of getting it off the glass.
Mechanical means are possible and should be the first trial on unpainted glass. Use a flexible, sharp blade to scrape at the paint. Often there was enough dirt on the glass that the paint will pop off easily. Where you have painted glass – that is glass paint rather than house paint - you need to test how secure the glass paint is. Find an area where any loss of paint will not be noticed and try the mechanical method. If the glass paint does come off, you need to go to a glass conservator who will have a range of chemicals suitable.

The most common chemical removal method is to use an alkaline paint remover. Glass is also an alkaline material, so the paint remover does not affect the glass. Any commercial paint and varnish remover can be used.

Put on a fume mask and rubber gloves. Apply the chemical with a brush and let it work for a while. Agitate the chemical after this pause to see if the paint has been removed. If not, add some more chemical and wait. When the paint has been loosened, rinse with lots of water.

This should not be used on areas with glass paint due to the risk of removing the glass paint.

Ceramic Mould Repairs

Most moulds have a long but limited life due to cracks appearing and accidents. However the life of moulds can be extended with repairs. Most moulds can be repaired, unless shattered.

Cracks can often simply be ignored. If the glass is not getting marked by the crack, then you can keep using it until it widens or goes completely across the mould. If you feel the need to protect the mould before it completely fails, you can add a layer of cement on the back of the mould to support it.

The cement can be a high temperature product like “Sairset” or any other high temperature ceramic cement. The one I like is cement fondu. It comes as a powder – often from sculptural suppliers – which you mix with water to a paste. Wet the mould well to ensure it does not pull the water out of the cement, causing it to fail. Then apply the cement liberally to the back of the mould over the crack.

If you feel the need, you can fill the crack from the front also. Again insure the mould is wet and then press the cement into the crack. Wipe the excess cement off immediately or it will stick leaving blemishes on the mould. Use a wet cloth to do this. You can smooth the filler by using a wet finger to run along the filled crack. These notes apply to which ever kind of cement you use.

Divots or little chips from the surface of the mould can be ignored, if there is no effect on the glass at your operating temperatures. If they need to be filled, you can use a temporary patch by making a paste of batt/kiln wash and smoothing it over the divot. This will last a couple of firings probably. A more permanent repair is to use cements. Prepare as above and smooth into the depression. When cured, particular attention will need to be paid to getting a good coating of batt wash, because the cement surface will reject the water carrying the powder more than the ceramic surface does.



If the mould has broken you will need to stick it all back together. Do not attempt to smooth the edges, they are needed to make as close a match as possible to each other. The rough edges provide a key to location as well. Soak the mould pieces very well. Prepare the cement and apply a little to one edge of the matching pieces. Press together firmly and then apply a backing of the cement as for a crack. Clean off the face of the mould with a wet sponge or cloth until it is smooth and level with the working surface of the mould. Bind this as tightly as the shape permits and leave for several days.

Curing requirements

When using refractory cements, it is best if you can give it a wet cure for a day. This is often easiest to achieve by putting the cemented mould in a plastic bag. After the one day wet cure, it needs to dry for several days. Finally, it needs to have a permanent cure by firing to a temperature of about 25C above the operating temperature for the mould.

Bulging lead panels

There is probably no means by which leaded glass, because of the innate character of lead as its skeleton, can resist its propensity to bend, bulge and sag. Evidence of these occurrences does not necessarily foretell disaster or immediate collapse. Bulging does not necessarily indicate the need for action or re-leading.

There are three basic stages through which stained glass passes on the way to requiring repair;
1. Bulging, bending and sagging
2. Loss of putty and breaking of solder joints
3. Unhousing of the glass from the lead


The points at which solder joints break depends on the materials used.

Since lead, compared with solder, is a resilient material abutting the more resistant solder, breaks will occur most frequently at the junction of the solder with the lead.

With zinc, the situation is reversed. The zinc is of greater resistance than the solder. As a result the break most often occurs on the solder at the point of the zinc junctions.

It is the very existence of resilience in lead which responds to the expansion and contraction of glass that permits the more healthy survival of the glass over the less sympathetic accommodations of either zinc or copper foil. Leaded glass, unlike any other medium, has the unique capability of having its skeleton (lead) replaced, when the need arises, without damaging its body (glass).

Copper Foil Repairs

Repair or not

First consider whether any repairs should be carried out at all. Repairing can sometimes cause more damage, and if it is an older piece, finding an exact match may be impossible. So gluing may be the better approach.
If small shards of glass are missing, daylight is visible through the broken part, or sharp bits are exposed, then it should be repaired, assuming the client is willing to pay.

Starting the repair

Having decided to repair, the first action is to use fine steel wool to remove any patina from the solder around the broken pieces, on both sides.

Removing the broken glass

Next, work out the shards using a fine blade to get between the broken pieces. You should be wearing safety glasses during all the processes of getting the glass out of the piece.

In some cases in may be necessary to score the remaining part of the broken piece with your cutter in a criss-cross pattern, from edge to edge. Also try to go toward the centre of the piece from each corner while making the score lines.

Now start tapping the centre of the broken, scored piece of glass with the ball on the end of your cutter and then work out to the edges. Keep tapping the glass and it should start to fall out. When most of the glass in the middle has fallen out, take out small pliers and gently wiggle the broken shards out, one at a time. Remove all the glass possible, but you might not be able to get the glass in a tight corner.

Removing the solder and foil

Now take your soldering iron and melt off the bulk of the solder seam, slowly going all the way around the hole. Wipe excess solder off on your iron stand sponge. Do the same on the other side. During this process you will be able to remove any remaining small pieces of glass.

Apply the hot iron to the corner joint to expose the piece of copper foil that was wrapped around the broken piece of glass. With a pair of tweezers, grasp and very gently tug out that inner piece of foil while keeping the iron on the solder line to keep the solder molten. Try not to pull the foil off adjoining pieces. If some other foil does come off, then remove that entire length, scrape clean, wash off, dry, and re-apply a piece of the same type of copper foil, cut to size.

Re-flux the exposed foil lines, remove any solder blobs - particularly in any corners - with your iron, wiping excess off on your sponge again.

Replacing the glass

Taking the shape
Take your piece of glass that best matches the broken piece, and position it underneath the hole. Trace the shape of the hole onto the glass. This works best for flat panels. Curved forms usually need to have a paper template made by tracing from the back onto the paper. Cut the shape out of the paper and put it on the piece of new glass. Make sure that the grain of the new glass is in line with the original. Cut the piece out, grind to shape, doing lots of test-fitting in the hole, until it fits.

Foil
Clean any flux off the new piece from your test fittings, and apply the same size and colour backing of copper foil that was used on the piece that you removed.

Soldering
Fit your replacement piece into its place, making sure that it is level with its surrounding pieces. You might want to tape it into place. Check its position, and if you are happy with it, then tack it twice per side.
Proceed to solder it into place. If your fit wasn't perfect, or the piece is a little rough, fill in any gaps with some 50/50 solder. Let it cool, and then finish off with 60/40 solder. Blend your new solder lines with the quality of the solder lines on the rest of the piece.

Cleaning
Wash off the flux, scrub clean, and patina if required. If copper patina was used on the piece, don't worry when you apply the copper patina. It will not match if the panel is not brand new as copper patina ages much more than black patina. Wash the patina and polish it to blend the piece in.

In Situ Leaded Glass Repairs

Here you are, just beginning leading and some one asks you to repair their leaded glass window. But they don't want you to take the window out of the frame. They want you to do it in situ. There are some general guidelines on how to go about it:

• Gently remove the cement from under the came leaves. You can use most any kind of stiff blade. You don't have to get it all out at once. Just work round the whole piece of glass.
• With a sharp lead knife, cut diagonally into the solder joint until you are almost halfway through.
• With a stiff blade gradually work the leaf of the came upwards. A stiff oyster-type knife (properly called a stopping knife) works really well. Apply the pressure to the leaf of the lead came.  Try to avoid levering against the glass.
  
  
  
• Continue to gently lift the leaves of the came until they stand vertical almost back to the heart. This obviously is much easier on thicker came than thinner. I try to avoid doing any less than 6mm, and that is difficult. It is also more difficult to do with half round came than with flat came.
• With grozing pliers gently lift the solder joints. Be careful of the surrounding glass, so that you don't have to replace more glass.
• If you haven't already now is the time to tape the broken glass together.
• Work out the cement between the came and the glass. This should provide you enough space to work the glass out.
• In some cases the glass won't come out in one - taped together - piece. Now is the time to take a rubbing of the opening so you know exactly where the leaves of the lead came are. It provides a pattern piece.  Smash the glass out. Wear safety glasses and gloves.
• If the glass has come out in one taped piece, use it as a pattern. You can trace round it with a felt tip pen and cut inside the lines. Alternatively, put it under the new glass and cut, using the edges as the cutting lines. You can also make a paper pattern from the glass.
• Insert the replacement glass into the opening. Most likely it will not fit in some places. See if the lead came leaves can be opened a little more. Also mark where the glass is too large. You can groze the glass, or if you are near a grinder, grind off the "high" spot.
• Remove the glass one last time, and spread a film of putty on the outside came leaf.  Use a very little, because you can't get outside to remove the excess.
• Clean the glass and handle it so that no finger prints are left on the outside.
• Now that the glass is in the opening, begin to gently smooth the came leaves toward the glass with your stopping/oyster knife. Start by only gently changing the angle of the leaf. Any large movement of the leaf will greatly deform it and might split it.
• If the solder joints are still standing up, take your stopping knife and gently tap the end of it with a hammer. The stopping knife should be parallel to the glass. Any hard hitting will tear the solder joint from the lead. (If you were doing this on a bench rather than on a vertical window, you could heat the solder joint and re-solder without all the tapping.)
• Push stiff black lead light cement under the leaves of the came from both sides if possible. Clean off excess. Polish with a soft brush.

If there are lots of broken pieces next to each other, repair one at a time, as each piece of glass supports the other. Alternatively, take the whole panel/window out and do it on the bench.

revised 26.4.24