Darkening leads

There are several ways to darken the leads in leaded panels. Three are to:

use patina on the leads,

brush with on stove blackening with a soft brush, and

simply brush after cementing.

A certain number of people use black patina to darken the leads after cementing and cleaning the panel.  This certainly gives a black result, but it introduces an acid to the panel. I do not do this, nor do I recommend it.

Another method of darkening is to apply stove blackening or black oil paint to the panel to make the leads dark.  I recommend that you put very small amounts on a soft brush and then brush over the leads.  It might have to have a little more colour added for a large panel, but that is better than having to clean up large areas of smudged black over the glass, especially with painted glass.

credit: PicClick UK

But...

You can darken lead came without patina or black colour.  You finish the panel with the scrubbing brush to push whiting against the fillet of lead light cement against the leads as normal.  This has the effect of cleaning the glass as well as stiffening the cement at the edge of the cames. Remove the excess whiting as normal.

But, before picking out all the excess cement once the scrubbing brush process is finished, use a soft brush, such as a shoe brush, over the whole panel.  This can be mechanised by using a soft bristled mop in a drill motor on a slow to medium speed.  This will pick up colour from the cement and spread it evenly over the lead and solder joints. It will give a dark grey appearance to the whole of the leading and solder joints as well as polish up the glass. 

The degree of shine will be dependent on the amount of time you wish to spend, but can be a polished to a very dark grey to black colour.  This will last longer than simple black colour brushed onto the leads, as it is bound by the linseed oil in the cement to the surface of the leads. Also, it quickly dries so that not so much black is transferred to your hands as you handle it.

Making lead cames black during the finishing of a leaded panel is as simple as brushing over the cames before picking out all the excess lead light cement.

Cementing Leaded Panels, part 3

Polishing Lead Cames

Use a soft brush to polish lead came. Don't pick out the cement until the polishing is done, as it provides the colour for darkening and polishing the lead and solder joints. The action with the polishing brush should be gentle and rapid, much like polishing shoes. If the shine does not come, you can use a very little stove blackening (carbon black mixed with a little oil) If you use a lot, you will have a big clean up job. A little stove blackening spreads a very long way.

realglasspainting.com

Before turning the panel a final time, put down paper or cloth, to avoid scratching the solder joints while polishing the other side. The result should be shiny a black came and solder joints that does not come off the way a final buffing with stove blackening does.

Finally, pick out any remaining cement.

Rest horizontally with weather side down for traditional installations. If the panel is going into a double or secondary glazed unit, you may want to reverse this. The reason for having the smallest exposed cement line on the outside is to allow the water to run off the window with the minimum of area to collect. In a sealed unit or for secondary glazing, you may want to have the smallest amount of cement showing inward for appearances, as there is no weathering reason for the traditional method.

Rest for a day. Pick out the cement again. If the cement was stiff enough, there should be no need to do any more picking at the cement after this.

Polishing Panels with Paint and Enamels on the Glass

Do not use black patina on the lead/solder lines on your finished work if there is any painted glass into the panel whether leaded or foiled. This relates to traditional painting on glass, using vitreous paints, fired at ca. 670C and to cold paints often cured in a domestic oven.

When using enamels within the painting, do not let any patina come in contact with the finished production. The patina will etch out all the enamel colour. The patina will etch off the outer layer, either removing the shiny top layer of paint, or the delicate lines of detail work altogether. Copper patina takes a little of the paint off, but not nearly as badly as the black.

Instead, brush the panel with a natural bristle brush, as used for putty clean up, and polish.

Silver stains that have been properly held at the maturing temp, should withstand any patina application, as they have become incorporated at the molecular level with the glass.

Polishing Brushes

The polishing brush should have moderately soft bristles. A long bristled shoe polishing brush can be used, although one that is a little stiffer does the job more quickly.

A shoe polishing brush

It is important to keep these brushes free of hardened cement, as a brush containing pieces of hardened cement will scratch the leads rather than darken them. As soon as the polishing is finished, inspect the brush for little balls of cement. Rubbing the brush against a clean rough surface will clean it while the cement is “wet”. Also running the brush at an angle on the sharp edge of your work bench will clear some of the cement adhering to the bristles.

A polishing brush with slightly stiffer bristles

If the cement hardens, you can clean the brush by crushing the hard balls of cement with a pair of pliers. Or you can just get a new shoe polishing brush.

Hand Finishing to a Flat Edge.

Hand finishing an edge does not require expensive electrical tools, although they do make the process quicker.  This is a note on how to get good-looking edges without expensive equipment. Only a few materials are required.

• ·         A thick sheet of float glass for the grinding plate
• ·         Aluminium oxide or silicon carbide grit in approximately 80, 180, 400, and 600 grits to act as the abrasive.
• ·         Wet and dry sandpaper of approximately 1200 and 2400 grits
• ·         Paint pens (white and gold work well)
• ·         Paper towels for drying
• ·         Water for rinsing
• ·         Large bucket or basin to collect the rinsing water

The thick flat float glass acts as the grinding plate.  It is flat and smooth, making the grinding and polishing flat. 

If you have a lot of glass to take off to get a straight edge use 60 or 80 grit.  If there is not much to take off, start with 120 or 180 grit.  There is no need to make deep scratches on the edge that will take time to eliminate, if a finer grit will do the job.

Put 80 (or finer) grit aluminium oxide or silicon carbide on the glass grinding plate and make slurry with water. 

Slurry mixed and the circular motions of grinding can  be seen
photo: hisglassworks

Move the edge firmly in circular or figure of eight motion over the grinding plate until flat. If the slurry becomes pasty, add more water as you do not want a thick grinding mix. Maintain the same angle of the glass piece to the grinding plate at all times so you have only one plane of glass to take to a polish.

When the edge is flat, clean and dry the glass, and especially the ground surface to remove all traces of the coarser grit.  Set the piece aside to dry.

While the piece is drying, clean off the grinding plate. Scrape off the slurry into a pot set aside for that grit for further use, or into newspaper or other temporary container and then into a waste bin, not the drains.  It is a heavy material and will block drains. Rinse the plate off in a basin of water to ensure there are no coarse grains on the glass.  The residue will settle to the bottom and you can decant the water off once it clears. These grits are not very expensive so repeated use is not essential, just economical.

The next step is to paint the now dry glass edge with a white paint pen.  This will allow you to see when you are ready for the next step, by the disappearance of the paint from the scratches.  Of course, if you are grinding a white or other pale glass, a gold paint pen will be better to see those scratches.

While the paint is drying, make a slurry of the next finest grit. Then begin grinding. The first element in each grinding stage is to give an arris to the edge of the glass.  This prevents chipping the sharp edges.

 

www pavingxxpert.com

When the white paint is gone from the edge, you can progress to the next grit.

At each stage of grinding you can reduce the grit size by half (double the number). This is the generally accepted reduction of grit size to make the removal of the scratches of the previous grit least time consuming. You can reduce the grit size by more than half if you want. Most often reducing grit by large amounts means more time is spent at each stage.  Experience will show you how much you can reduce the grit sizes beyond the accepted intervals.

Stopping at 600 or 800 grit will enable an edge to be fire polished with ease and minimum heat.

At each stage you need to clean the glass and grinding plate as for the first change of the grit size. This repeated cleaning usually means that the artist either has separate grinding plates for each grit, or the grinding is saved up until there are a few pieces that need the same treatment.

A piece of wet and dry sandpaper fixed to a glass plate

After 800 grit, you may wish to progress to wet and dry sandpaper for the finer polishing, using 1200, 2400 and, if you want. 6000 grit. Fix the paper to a glass plate.  Often, simply folding two edges under the glass will be enough.  Add water and proceed as for loose grit.  Hand finishing to this level will eliminate the need for fire polishing. 

Of course, for smaller areas, you may wish to use diamond hand pads.  The need to use water and rinse between grits still applies.  The diamond hand pads are usually most suitable for short straight edges. The longer ones need the kind of treatment outlined above.

Hand Finishing Jewellery Edges

Often jewellery scale pieces need to have their edges finished before the final wrapping or hanging on the necklace. This is frequently done by running the piece against the grinder, dumping it in water and then cleaning with a tooth brush or similar before the next process.  What is described here can be used on fused and “raw” glass both.

You can finish the edges of pieces by hand. 

Get a flat piece of glass – window glass is good for this.  You can put a fine grit such as 200 onto the glass and wet it to a paste. Place the edge of the jewel on the glass and begin rubbing with moderate pressure in an oval or figure of 8 motion.  You will be surprised at how quickly the edge is refined.  You can follow this up with finer grits.  Make sure you clean the jewel and the grinding plate thoroughly if you use the same glass plate for finer grits.

If you want a less messy - but slightly more expensive - method, use wet and dry sandpapers.  These can be found in grits from 200 to 6000, although you will not need to go beyond 1200 which will give you a smooth, shiny edge. These need to be kept damp too.  If you are planning to fire polish the pieces, you can stop at 400 or 600 grit.

This process avoids the water soak stage, can bring back into use the pieces you forgot to soak, and can be taken all the way to the finished edge.  If you are doing only a few pieces, it is much faster than a fire polish in the kiln.

Rounded edges on slumped pieces

Often people want to know how to get rounded edges during slumping of a single layer piece, especially when trying out techniques with their spare art glass.

Achieving a rounded edge on a slumped piece is a combination of temperature, thickness, larger top layer and cold working.
Rounding of the edges of a piece of glass occurs at tack fusing temperatures, which are beyond the slumping temperature. It is possible to take the glass to a tack fuse within the mould as long as you are prepared for some consequences.

More mould marks are evident on the bottom of the vessel.
Mould life is reduced.  You get a lot more mould marks on the bottom of the glass because the bottom of the glass is softer than in a standard slump. These marks will be directly related to the surface texture of your mould.

You need to re-coat the mould before the next slumping to avoid the kiln wash sticking to the glass.  Ceramic based moulds last a long time if fired below 680C. But numerous firings at tack fusing and higher temperatures increase the possibilities of glass sticking to the mould and occasionally, thermal shock. If you insist on tack fusing in your mould, you need to renew the separator each time, as the kiln wash breaks down at tack fusing temperatures leading to it sticking to the bottom of the next piece you fire in that mould.

You may get an uprising at the bottom, as the glass slowly sinks down the mould and pushes the glass up at the bottom in any mould other than a simple, shallow shape.  

These things indicate that it is best to tack fuse first and then slump at the lower temperature.

Of course the best result can come from using 6 mm of glass, with the top layer 6 mm larger than the bottom layer. This allows the upper layer to sink over the outer edge of the lower one, giving a rounded edge with no sign of any differences between the two layers.

Cold working solution 
If however, you want to work with a single layer, you need to realise that the edge will be the same when it comes out as when it went in. So you need to cold work the edge before slumping. You do not need sophisticated machinery to do this. A few diamond grit hand pads will do the job. Start with one at about 100 grit to shape the edge. Make sure you keep the pad and working surface damp. If you begin to get a white paste appearing, you need more water.

After shaping the edge satisfactorily, take a pad of about half the grit size (twice the number) and begin the smoothing of the scratches created by the shaping. When finished with one grit move on to the next. You can use a paint marker to help tell when one grit is finished. 

This process will give a sheen that will change to shiny during the slumping.
  

  

Encapsulating Glass

Points to note when making panels for encapsulating leaded panels in double glazing units.

In building a new panel, the perimeter should be of “Y” came. This allows the double glazing spacers to be placed on either side of the leg of the “Y”, incorporating it into the structure of the whole unit.

The tolerances for double glazed units are much less than for single glazed wooden units.

If you decide to use mastic, it must not be linseed oil cement, as the oxidisation process produces a condensate that fogs up the interior. Use a butyl putty instead.

It is also possible to finish the panel without any mastic under the leads, as the double glazed unit will provide the structural support. You do need to dress all the flanges of the lead to the glass to avoid light showing around the edges of the glass.

Finishing the leads should be with a polishing brush only to avoid introducing chemicals in a closed atmosphere. The polishing brush will bring up a dark colour on the leads and solder joints with repeated light brushing. This also is an indication that the solder jointing should be as neat as possible with small flat joints.

Pickling

Pickling Silver

This term relates to the removal of firescale from silver by use of chemicals, often slightly warmed.

When heated, silver blackens on the surface. It is common in silversmithing to pickle the object, bringing the shine back.

There are several methods.

Hydrochloric acid is the most common chemical used. It normally is used in concentrations of 10% or less and often is slightly warmed in a soup warmer or other similar temperature controlled container

Hydrogen peroxide (sparex) solutions can be used, but are a bit slower. This also is used in a soup warmer.

Acetic acid, available from most chemists and home-brew suppliers, can be used but is so much slower that significantly long soaks are required.

The best solution for this is a 5% solution of citric acid or similar concentration of tri-sodium citrate.  This latter is best for glass, as it chelates the corrosion or stuck kiln wash, but does not etch the glass even after 48 hours soaking.

Revised 6.1.2022

Patina Application

The application of patina to solder and other metals consists of three stages, cleaning, application, protection.

Clean the solder bead

Both flux residues and contaminants are left after soldering. Cleaning can be a combination of cleaning with abrasives and also with alkaline materials. Baking soda – sodium carbonate – can be used to neutralise any of the acidic flux left. It bubbles in the presence of acid, so gives a visual check on the amount of acid left. Since it is an alkaline substance, it will react with the acid of the patina to weaken the reaction. It is important to rinse the baking soda off with plenty of clean water.

Abrasive cleaning with materials such as steel or copper wool can be used. Some advise against this as metal residues can be left. However the abrasive scrubber used in scrubbing pots can be used to finish the cleaning without leaving metallic residues.

Apply the Patina

As patinas work by chemical reactions, they are specific to various metals. Those designed for solder work by reaction with the tin mainly, those for lead obviously react with lead, and those for zinc react with zinc - while each of these may work with other metals, they work best with the metal they are designed for. Too much rubbing while the patina is wet simply interferes with the action of the acid. Application of enough patina to allow it to "soak" - actually time to react with the metal - is much better than rubbing. To repeat, it is a chemical reaction, not a buffing process.

Once the patina is dry, you can use the baking soda solution again to neutralise the remaining acid on the metal. Rinse well. rub gently with a dry cloth to assist the drying, do not scrub. When dry again you can wax the metal.

Protect the Patina

Some allow the waxed piece to sit for 24 hours and then re-wax it. The applicator should be a soft object such as a cotton bud or soft cloth. Do not polish it until it no longer is showing black. Rather allow it to sit undisturbed for several days. The patina will get darker and smoother over time. Don't worry too much about getting it pitch black, or birght copper the first day.

Hanging Panels – Perimeter Wire

Often it is most secure to have the bottom of the panel supported, rather than relying on attaching hooks or loops to the edges of the panel.Panels with “H” lead came are the easiest and neatest to form a wire around. You can use twisted brass picture wire (which has a steel strand embedded) for this purpose or solid copper wire. When using picture wire, form a loop at one end by twisting the strands. In this example I am using solid copper wire.

Make a loop as described.


Open the leaves of the came at the top and solder the wire with the loop to the heart of the came. Use as little solder as possible and keep it away from the leaves, as solder on the leaves makes folding the leaves back very difficult.

Continue the wire around the side. Pull the wire tight and tack solder the wire at the bottom of the side. Continue the wire around the bottom and do the same at the other side.

Pull the wire tight to the top of the panel. Bend the wire over at the height you wish the loop to appear above the panel. Twist or bend the wire and solder it to the side of the came’s heart.

Close the flanges of the came over the wire and you have a neat finish to the edges.

You can, of course, decide to hang the panel from the wire going around the panel. In this case you eliminate the loop forming at each side of the panel’s top. I solder the wire ends together at the bottom, in addition to soldering the wire to the came at each corner. This provides me with the certainty that the wire will not come loose.

This can also be used to provide the hanging supports when placing the panel in a wooden frame. It takes the strain off the frame but still provides firm support of the panel.

Cleaning Solder Beads

After soldering, cleaning and drying your piece, use fine (000) or extra fine (0000) steel wool and a brass wire brush to go over all the beads. Use the brush first if you want to use it, and follow with the steel wool, since it will provide fewer scratches. This helps remove any leftover flux that on solder lines.

Omitting this step increases the chances of developing whitish blotches later on the solder lines. However, including this step makes a better base for applying the patina, if you are using any. After using the steel wool, use a soft brush to remove any residues from the steel wool, brush, flux or solder.