Removing silicone

To remove silicone before it is cured you use a putty or other straight bladed knife to remove any of the uncured paste. Then wipe the area clean with isopropyl alcohol to remove any leftover residue.


After it is cured you should first you should remove as much of the silicone as you can with either a knife or a razor.

A solvent can them be used to remove any oily residue or any remaining silicone. It may be necessary to soak the silicone in a solvent overnight to break it down.

A list of solvents in the order of aggressiveness in attacking the silicone:
Paint thinner (mineral spirits)
Toluene
Xylene
Acetone
Methylene chloride.

When using solvents, as with any material, proper safety precautions should be observed. Material Safety Data sheets are available upon request from manufacturers. Similar information for solvents and other chemicals can be obtained from manufacturers.

There also are “Silicone Eaters” on the market now. The chemical composition is unknown, but are less messy and more expensive than some of the other solvents. Use according to instructions.

What is Waxing Up?

I have had the question above asked. It seems appropriate to respond as part of the tips section, as I had made unwarranted assumptions in posting the waxing up recipe.

Waxing up is the process whereby the cut and sometimes partially painted glass pieces are assembled on and stuck to a glass sheet - called a glass easel - before raising it to a window to get the light that it will receive when installed. This allows you to see what the current state of the window is and how it would look when installed. It shows up weak areas, or pieces which are not really compatible. Although it is used mainly by those who do a lot of painting on their glass, it is equally valuable to assess the composition of a leaded or copper foiled piece. It does ensure that you do not get surprises when you have finished a piece.

The wax used is sticky and stiff enough to hold the glass, but not so sticky as to be difficult to get the pieces off the glass or the wax off the pieces of glass being prepared.

Also some users of the glass easel method paint representations of the lead lines on the back side of the supporting glass to ensure the values of the lines are appropriate for the amount of detail for the various areas of the panel.

Nails

Horseshoe nails are normally used to temporarily hold glass and lead in place while assembling the panel. The flat side of the nail goes against the lead. If the final lead is in place, try to put nails where there will be a solder joint. This will hide any "dings" in the lead. If no lead is yet in place, use a piece of scrap lead to protect the glass from chipping and to raise the glass to a common level before placing the nail. When pulling a nail, rock it in the narrow, side-to-side direction in order to prevent bending the tip.

An even more convenient nail is the round German nail which is hardened steel and sharply pointed. This nail can be started with one hand which is handy when your other hand is busy holding everything together. Use a twisting motion to pull the nail.

Lead-Free Solder

Most of the advice around lead free solder is to avoid using it. However, lead-free solder is essential for making jewellery (which may have skin contact) or any project that may be in contact with food.

Lead-free solder does require a hotter iron than lead bearing solders, plus it does not flow easily. This is in spite of its relatively low melting point.  It has a pasty state between solid and liquid that is prone to lumps and spikes. If this is not bad enough, it also does not take patina designed for lead bearing solders well.

Those using rheostats with their soldering irons, should get rid of the rheostat (see tips on soldering irons), as they limit the ability of the iron to recover the soldering temperature. The best iron to use with lead free solders is a temperature controlled iron, like the 100 watt Weller, or even a higher powered one like the Weller 200 watt. You can get tips that run at 800F to replace the standard 700F tips. This helps with the higher temperatures needed for the lead free solder. But you should not be vaporizing the solder as that is what could hurt you.

Consider the effects of the flux that you are using. Experimenting with various kinds (see the flux tips) can lead you to one that works better than the others.

As always, good hygiene and good ventilation are required when soldering. Also you should wash your hands well and frequently, and eat in a separate room.

Flux Core Solder

A tube of multicore electronics solder is used for manual soldering in the electronics industry - the flux is contained in five cores within the solder itself.

Solder often comes pre-mixed with, or is used with, flux, a reducing agent designed to help remove impurities (specifically oxidised metals) from the points of contact to improve the electrical connection. For convenience, solder is often manufactured as a hollow tube and filled with flux. Most cold solder is soft enough to be rolled and packaged as a coil, making for a convenient and compact solder/flux package.

The two principal types of flux are acid flux, used for metal mending, and rosin flux, used in electronics, where the corrosiveness of the vapours that arise when acid flux is heated could damage components. Due to concerns over atmospheric pollution and hazardous waste disposal, the electronics industry has been gradually shifting from rosin flux to water-soluble flux, which can be removed with de-ionised water and detergent, instead of hydrocarbon solvents.

Waxing up Recipe

Beeswax alone isn't good for waxing up glass pieces on a glass easel, but combining it with Venice Turpentine makes a secure fixing material.

Recipe
250gm block of beeswax
2 teaspoons of Venice Turpentine

Method
Bring the two elements just to a simmer, stir it well and cool.

This produces a tacky material that when warmed in the hand sticks to the glass and the easel. When it cools it sticks firmly.

Use a palette knife to loosen the wax from the easel.

Glass Painting Tools

The tools needed for glass painting are few and relatively common, although the blender is specialised. The minimum you need are:

Glass palette –
A slightly etched glass sheet on which to grind and mix the paints

Palette knife –
A paint knife with a flexible metal blade used to mix and pile the paint

Tracing brush –
A thin and long-haired brush used to apply paint to glass. Sable is considered superior, as it can hold a lot of paint allowing long lines.

Badger blender –
A wide and flat brush made of badger hair used to blend or evenly disperse a layer of paint on the glass, or to stipple a fine layer for a pin-hole effect

Stippler –
A round, thick brush used to apply wet paint and create a stippled matt

Media for Glass Enamels and Paints

Mixing agents
These are the carriers that give "tooth" to the paints and are water-based or oil-based.

Common water-based media are:
· water & gum arabic,
· wine,
· sugar water,
· vinegar

Common oil-based media are:
· clove oil,
· lavender oil,
· damar varnish

Gum arabic
This natural gum (also called gum acacia) is a substance that is taken from two sub-Saharan species of the acacia tree, Acacia senegal and Acacia seyal. It is used primarily in the food industry as a stabliser, but has had more varied uses in the past, including viscosity control in inks. For artists it is the traditional binder used in watercolour paint. It is sold in powder and liquid forms.

Dammar gum
This is obtained from the Dipterocarpaceae family of trees in India and East Asia, principally those of the genera Shorea, Balanocarpus, or Hopea. Most dammar gum is produced by tapping trees, however some is collected in fossilised form from the ground. The gum varies in colour from clear to pale yellow, while the fossilised form is grey-brown. It is used in foods, as a glazing agent, and in the making of incense, varnishing and in other processes. Dammar was first introduced as a picture varnish in 1826 and is commonly referred to as Damar varnish.

Lead Came

Lead came is often just called came. There are two basic types of lead: hard lead and soft lead.

Soft lead is 100% pure lead with nothing added. Soft lead strips need to be straightened in order to remove the propensity to stretch and sag. The advantage of soft lead is being easier to bend and shape to curves and that straightening removes any kinks in the length. Within 50 years it will need to be replaced.

Hard lead has antimony added which stiffens the lead. This results in a stronger finished panel. However this kind of lead deteriorates relatively rapidly. The advantage of hard lead is the added strength and not having to stretch it. It will need to be straightened just before use though. It is still malleable enough to conform to most curves.

Came is available in many shapes, although H, U and C are the most common. The lengths are usually about 2 meters (6 feet). C and U shaped lead is used on the outside of a panel. H shaped lead can be used on both the interior and edge of a panel.

The came’s top and bottom are the flanges and the width of the flange is the nominal size of the lead. These flanges can be flat (parallel surfaces) or rounded (a slight dome on each of the flanges). The central part of the came is called the heart, normally 1.2mm (1/16”) thick.

Common Solder Compositions for Stained Glass

Common solders for stained glass are mixtures of tin and lead, respectively:

• 63/37: melts at 183°C (362°F)
• 60/40: melts between 183°C (362°F) and 188°C (376°F)
• 50/50: melts between 183°C (362°F) and 212°C (421°F)
• 40/60: melts between 183°C (362°F) and 234°C (454°F)
• lead-free solder (useful in jewellery, eating containers, and other environmental uses): melts between 118°C (245°F) and 220°C (428°F), depending on composition.

The 63/37 and 60/40 solders are most often used in copper foil work because of their smaller melting range. This allows the solder to set more quickly than the solders with higher lead content. They tend to give smoother beads also.

50/50 and 40/60 solders are more often used in leaded panel work. Their wider range of melting temperatures allows the solder to spread and become flat.

Soldering Copper Foil

Tip sizeSoldering copper foil is ideally done with a smaller tip than for leaded glass. A 3/16" long taper tip is useful. Use the tip on edge rather than the flat side in order to minimize the iron's contact with the glass. Thus, the iron is held almost vertical. Foil heats up very fast and too much heat can crack the glass so the narrower the iron contact is the lower the risk.

Solder applicationThe solder is applied in one of two ways. The quickest method is to feed solder in on the thicker part of the shiny tip and let it flow down to the foil. The iron is held firmly against the foil and pulled along the foil (which has been fluxed) at the proper rate with the solder being fed at the correct rate in order to produce a slightly rounded, shiny solder bead. Don't try and "float" the iron on top of the solder, be firmly down against the foil. This requires practice to match the speed of movement and the amount of solder fed to the iron.

Alternatively, you can do the Bunny-Hop method. This is easier to control and is done by soldering one tip-length, lifting the iron and soldering the next tip-length, barely re-heating the section just soldered. A variation on this is to place blobs of solder at regular intervals along the foiled and fluxed joint and then move the iron along the joint melting the blobs as you go. This avoids the tide marks at the cooling ends of the solder bead.

Painting Tracing Lines on Glass

Testing the thickness of the paint
Using your smaller brush, load the paint into it, and practice applying black lines on a clear piece of scrap glass. If the paint seems too thick, add a very small amount of water.

Paint that does not stick
If the paint seems to bubble up or not adhere to portions of the glass, it is likely the glass is not clean. You can wash the glass, or simply add a little more water to the paint already on the glass and rub the paint over the glass with your finger or a small piece of paper towel. This will remove any dirt or film of oils on the glass.

Testing the amount of gum arabic
Allow your painted lines to completely dry. You will notice the dry paint has a chalky, opaque quality. Test your paint lines by rubbing a finger across a line. If it easily rubs off like powder, you need a bit more gum arabic. If you can't budge it and it seems hard and crusty, you have much too much gum in the mixture. Adjust the mixtures accordingly.

Inspecting the fired glass
When the glass is fired in the kiln, the paint (which is made of ground glass and various ground pigments) fuses with the glass. Too much gum in the mix, and the paint may bubble, sit on the surface, or do a few other ugly and unprofessional tricks to embarrass you. You have no choice but to start over with a new piece of glass. Getting the amount of gum arable right is crucial to the process.

If the lines are not consistent in colour depth, you can trace over them and fire again. This will darken the lines to a consistent level of colour.

Practice
Practice your tracing. This part of the art is like calligraphy - half the battle is learning to use your tool, the tracing brush, in one or two confident strokes. The quality of your trace line tells the world whether you are an amateur or an accomplished artist! You might even decide this is the only glass painting technique you will ever use. And you would be in good company. A good deal of Gothic stained glass relied solely on tracery for its embellishment and to good effect.

Reinforcement Materials and Methods

Variations in Reinforcement Materials and Methods

Be aware that every reinforcement situation is likely to vary. This is even more prevalent today with stained glass being more utilised in conditions which present varied structural situations.

External steel bars
There are many methods employed to provide reinforcement and a variety of mounting procedures. Surface reinforcement is probably best accomplished with flat cold-rolled galvanized steel bars either 3/8" or 1/2" in width by 1/8" thick. Since they are directly affixed to the solder joints of the section they disperse greater reinforcement than with 14 gauge copper tie wires attached to round or square bars which tend to stretch and consequently result in buckling from the sagging of the section.

Steels
Internal flat steel bars incorporated within the heart of the came are also of excellent service, especially in vertical instances. Horizontally they provide lateral reinforcement but likely no vertical resistance to sag.

Saddle bars
These are normally round or square steel bars that span the opening. The panel is inserted into the opening and blocked into place. The saddle bars are placed in the slots prepared in the sides or top and bottom of the opening, and the copper ties already soldered to the panel’s joints are twisted round the bar.

T bars
These are “T” shaped bars attached to the sides of the opening with the leg of the “T” facing outwards, The panel is supported by resting on the horizontal portion of the “T”. It is then fixed into place and cemented. These bars are normally made of alloys that do not corrode easily.

Enamels

In a discussion of art technology, enamel (or vitreous enamel, or porcelain enamel in American English) is the colourful result of fusion of metals carried in powdered glass to a substrate through the process of firing, usually between 750C and 850C. The powder melts and flows to harden as a smooth, durable vitreous coating on metal, glass or ceramic. It is often applied in a paste form and may be transparent or opaque when fired. Vitreous enamel can be applied to most metals.

Vitreous enamel has many excellent properties: it is smooth, hard, chemically resistant, durable, can take on long-lasting, brilliant colours, and cannot burn. Disadvantages are its tendency to crack or shatter when the substrate is stressed or bent.

Low firing enamels formulated for glass are forms of paint designed to fire between 550C and 600C which avoids the distortion of the glass that would occur with enamels designed for metals.

Glass painting Media

Mixing agents
These are the carriers that give "tooth" to the paints and are water-based or oil-based.

Common water-based media are:

• water & gum arabic,
• wine,
• sugar water,
• vinegar

Common oil-based media are:

• clove oil,
• lavender oil,
• damar varnish

Binders

Gum arabic
This natural gum (also called gum acacia) is a substance that is taken from two sub-Sharan species of the acacia tree, Acacia senegal and Acacua seyal. It is used primarily in the food industry as a stabiliser, but has had more varied uses in the past, including viscosity control in inks. For artists it is the traditional binder used in watercolour paint. It is sold in powder and liquid forms.

Dammar gum
This is obtained from the Dipterocarpaceae family of trees in India and East Asia, principally those of the genera Shorea, Balanocarpus, or Hopea. Most dammar gum is produced by tapping trees, however some is collected in fossilised form from the ground. The gum varies in colour from clear to pale yellow, while the fossilised form is grey-brown. It is used in foods, as a glazing agent, in the making of incense, varnishing and in other processes. Dammar was first introduced as a picture varnish in 1826 and is commonly referred to as Damar varnish

Soldering Fluxes

Fluxes fall into 2 categories: rosin based, and so called water-soluble

1. Rosin Fluxes
Rosin based fluxes are made from rosin which is extracted from pine sap. The purified product is known as "Water White Rosin". The active ingredient is an organic acid, abietic acid and may contain homologs such as dehydro abietic acid and leviopmaric acid.

In addition to rosin other activators may be present at different levels to increase the ability to clean and deoxidise. Activators are compounds that decompose at soldering temperatures yielding ammonia or hydrochloric acid in the process. Flux activity is categorised as R (rosin only), RMA (rosin mildly activated) and RA (rosin activated). A low boiling solvent such as isopropanol is used as the vehicle so they are flammable.

Type R containing only rosin is the least active and is recommended for surfaces very clean to start with. It leaves virtually no residue behind. Thus this is the best rosin based flux for copper foil and lead cames.

Type RMA contains a small amount of additional activator to enhance cleaning and deoxidisation leaving only a minimum amount of inert residue behind. A characteristic of RMA fluxes is that the remaining residue be non-corrosive, tack free, and exhibit a high degree of freedom from ionic contamination after cleaning. These fluxes are acceptable, but more difficult to clean. They are not acceptable for conservation work.

Type RA are most active of the rosin fluxes, and leave the most residue, however the residues can be removed with appropriate flux cleaners. The residues are really difficult to remove in decorative glass work circumstances and should not be used.

2. Water Soluble Fluxes
These are called water-soluble, as the residue left after soldering is water soluble, although the flux is not. The so-called water-soluble fluxes are divided into two categories, organic and inorganic, based on composition. 

Organic fluxes are more active than RA rosin, and inorganic are the most active of all. Both of these are the best of all fluxes to use in decorative glass work, as the residues are water soluble making clean-up easier, and they are more effective in wetting and keeping the copper and lead free from oxidisation at soldering temperatures.


See Also:
Flux, an introduction
Fluxes, a description
The Purpose of flux
The action of fluxes

Soldering fluxes

Paints and Stains

Vitreous paint - glass paint which contains finely ground lead or copper filings, ground glass, gum arabic and a medium such as water, oil, wine, vinegar or urine. These are either high-fire blacks and browns or low-fire transparent colours.

Silver stains - silver nitrate and gamboge gum that chemically stain the glass to varying intensities from pale yellow to orange.

Gamboge is a rather transparent dark mustard yellow pigment. Gamboge is most often extracted by tapping from the Garcinia hanburyi tree. The resin is extracted by making spiral incisions in the bark, and by breaking off leaves and shoots and letting the milky yellow resinous gum drip out. The resulting latex is collected in hollow bamboo. After the latex is congealed, the bamboo is broken away and large rods of raw gamboge remain.

Cementing Brushes

Use stiff, but not hard bristle brushes for cementing. Nylon scrubbing brushes have a good stiffness without being too hard. Some natural bristle brushes are very hard and scratch the came excessively. In general, moderately stiff brushes with about 1 1/2" bristles are fine for cementing. As they do not last very long, they should be cheap, but with firmly attached bristle bunches.

Cleaning the brushes is very simple. The action of rubbing the cement under the leads with whiting causes a natural cleaning action to take place. As the bristles flex back and forward over the came, the cement is forced upward toward the handle, and then outward between the bristle bunches. Only a little effort is required to finish the cleaning: push a rounded stick between the bunches to move out the remaining cement. You now have a clean brush for the next job.

The alternative is keeping the brush in water, but this presents the problem of getting rid of the water (oil and water do not mix) before beginning to cement. As the water will emulsify with the linseed oil, it will be carried into the putty, leaving gaps in the cement when the water eventually evaporates. The cement will eventually harden, even though in water, as linseed oil cures by creating an organic polymer through oxidisation. It can also rot the wood handles.

Keeping the brush in mineral spirits does keep the brush flexible but requires drying/evaporating the spirit before beginning the cementing to avoid the residue of the spirit creating cement that is too thin at the start. This can be a really messy problem!

If you choose the “dry” method, it is important to keep the brushes free of hardened cement as it will scratch the leads badly, if not the glass also. Most brushes will only last 5-10 uses, and as they are not expensive, should be easy to throw away.