Cementing Leaded Panels, part 1

Part 1: The Start

Cementing panels is as old as leaded glass - about 1,000 years - so it is a time-proven process using simple materials. The object of cementing is to make a leaded panel weather/water tight and sturdy. It can be messy and dusty, so putting on an apron and a dust mask are a good idea.

Start on the side that is already facing up after soldering. This normally will be the rough side. This way you do not have to move the panel much until it has stiffened with the addition of the cement.

Cover all open bubbles, rough glass (waffle, ice, etc.) and all painted glass with masking tape. Put the tape over all the relevant areas of the panel, then use a sharp knife (X-acto, scalpel) to cut the tape at the edges of the came. The cement will go under the came, but not into the texture of the glass. This will make the clean up of the glass much easier after cementing.

You can purchase commercially made lead light cement or you can make your own.

With the panel on the bench, put a dollop of cement on the glass and rub it in all directions with a stiff, but not hard, bristle brush to force it under the lead. 

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When the cement has been pushed under all the cames, but with a slope of cement showing, spread a little fresh whiting or sawdust on the panel and gently push it against the cement under the leads. This begins the setting process and keeps the spreading cement from sticking hard to the glass or bench.

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Turn the panel over to cement the second side the same way as the first. If the panel is a large one, you may want to use a board to support it in these early turning stages. No gaps can be tolerated in the cementing. Cement leaking out the other side is good evidence that all the gaps between the glass and the came are filled. Again, after cementing, sprinkle new whiting/sawdust over the second cemented side and rub it gently into the exposed cement.

Part 2
Part 3

Reinforcement

Reinforcement is probably the most important design element in stained glass. Without adequate reinforcement, all other effort and results are secondary, because an inadequately reinforced work will not survive, and that is sad.

GuidelinesThere are no all-encompassing reinforcement rules. There are however some basic guidelines:

• Restrict non-reinforced panels to between 2 and 4 perimeter metres (a rectangle of 1 by .5 meters up to a square of 1 meter).
• An abundance of horizontal or vertical lead lines within the leading concept are most likely best served by a vertical reinforcement system.
• A diagonal or bent reinforcement bar dilutes its reinforcement capacity in proportion as it deviates from the straight. Such supports serve to merely stiffen the section.
• Know that most reinforcement systems provide only lateral reinforcement.
• In most architectural situations which adhere to sections of 4 perimeter metres, reinforcement will usually be 12” to 18" apart in vertical accommodations, with an average around 15".
• Placement of reinforcement should be established on the initial scale layout in which the design is to be done. It should not be an addition after the whole is designed. That increases the likelihood that the reinforcement will be an intrusion upon the design.
• Very tall or wide windows should have an armature of some sort. This is commonly "T" bars for the panels to rest upon without transferring their weight to the panel below. Other more complicated armatures can be seen in large windows, such as at Canterbury Cathedral.

With diamond and other quarry lights, reinforcement placement cannot always be equally spaced. In such instances, it is probably best to have the shortest distances between the reinforcement at the base of the section where the weight creates the greatest likelihood of buckling.

Inserting Glass into the Came

If you have consistent difficulty in sliding the glass into the came, you should consider dressing the came before use. Dressing the came consists of running a fid or other hard material along each of the four flanges of the came. In doing this, you are pressing each flange in turn down against the bench or other smooth surface.

Dressing the cames gives a slight bevel or ramp for the glass to slide over the edge of the came and into the channel of the came. You can dress the whole length at once, or as you cut the pieces off from the main length. Dressing shorter pieces is less likely to bend the came.

Of course there is a second stage of dressing the lead came upon completion of the soldering.

Structural Reinforcement

Leaded light panels often require additional support against wind pressure or vibration. Whether this is needed depends on the size and location, e.g. if in a door or a ventilating window that is constantly being opened and shut.  Large leaded glass windows need some bracing against the force of wind and rain. This can be achieved by using one of the following supports:

• Saddle Bar
• Reinforcing Bar (Rebar)
• Steel Core or Steels
• Zinc Section

Saddle Bars are the strongest method of support and are used in large external windows for preventing panels from bowing inwards. They resist wind pressure in exposed situations. Saddle bars form part of the latteral support structure of the window. These bars are attached to the panel with copper or lead ties.  These ties are soldered to solder joints across the narrow width of the panels.  The bars are fixed to the perimeter of the opening either by the mouldings or by being inserted into holes in the frame. The sides of the opening provide the ancor points for the bar.  The panel is fixed to the bar by twisting the ties around it.

A saddle bar fixed in position at the side and the ties being twisted around the bar.

Sometimes the opening is divided by sideways "T" bars.  Generally the leg of the "T" faces outwards and the panel is set onto the ledge formed by the leg of the "T".  This leg often has a series of holes drilled in the leg, for pins to be inserted to hold the panel in place until the sealant has cured.

An example of "T" bars being used on a small side opening window

Rebar is another external support.  It generally is a zinc coated steel strap about 2mm by 10mm and asl long as needed to cross the panel.  This tends to be soldered directly to the panel at the solder joints either on the inside or outside. One advantage of this material is that it can be bent to conform to the lead lines of the panel.  In consequence it is not as stiff as saddle bars are.

Steel core
Steel cores take two forms - either steel-cored lead or steel strips fitted into the lead cames when leading.  The steel cored lead came is less available nowadays.  They are mainly used in domestic glazing where support is required particularly in leaded lights with diamond panes when they are inserted in continuous diagonal leads. The steel cores are not adaptable to significant curves.

Steel cored lead came cut away to show the steel core

Zinc
Zinc section came is often used to frame a panel that is not glazed into a window or frame. It has been used in the past for both straight and curved lines.  Using it for curves requires a came bending machine to give good, regular curves.  It gives a panel strength for ease of handling, but does not resist sagging or bowing at the centre.  The other disadvantage of zinc is that it corrodes much faster than lead.

Image showing a variety of zinc came

Scheduling to Room Temperature

Why Schedule the kiln to room temperature? The kiln will cool slowly enough at the final stages.

How do you know?

Relatively large thick pieces need slow rates of cooling below 370°C.  Complex tack fused pieces require slow cooling rates as well as the long annealing soaks. These required rates of cooling may be slower than your kiln’s unpowered rate of cooling.

This means you need to know the natural cooling rate of your kiln from 370°C down to room temperature to be sure you are cooling at a suitable rate. The method described in this blog post gives you information on how to calculate the natural cooling rate of your kiln.

I program my firings to about twice room temperature. Yes, the kiln does not turn on much during that time,  but when I crack my kiln open to speed the cooling, the switching on of the relay tells me I am cooling faster than programmed, and I can reduce the size of the opening to avoid too rapid cooling of the piece.

The following chart is a way to assist in recording your kiln’s unassisted cooling temperatures against time to give you the natural cooling rate at various temperatures.

Natural Cooling Rate of the Kiln

Kiln Name:					Cooling Rate
observ'n	Time (hr:min)	Temperature	Difference		rate/min	rate/hr
1	:		Time (mins)	Temp.	=temp/mins	.=temp/min*60
2	:
3	:
4	:
5	:
6	:
7	:
8	:
9	:
10	:
11	:
12	:
13	:
14	:
15	:
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17	:
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19	:
20	:

Candle shades

These kinds of drapes are generically known as handkerchief drops, as they form the kind of shape that is formed by holding the cloth in the middle and letting it drape.  They can be done as small drapes over kiln posts, cocktail shakers, and much larger forms.

Two heights of new cocktail shakers

A well used cocktail shaker with kiln wash

A kiln post wrapped in preparation for firing

Two short kiln posts after firing

When preparing several drapes to be fired at one time you need to consider several factors.

Higher in the kiln is hotter.

The heat in a kiln, as in an oven, is greater the higher in the kiln is supported.  This means that taller supports will drape quicker than shorter ones. The consequence is that all the drapes should be of the same height.

A single layer that has begun to stretch at the shoulder of the former 

Larger spans fall quicker than smaller.

The more of the glass that is unsupported, the quicker it will fall, even at the same height. This is because the larger amount of unsupported glass has more mass than a smaller one and so falls quicker.  Plan for all the glass to be of similar sizes.

These two were fired at the same time. The back one is larger than the front 

Different shapes fall in different ways.

Squares and circles are the most common shapes used in a  drape. The corners of squares are points that are further away from the centre of the support than the sides.  These points begin to fall first, drawing the sides in later in the firing.  Circles form a taco shape before the ends of the “taco” begin to fall.  This deformation of the circular “taco” takes longer than a square takes.

Care needs to be taken that the glass does not thin excessively at the shoulder of the support.  There is less difficulty, if the same shapes are fired together as different heat work is required for each shape.

Observation by peeking is required to stop free drops at the right time.

As in all drapes, it is important to observe the progress of the drape at intervals.  This is best done by quick peeks to note the development of the shape and to move to the cooling segment when the drape is complete. This also requires a scheduling of a long soak and knowledge of how to advance the kiln controller to the next segment of the schedule.

Kiln Maintenance

Switch off the kiln before doing any maintenance.

Before or after each use

Vacuum the inside of the kiln. Use a low suction setting, especially on fibre walls and ceilings. Stronger suction is possible when cleaning a brick floor.

Example of vacuuming around elements

Example of vacuuming lid without elements

An alternative to vacuuming the elements is to use the air compressor hose at low power to gently blow out any dust settled in the element grooves.  Do not do this for fibre insulated kilns, only brick.

Check on the kiln furniture – including shelves, boards, supports. Are they kiln washed and without scrapes, scratches, gaps? Has the kiln wash been fired to full fuse temperature? In both cases, clean the used kiln wash off the shelf and renew.

Check that the shelves and other kiln furniture are without cracks.

Clean kiln furniture of dust and debris.

Check the level of any item newly placed in the kiln - e.g., mould, or shelf replacement - with a spirit level.

Two examples of two-way spirit levels

 Check on the conditions and placement of the thermocouple.

Check on the elements.  Some may be sagging or hanging out of their channels.  Use tweezers to bring the coils closer together.  This shortens the length of the element and it then can be pushed back into the channel.  It may not have to be done after each firing, but checking will catch things before sagging becomes a major problem.

When the shelf paper is exhausted lift out the thicker papers and vacuum the shelf.  The Thinfire and Papyrus papers can be vacuumed directly or gently swept up and placed in a container for disposal.  Do not introduce any moisture to help reduce the dust.  This is not good for the kiln or you, as it could induce shorting out of the elements.

Monthly

Electrical parts: check the elements and their connections (normally at back or side).

First unplug or switch off the power to the kiln.

Check the screws on the connectors for the element tails are tight. Loose connections cause the wire to vibrate at the connection during the power phase. They heat up enough to melt the wire at the connection. For a single element kiln, it will simply lose power.  In multiple element kilns the remaining elements work much harder to achieve the temperature and provide uneven heating.

If the connectors are badly corroded , they need to be replaced.  This can be done without replacing the elements. Unscrew the connectors and put new ones on.  If the connector is fused to the element wire, you need to cut the wire as close to the connector as possible to maintain a length of wire for the new connector to be fixed.

Check the condition of leads and plugs supplying power to the kiln.  Make sure they are sound, not frayed and not kinked. Replace any frayed parts.  Take out any kinks in the power supply cable.

Any support pins or wires should be firmly seated in the brick work or supported by sound hangers.

Check the level of the kiln floor and internal shelves on a regular basis and every time the kiln and its internal furniture is moved.

Making a schedule of maintenance checks and noting on it the dates checked is a good idea for those who need reminders.

Instagram as a place to sell

What it is

Instagram is a place to show work and get followers.  It is a photo and video sharing site owned by Facebook.  It is a place to tell visual stories that lead to direct message conversations that can lead to sales.  But it is not a direct selling site.

Developing a body of followers is a slow process requiring continued commitment.  Audiences tend to focus on the Instagram stories and videos. Talking to camera, showing your workspace, showing and telling about favourite products are some of the things you can do to make stories for Instagram.  Posting these images and videos is way to get feedback on new products by inviting people to react.

Using it

Instagram’s value is largely as a marketing tool.  It is not a place to do frequent or blatant selling.  There is a general lack of response to posts with an overt selling message.  But occasional on-line sales to a group of committed followers seem to work. Beware of the effort and cost of packaging and posting, though.

What to post?

Frequent posting is essential to developing and maintaining your group of followers.  Remember the title - Instagram.  Instant reporting of developments is important.  It develops the connection between what you are doing and your followers.  The things to concentrate on are such things as how the day has gone, stories, new venues and products.  Ask questions of followers to get feedback and conversations developing.

Some use Instagram as their main social media source.  Share anything in your life that you are comfortable with everyone knowing, and of course, how the business is developing.  In all this sharing be yourself, have your own voice.  Your postings need to be when there is news rather than at set times.  Your account becomes livelier and more personal when spontaneous.

Images

Good photographs are essential.  Photos and videos are the essence of Instagram.  Your photos need to have clear captions. The captions need to provide the context for each image. Some suggest that concentration should be on the captions, and then finding a photo to fit.  The captions and hashtags are the ways people find their way to your postings.  You need to think about the terms potential customers may use to find out about your kind of work.  There is no need to overload the images with hashtags.  A few well thought out terms will give better results.  Look at the kind of tags you would use to find items of interest outside your craft. The really important element is an emphasis on providing a story in all the postings.

Sharing

In addition to creating content, reciprocation of likes and comments is important.  This means you need to spend some time on the platform to help develop followers.  Instagram does assist in creating a community of followers and makers, especially if you connect with makers of similar things and exchange supportive chat.

Time commitment

There are suggestions that 80% of your time on Instagram should be building your brand, and partaking in the community. The rest of the time you can tell about new products, promotions, and answering questions that will help people in deciding on the purchase.  But, generating sales is difficult by use of only Instagram.

Location of Outlets

Galleries use Instagram too.  But it is mostly about raising awareness of their businesses, so sales on Instagram are incidental to them.  They use it to let people know about news of the gallery and artists, their interests, and promote their exhibitions.  For them it is about publicity. 

Their secondary use is by browsing and getting a sense of potential exhibiting artists as persons and what their expertise and audience may be.  This means that getting galleries as followers can be a way to maintain contact with galleries and get invitations to participate in events.

How Can Glass Enthusiasts use Instagram?

It may seem the emphasis of this post is on full time craft artists, but these things are applicable to any craftsperson who wants their work to be more widely known and purchased.

Anyone who is going to craft fairs needs to do a lot more than turn up with product.  Many times, I hear of people lamenting the poor attendance at an event.  Or, the concern that people don’t seem interested in buying your work.

The organiser of the craft event can do only a limited amount of promotion.  Their promotion will be largely general and untargeted.  Your promotion will be much more targeted, because it will be directed at your followers – an already interested audience.  If you can get your followers to attend the event, or spread knowledge of your attendance at an event, you have a greater chance of having a good event.

In summary, Instagram can be an element in building an audience for your glass work.  This can increase attendance of interested people at the events you are involved in, if you put effort into getting followers who appreciate your work.

Incompatibility or Annealing Stress?

It is sometimes difficult to determine what the cause of any cracks might be.  There are a variety of possibilities with pot melts and other high temperature processes.

Surface of slumped melt

Cracks only on the top of a piece indicate a stress problem. Yes, there may have been a shift in compatibility, due to long soaks at high temperature. It would be a small shift though, or the cracks would have progressed to be more obvious.

Possibilities of healing the cracks relate to the kind of stress. If the stress is from incompatibilities, there is no means of healing the cracks.  Further firing may worsen the problem. 

If the stress cracks are due to the annealing being inadequate, a very slow rise in temperature to about 40°C above the annealing point before going to a full fuse is required. To heal the crack, you will then need to go to full fuse temperature.  This may require dams to reduce the expansion of the piece, if that is critical. Then follow with an annealing that has a longer soak and slower anneal cool than previously used.

Slumping will not help. Yes, the compression may bring the open cracks together, but temperatures are not high enough to heal (if possible) any cracks or imperfections. 

The pattern of splits on the bottom of the slumped piece

In this case splits developed on the bottom during the slumping. The splits on the bottom - if not due to incompatibilities - are usually due to a too rapid rate of advance in temperature in the early stage of the heat up. 

If it is thought that the cracks occurred as a mistaken combination of, say Bullseye and Oceanside, the stress would have been great enough to break the piece completely.  There is too great a mismatch of these two glasses to co-exist in one piece.  Of course, if only one or a few pieces were mixed in, this kind of small crack could occur, but it will normally be around a particular colour.

It is possible that different manufacturers’ glasses were used in this piece. The differences in compatibility can produce mild stress within a piece that do not break immediately.  In high temperature process like this, the incompatibilities will be exaggerated more than in thinner pieces fired at lower temperatures.

More detailed information is available in the e-book: Low Temperature Kilnforming.