Enlargement without Maths

 Setting out an enlargement grid can be done without the mathematics of ratios.  It uses an old method of estimated interval size and angles relating to the ends of the estimation and the width of the design.  This gives the method in simple images.

     Start with your original design

Draw line at a shallow angle from one corner

Determine number of grid lines (say 10) along the bottom edge.  Choose a length approximately the size needed for the grid.  Mark out the number of divisions with dividers or compass on that slope.

Connect the final mark with the corner at the end of the line started on.  Place a right angle on that line.

   Fix a long straight edge under that right angle and fix it so it does not move

·        Transfer the marks on the sloped line to the edge of the image.

This gives ten equal divisions. Adjust the divider opening to the width of the division.

Use dividers with this opening to transfer the division size to the other edge.

Do this on all four edges if a rectangle.

Do the same process for the enlarged size.

Draw a slope

Estimate the size of the division.  Mark that estimate on the slope as for the original design.  Fix a right angle between the end of the slope marks and the corner of the design.  Fix the straight edge and mark off the divisions on the enlarged size.  Transfer these divisions with the new division opening of the dividers

Draw the grid.

Note where the design crosses the grid lines. Transfer marks onto the enlarged grid proportionally.  To avoid confusion, mark one line in at a time.

An intersection of the design line two thirds up the design grid vertical gets a mark two thirds up the corresponding enlarged vertical.  The same with horizontal grid lines.  Connect the dots one line at a time in pencil.  They can be altered later and erased once the final lines are inked in.

 

Enlarging Designs by Hand

Not everyone has easy access to enlarging copiers.  Even when they are available, large enlargement ratios produce distortions.  This presents a dilemma when a big enlargement is needed.  Is it necessary to redraw the whole design at a larger scale?  There is a way to enlarge a design without machines or needing to redraw the whole.  This is a description of how it can be done.

The old fashioned way to enlarge an image is to grid the smaller original.  This grid is normally made in squares of convenient size.  The grid size does not have to fit evenly into the dimensions of the original.  It is easier if the longest side has a size of grid that fits evenly into it.  This probably means there will be an uneven fit of the square grid on the other dimension.  This is not a big problem. 

The size of the grid is related to the amount of detail.  More detailed original images need smaller squares than images with less detail.  Detailed images may require a 1cm/0.375” square grid or less.  This is to ensure all the detail is included in the enlarged image.  A less detailed original may only need a 2.5cm/1.0” grid.

Also, bigger enlargements require more squares on the original than smaller enlargements.  If you are enlarging more than three times, you should be looking toward smaller squares for the grid.  This allows you to maintain the curves and angles more easily on the enlarged copy.  Smaller enlargements can have a larger grid size.  The relevance of the grid size becomes apparent when you set out the enlarged grid.

It is useful to use a set of dividers to ensure the repeated grid size is set out on the boundaries of the original image size.  Once set, the distance between the two points of the dividers remains constant as you “walk” them along the boundaries.  If you mark all four sides of the image with the dividers, you only need a straight edge to draw the grid lines.  I draw the lines in pencil. Then if I make any mistakes, I can erase the lines and set new ones.

On another piece of paper set out the new enlarged size boundaries.  If you have set the boundaries at the correct size relative to the original, the new grid should fit evenly into the long dimension.  Multiply the grid size on the original by the enlargement ratio.  This gives you the size of the enlargement grid.  Set your dividers to this and mark off the enlarged grid.

In fact, most of the time, the difference between the final enlarged and the original size determines the enlargement ratio.  To get this ratio, divide the enlarged size by the original size to get the ratio.  This ratio needs to be applied to the new grid size.  If it does not fit well, adjust the dividers to the required size and mark the length again.

Example:

·        The approved design is 10 by 15cm/ 4” by 6”

·        The final size is to be 60 by 91.5cm/ 24” by 36” (assuming your design is in the same proportions as the final size).

·        Assuming your design is of moderate detail, squares of 1cm/ 0.39” might be enough to capture the detail.  For more detail, smaller squares would be required.

·        To determine the size of the squares in the full size design, divide the final size by the design size.  I prefer to use the bottom side for this calculation, but either side will work. The bottom side of the full size is 60cm, and the design is 10cm. The division shows that the squares on the full size need to be in a ratio of 1:6.0. This means the squares on the full size need to be 6.0cm/ 2.4”.

·        If this appears to be too large a grid, the squares can be divided to capture more detail.

 

The next blog post will show how to divide the design and full size without using maths at all.

Having marked the edges of the design with the grid sizes, draw the grid across the design.  Do this in pencil, so the grid lines can be erased when the enlargement is completed. This will give intersections between the design lines and both the grids. 

Enlarging involves marking these intersections on the full size grid in proportional locations.  E.g., if on the design the intersection on the grid line is 2/3 up the grid square.  On the large one mark it also 2/3 up on the corresponding square. Do one line at a time to avoid confusion.  When as much of the line intersections as you want for that element are transferred, draw the line in on the full size.  There will need to be some adjustment when finished, so use a pencil for all these operations.

When satisfied with the look of the full size, ink in the lines and erase the grid and any unwanted lines. You now have a full size cartoon to work with. 

Manually enlarging a design is most useful when you do not have access to machines, and when the enlargement is more than two times.  Machines distort the lines at high magnifications and require checking and often redrawing of edges and various elements anyway.

Firing cremains to avoid bubbles

Firing with cremation remains is very similar to firing with any organic material encapsulated into glass.

Design

There are several possible design approaches.

Drilling holes is one method to avoid bubbles.  You can drill the base, put the remains on top and then cap.  Place the whole assembly on 1mm fibre paper to allow the air to migrate out through the hole and fibre paper under the glass.

Alternatively, you fire upside down and then fire polish the top.  Place the eventual top down onto the kiln washed shelf or Thinfire. Place the remains on the glass and cap with the glass that has the hole drilled.  Fire, then clean, turn over and fire polish the final top surface.

Design the piece and placing so there is a gap at the edge. 

This gives a route for air to escape.  If there is any gap left after fusing, it can be filled with a bit of super glue or other clear glue. 

Another method is to place pieces of frit or stringer at the very edge of the base glass to allow air out from under the centre of the piece.

If you do not need to concentrate the cremains in one area, you can disperse the material evenly across the piece to reduce the possibility of large bubbles.  The air and gasses can migrate to the edge through the particles, just as happens with powder sprinkled between layers of glass.

You can combine some of these methods as they are not mutually exclusive.

Firing

Fusing these pieces is, in principle, the same as encapsulating any organic material within the glass.  Slow advances are required with a 3 to 4-hour soak at around 600°C to burn out any residual organic material just as you might for thick vegetable matter.  You can add another bubble squeeze soak of an hour or so at around 650°C to gradually push any remaining air out from between the particles.  Then advance to the fusing temperature and anneal as usual.

Observation

The importance of Observation (and recording)

Observing what you, or the kiln, is doing whether you are using a cartoon, or a schedule obtained from elsewhere – including the kiln manufacturer – means that you will learn much more quickly as you progress.  You will be able to alter things as you go.  This applies to all stages of the piece from design to removing the piece from the kiln.

The Design

Once you have made your design – whether as a drawing or a mock-up – look at it.  Really look at it.  Look at it from a distance, climb a ladder if you can’t pin it on a wall and look down on it.  Look at it from the sides so you have an oblique angle view.  Turn it upside down to confuse your expectations and so see what is really there.  Look at it, using a mirror to see if it still looks good. Make the alterations you need as you go along to get the look you want and then repeat the process until you are happy.

Assembly

Observe how you have put the piece together.  Do the pieces fit?

Is everything in the right place? Are the colours right? Does it match your vision – symmetrical or asymmetrical?   Do these things as you progress, so you become aware of the process and its rhythm.

Firing

Once you have determined your schedule, you cannot just leave the piece. If you are new to fusing, you need to observe the stages of firings to begin to understand what is happening to the glass at various temperatures and rates of advance. You would not put a cake into the oven and leave it without checking on it from time to time. Why would you fail to observe a much more expensive process?

Even when you are experienced  - observation of new layups, new processes and anything you haven’t done several times before - you need to know how things are progressing during the firing.

Observing a firing is relatively simple.  You need to check on two things:

·   Check for a too rapid rate of advance.  Peek into the kiln at around 540C to see if the piece is still whole.  If not, you can abort the firing and progress to fixing or move on to another project.

·   Check to see when the desired shape has been achieved.  Peeking to see if the slump is complete or needs more time is important to getting the shape right.  Peek to determine if the tack fuse has been achieved.  When it has, advance to the next segment to avoid over firing.  If it hasn’t, add time to the schedule to get it right.

Recording

It is not enough to simply observe.  You need to record what you intended and the results you achieved.  That includes what you did to get things right as well as wrong.  What did you do to correct elements?  These are all things that you will need to refer to in the future.

The key to rapid learning is observation and recording what you see.

Textured Side

There is a little concern about whether the textured side of the glass pieces in leaded and copper foiled glass should be towards the inside or outside.

The traditional advice is to have the textured side toward the inside.  This is based on the piece being used as a window. It is easier to keep the weather side clean if the smooth side is on the outside. The same thinking leads to the recommendation to allow the cemented panel to rest with the smooth (outside) down.  This minimises the thickness of the putty and so allows less water to collect on the outside horizontal leads.

If the window is not primary glazing, it does not matter which side, nor how consistent you are in placing the glass.  It becomes a matter of aesthetics – which ever way you prefer is fine if it gives you the effect you want.

There is a small visual effect if you are using transparent glass.  There is slightly more dispersion of light if the textured side is outwards. 

Placing the textured side inwards can be useful if you wish to indicate a rough surface contrasting with a smoother one.

These considerations show that the placing of the textured side is largely determined by the function of the panel and the aesthetics applied.

Light and Dark in Designs

Chiaroscuro – This word borrowed from Italian ("light and shade" or "dark") refers to the modelling of volume by boldly contrasting light and shade. 

Glass artists need to be very cognisant of light and dark, both in terms of colour selection and in terms of density. A very thick dense glass of a dark shade of any colour will create a much more intense darkness than glass that is thinner and less dense.

In terms of colour, lighter hues go where the sun shines or where the eye is to be drawn. Pastel shades indicate brightness and light. Within some opalescent and art glasses it is possible to find a shade of colour graduating to white or light yellow. 

Shading can be achieved by using the white areas to indicate where light is falling. A denser dark glass can be used to indicate where light does not fall, or where very little light can filter through. It can also play the part of negative space.

Sometimes, it is useful to use a monochrome scheme to assist in determining where the light and dark should be, as in this pear:

The contrast between light and dark can be used in several ways. Darkness can indicate depth of field or distance when used in a general landscape. Or, it can be used to bring a foreground out, making other elements more vivid.

The key thing to remember in using stained glass is to not be afraid of dark glasses. They can very useful, even if of very odd hues of colour.

Drawing an Oval

Need to draw an oval for a panel? Here's how:

• Set out the long axis horizontally.
• Set out the short axis at the half way point of the long axis at right angles to the horizontal.
• Measure half the short axis on each side of the long, horizontal axis.
• Calculate half the measurement of the longest line. In this example the long line is 340mm and the short axis is 200mm long.  
• Half the long axis is 170mm.
• Use that as a diagonal measurement from the end of the vertical axis. 

• Measuring from the end of the shortest line, mark off this amount on the longest line, right and left. You can use a ruler or compass set to the correct length, both will work.

• Insert a pin at both these points.

• Place a piece of thread, string - or in this case a quick release tie - round one pin. Tie a knot in the thread at the far end of the longest line.

• Put a pencil inside the loop. Pull the thread taut and begin to draw the oval.  Keep the tension even throughout the drawing to avoid a lopsided oval.

For a leaded panel, the space occupied by the lead came will need to be accounted for in the measuring of the dimensions.

This is a simple method that does not require much in the way of tools, but its accuracy is a result of the degree of attention to details.

Thinking About Design

To think about design, you need a vocabulary to describe the object. This needs to be combined with a structure of principles. What follows is an outline to structure your thinking about design.  This is based on the writing of Burton Wasserman in Spark the Creative Flame, Making the Journey from Craft to Art, by Paul J Stankard, 2013.

First there is the vocabulary to structure the conversation about design. The elements of this are “… point, line, plane, texture, colour, pattern, density, interval, … space, … light, mass, and volume”

There are then principles of good design.  They relate to:

Unity – all the elements form a whole

Balance – note, not only symmetry

Rhythm – this can be repetition with or without variation

Emphasis – or contrast between a main element and the rest

Harmony – all the elements work together

These five principles of design together with the vocabulary of elements form the language of design and assist your critical thinking about expressing your design and realising it in the best way you can.  This thinking can be applied usefully to the critical appreciation of others’ works.

Line Widths for Cartoons

The lines for copper foil and lead cartoons need to be of different sizes.  Only a small width is required between glass pieces in copper foil.  This allowance is for the two thicknesses of foil and a space for the solder to run through from front side to the back side.  In leaded glass a wider line is needed to allow for the width of the heart of the came.

On cartoons for different methods, draw the lines in the appropriate width.  For copper foil this width is ca. 0.8mm.  This can be accomplished with a ball point pen or fine felt tip. 

For leaded glass panels, a thicker line of ca. 1.6mm is required. A bullet tipped felt pen is usually appropriate, if it is not worn down at all.

A cartoon for fused glass should use the finest line possible, as the glass pieces will be in direct contact (ideally) with each other.  As in copper foil, a ball point or fine felt tipped pen will be appropriate.

Large Bubbles

cambridgecreativenetwork.co.uk

Some times you want large bubbles, but when you don't, you need to know about the causes of, and ways to prevent, bubbles.

Causes and prevention of most large bubbles relate to volume control, layup, rate of advance and top temperature.

Volume control. We all know that glass tends toward being 6-7mm thick at full fuse temperatures. Any less volume and the glass thickens at the edges, so trapping air under the glass which will push up and through given enough time and temperature.

Layup. The lack of volume control is compounded by layups which do not allow the air to escape from under the edges of the piece.

Rate of advance. These two problems are compounded by asap, or even just rapid, increases in temperature. The glass softens quickly and the air finds it easier to push the glass up than to escape from under the edges. Slowing down is part of the answer.

Top temperature. A high top temperature softens the glass to the extent that any lack in volume control, layups that have hollows or traps for air, and rapid increases in temperature all allow the expanding air (and there will always be some) underneath the glass to push up and often through the glass.

These factors reinforce the Low and Slow mantra.

Other factors can promote bubbles, although the ones above are the most common. Debris between the glass and the shelf, or between glass layers can cause bubbles, given the right conditions. Small shallow indentations in the shelf can be the source of bubbles from underneath the glass. This can be identified by observing where the bubbles occur in relation to the shelf.

There are some things that can be done to reduce the likelihood of bubbles:

Internal bubbles

Avoidance

Heating

Rapid firing

Damaged shelves

Supports

Flip and Fire

Glue

Disguising Joints in Fusing

One advantage of fusing over leading or copper foiling is that shapes impossible to cut as a single piece can be made from multiple pieces. However these joints often show up in the finished work.

You are always more likely to have the joints show when the cut coloured glass is on the bottom. The infra-red heat of the kiln elements goes through the clear glass to the coloured below, allowing it to soften first. As the glass underneath softens and pulls in, it allows the top glass to sink into the space. Upon cooling the seam is kept open even sometimes showing a clear line at the joints.

Putting the clear as the base and the jointed pieces on the top has a better chance of having the joints fully fuse together. There is no glass above to spread the pieces apart.

When you need the joints to be concealed, you can put a line of powder the same colour of glass over the joint. This line should be slightly rounded above the surface along the joint to account for the reduction in volume as it fuses. When it is two colours meeting, using powder of the same colour as the darker glass is most successful.

Fusing to a contour fuse for 10 minutes is normally hot enough, but taking the piece to a flat fuse – again for 10 mins - will certainly be enough to fully melt the powder into the joint.

Radiating Lines

In designs for leaded and copper foiled glass it is important to avoid lines radiating from a single point. Some of these reasons are:

It is important to reduce the number of lines that meet in any design to avoid a big bright solder place in a panel.

Example of pattern with radiating lines

It makes for large solder blobs, especially on leaded glass panels, and therefore provides a focus where one may not be wanted or required.

The difference between the harder solder and softer lead came leads - over time - to cracks in the lead at the edge of the thick solder blob.

In leaded and copper foiled glass it is a point of weakness, as there are likely to be multiple thin or tapering pieces of glass that are liable to fracture early in the life of the panel.

Methods of Avoiding

This umbrella image avoids long narrow pieces by having the ribs and supports crossing to make short narrow pieces

Narrow tapering pieces can be compensated for by making the narrow parts shorter than the wider parts of the taper – although this does add to the density of lead and solder around the termination point. There is a difficulty in adapting single radiating points in a drawing to the practicalities of the medium of glass. Examination of older panels (in either technique) will show some of the problems of thin tapering pieces. It is obvious in older windows, especially in the Victorian Era, when tapered pieces where in their glory. Almost always, the tips are broken. It is the nature of glass, and goes back to knowing how the medium will react to the conditions you create.

The central circle avoids joining all the radiating lines at one point

Good design will avoid multiple radiating pieces from a single point of origin.

It is not possible to make a neat termination by joining half a dozen tapers at one point. The finished piece will not look like it did when it was drawn out with a pencil. You can pencil in a termination with six points, ending at one point and it may look good, but when you draw the design with the width of the led or foil will show the clumsy nature of the design with a large termination point.

As you can see, the answer starts with the design, before you cut and foil, or fit the came to the glass. Art is not about the physical placement of what you see in your mind, as much as it is about the "illusion" you are creating that you want others to see. That starts with the design, and avoiding something that you know is going to give you a problem.

It is not possible to make a neat termination by joining half a dozen tapers at one point. The finished piece will not look like it did when it was drawn out with a pencil. 

Example of a design that will present difficulties at the centre

You can pencil in a termination with six points, ending at one point and it may look good, but when you draw the design with the width of the led or foil will show the clumsy nature of the design with a large termination point. As you can see, the answer starts with the design, before you cut and foil, or fit the came to the glass. Art is not about the physical placement of what you see in your mind, as much as it is about the "illusion" you are creating that you want others to see. That starts with the design, and avoiding something that you know is going to give you a problem.

Avoiding Large Bubbles

“I tried small projects and they turned out fine. I have a 12" square with an emblem in the centre and a border set in slightly from the sides. Most of the glass is only the one layer. Both firings produced huge bubbles in the areas where the glass was only one thickness.”

Scale does matter. What can be done at a small scale does not always directly transfer to a larger scale.

The first problem this project created was using only one layer as the base. Glass has a surface tension which means that it tries to become 6-7 mm thick. One layer is only half that. As it thickens at the edges, it traps the air under the other parts of the glass, and as the glass continues to soften the expanding air bubbles come up through the thin parts of the glass.

Using two layers of glass with the design on top will ease the problem.

The design is the second problem. The weight of the border makes it even more difficult for the air to get out from under the glass.

Although having two layers of glass will reduce the problem, think about ways to make the border incorporated with the second layer of glass, so the weight of the glass at the perimeter is not greater than the interior.

The third problem is that there is not a bubble squeeze in the schedule (elsewhere in the query). The soak of 10 minutes at 538C is not necessary. You do need a soak at a point between 650C and 677C - this is the bubble squeeze temperature range. It is also the slump temperature, so you can determine what the bubble squeeze should be for your glass by what the slump temperature is.

The bubble squeeze can be accomplished by a half hour soak at the slump temperature, or by a slow rise from 50C below the slump temperature – taking an hour or so, depending on the size of the piece.

A fourth problem is the separator is batt (kiln) wash, the edges of the glass conform to the batt wash, resisting the movement of air from under the glass.

You may need to change to fibre paper for single layer pieces, as that allows more air out. Thinfire may be enough, but you can put it over 0.5 mm fibre paper. For a smoother finish, sprinkle powdered batt wash over the fibre paper and smooth it with a plasterer's float or a piece of window glass if you don't want to use Thinfire.

Lastly, don't use the pre-programmed schedules in your kiln's controller.

Look at the glass manufacturer's website. Bullseye, Spectrum and Uroboros give basic firing schedules that work with minimal adjustment. I don't understand why kin manufacturers don't simply refer to the sites to give their customers good advice, instead of the pre-programmed stuff.