The
very cheapest hair spray works well with glass paint, if you need to
transfer your painted glass to another place for firing. Complete the painting and then spray with cheap hair spray as you would to fix
a charcoal drawing. This will hold the paint firmly during transport
and does not affect the paint during firing.
Wednesday 15 May 2013
Friday 10 May 2013
Tracing on Opalescent Glass
Opalescent
and dense glass presents problems as the usual method of tracing the
image through the glass is not possible. If you first spray the
glass with a cheap hair spray, this gives a “toothed” surface to
the glass. Then using carbon paper an image can be transferred.
However, the carbon paper leaves a greasy residue, so water based
paint will not take, but an oil medium will.
Sunday 5 May 2013
Matting
Oil,
and Water and Gum as Media for Matting by Dick Millard [edited from a
discussion]
Oil has been used, I believe, since the 16th Century, and certainly up through the 1970's to today. It is used wherever it is determined it should be used, and one is sufficiently informed and facile to use it in a manner of delivering its full and lovely potential.
First
of all, oil is not characteristically employed as a matt, out of
which, by the negative process, one "takes out lights". In
overwhelming instances, with which I am acquainted, it is used as a
shading material applied over a pre applied and "worked"
under matt of water and gum base.
This
provides the required "tooth" to provide both a degree of
adherence and ease of application.
So,
I would suggest an oil matting, or a shading application over a
smooth glass surface, would be generally problematical!
Add
a bit more gum to your water under matt which will reduce the
necessity to fire that matt, which changes the character of the
desired "tooth". The purpose of the "tooth" to
receive the oil matt is also to provide "porosity" as an
"absorbant", which additionally holds the oil mixed paint
to the matt. Otherwise, the oil remains too liquid and does not float
in a controlled fashion. It will require a much dryer application of
kerosene, or increased absorption by additional blending.
I
had a large landscape piece, hills in the back ground, that I matted
and applied an alcohol mat too, but I was lifting the water mat
trying to cover it with alcohol, so I added more gum to my mat and
that did the trick. I also used a very soft Chinese brush. I have
found that firing the mat first and looses tooth.
I
have noticed over time that some people seem to have the impression
that the less gum used, the better. I advise not to use an excessive
amount of gum arabic, as a soft matt, with a soft touch produces a
soft look. This is interpreted to mean 'less is better'. That is
true, but only up to a point. If too little gum is used, or none, it
will come off as if it were flour or mud diluted with water and
applied. Too little gum severely jeopardizes any opportunity to
produce soft gradation from the highlight to the untouched matt.
Tuesday 30 April 2013
Tracing with a Pen
Example of a pen nib |
Using
paint mixed with essential oil or turpentine and with a fine mapping pen for small lettering
works well, as the oil flows better than water. Although with
practice, a water based paint can be used with a pen, but it is a
little tedious as the pen has to be loaded frequently with a tracing
brush and constantly cleaned as the water dries quickly.
Thursday 25 April 2013
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.
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.
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.
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.
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.
Tuesday 23 April 2013
Aperture Drops Blank Sizes
As the glass drops through the aperture, it stretches,
but the whole substance of the piece is drawn toward the hole. If there is not
enough spare glass around the hole, the whole piece will be drawn through the
aperture.
There is a minimum size of the glass in relation to the
size of the drop out hole. Up to some maximum size, the greater the diameter of
the hole the
greater the amount of spare glass there needs to be.
Also relevant is the depth of the drop. A shallow drop needs only a few centimetres larger than the hole. While a deeper drop needs a greater amount of glass surrounding the hole.
I have found that for a 300mm diameter hole, with a 150mm drop the glass needs to be 35mm larger all around. Thus an aperture of 300mm needs to be at least of 370mm diameter for this 150mm drop. I have done drops with 550mm diameters with only a 650mm diameter blank. This indicates to me that there is an amount of spare glass that will be sufficient even for larger diameter drops, but I have not found it yet. For a large drop with an aperture of 500mm and a depth of 350mm, I used a 100mm margin. This gave a disc of 700mm. It successfully dropped with the rim moving only about 20mm.
One element that can reduce the size of the blank is to make an inclined collar around the aperture of the drop mould.
This idea is based on the observation that as the glass begins to fall through the aperture, the outer edges of the glass rise from the mould surface so the glass is resting only on the inner edge of the drop out mould.
This inclined drop out mould will be like a shallow bowl rim, but without a bottom. The glass blank then rests with only its outer edge on the collar. When the temperature increases to the point that the glass begins to slump, the glass will conform to the slope and so create enough friction to restrict the glass from falling through the aperture, although it is with a smaller than normal rim. The actual size of the rim for each size and depth will need to be determined by experience.
Saturday 20 April 2013
Temporarily Securing Panels
When installing panels into an window
opening or frame, you often need to secure it while you finish
puttying or use other forms of weather proofing.
If you use sprigs (headless nails) or
even carpet tacks, use them where there are leads meeting the
perimeter. There us less chance of a stray hammer strike hitting the
glass. It is more likely to strike the lead and so cushion the
impact to the panel. I also use a straight putty knife behind the
nail or sprig to avoid even the chance of a strike directly on the
lead.
These precautions, with suitable
modifications, are applicable to copper foiled and fused panels.
Monday 15 April 2013
Initial Heat Up Rates
Example of a graph of a heat up for industrial purposes |
There is quite a lot of information on
the annealing cool rates, but not so much on the initial heat up
rates. This is probably because the cooling rates are more critical
than the heat up. But everyone knows that you can heat the glass up
too quickly for its thickness.
My experience leads me to suggest some
heat up rates to 50C above the annealing temperature for circular and
nearly square full fused pieces. These have worked for me, but of
course, may not work in all kilns.
6mm heat up at 160ºC/hr
12mm heat up at 110ºC/hr
19mm heat up at 50ºC/hr
25mm heat up at 30ºC/hr
In general, these heat up rates are no
more than twice the initial annealing rate for the relevant
thickness. That is, the initial anneal cool for 6mm is 80C/hr; and for 12mm is 55C/hr. When you get to 25mm, my initial anneal cooling rate is only 15C/hr. So you can see how the doubling of the initial anneal cool works.
Tack fused and pointed pieces require
much more careful heating because of the differing thicknesses within
the piece, or the relative narrowness of one end or area in
comparison to other areas. The suggestion is that the heat up for
these should be at the rates suitable for items at least twice as
thick as the thickest part of the tack fused or tapered piece.
Wednesday 10 April 2013
Grinder Bit Height
If your grinder bit is too low or too
high the diamond surface will not grind the whole of the glass edge.
This can lead to chipping of the surface of the glass at the edges.
A good practice is to start with the
bit as high as possible to allow for differing thicknesses of glass.
As high as possible is with the bottom of the diamonds just below the
platform of the grinder. This will ensure that you can deal with
varying thicknesses of glass without immediate adjustment. You can
then lower the bit as it wears.
Of course, you need to ensure there is
adequate water reaching the grinding bit to avoid overheating the
glass, and to keep the dust from grinding from getting into the air.
Friday 5 April 2013
Mobile Glass Storage
Sometimes
people consider placing their glass storage onto wheels. It
is better to avoid wheels on glass storage for several reasons.
You
would need heavy duty wheels to cope with the weight. Glass is 2.5
times as heavy as water, so it does not take much volume to make a
really heavy glass case.
You do not need to move all your glass at once - a piece at at time is all that is needed. It will be safer, and in the end easier, to build your work bench nearer the glass.
There
are risks breakage while moving. The heavy glass store will vibrate
the glass within the storage, and any snags or obstructions while
moving the glass will increase the risk of breakage.
The
structure can become too heavy to move and so defeat the original
intention.
Saturday 30 March 2013
Antiquing Sandblasted Glass
Sometimes a
sandblasted area appears too white when finished. One method that
can be used to tone down the whiteness is to use low temperature
glass stainers' enamel.
The low
temperature enamels cure at temperatures between 530C and 580C
depending on the type and manufacturer. At this temperature the
glass is unlikely to change its shape. The jewellers and ceramics
enamels fire at higher temperatures and are not suitable.
Rub the dry
powder into the sandblasted area with a cloth or your fingers. The
advantage of using the powder dry is that it will not stick to the
smooth areas, although you may need to brush it out of any
depressions in fused glass.
Fire the glass to
the minimum temperature for the enamel, but for S96 or Bullseye try
to stay below 540C. This temperature will fix the paint to the
glass, but not change the shape of the sandblasting. Float glass will
not change if you go to 580C. If you go to higher temperatures, you
will go toward a satin effect and finally a smooth surface.
This technique
has the advantage of being able to introduce a subtle colour tone to
the sandblasted area. This enables you to match older glass that may
have a slight colour cast from the glass or materials it has become
encrusted with, such as nicotine.
This method
requires testing to get the right levels of colour, and the
temperature to balance the fixing of the enamel without changing the
sandblasted surface beyond your choice. So you need to prepare
several samples noting the amounts of enamel and temperatures used.
This has been
successful for me when replacing broken sandblasted door panels that
need to match the side lights. It removes the excessive whiteness of
the new panel and can blend to match the colour of the originals.
Monday 25 March 2013
Assembly of Circles and Irregular Shapes.
Leading
Circles
and ovals as well as irregular shapes significant support as leading
often involves sideways pressures to fit the lead to the pieces of
glass. Thus there are two main methods of support for the perimeter
of the panel.
You
can cut supporting pieces of glass to place around the perimeter.
These need to be cut to the outside of the perimeter cut line. These
supports must be in at least two or more pieces to enable the came to
be put in place progressively. You then assemble the perimeter lead
into it and continue to lead up as normal. The perimeter support can
also be made from thin plywood or similar materials. This can be
useful if the shape is to be repeated.
A
simple means of supporting irregular shapes while leading is to place
a number of nails around the inside edge of the cut line. There need
to be enough to support each piece of glass with at least two nails.
So you may need to add more nails to the initial set up. Build the
panel without the perimeter leads. When the interior is assembled,
put the perimeter came around the panel. Ensure the fully leaded
panel fits within the dimensions of the opening. Then solder as
normal.
Copper
foil
The
above methods can be used, but are often a bit heavy duty for copper
foil processes. Instead of glass, timber or nails you can use more
easily cut materials. Such things as stiff double walled cardboard,
foam board etc., are suitable for light duty. You can cut the
complete shape from these materials, but only good if no pressure is
used in fitting the pieces.
If
you are likely to repeat the shape and size, you can use plywood or
similar materials. Build inside the shape and remove it when the
whole is soldered on the first side.
Wednesday 20 March 2013
Disguising Joints in Fusing
You
can use powder or fine frit to conceal the joints in fusing. This is
most easily done before the first firing.
Fine
frit can be made from the off cuts from your prepared glass, or you
can buy powder of the correct colour. Where two colours meet use the
darker or denser colour of frit or powder over the joint. Push the
frit into place with a brush or stick to form a regular edge. You
should heap the frit over the joint to allow for the reduction in
volume when fused. This will not work as well on tack fusing as it
does on full fused projects.
Friday 15 March 2013
Placement of Pieces for Firing
Placing
pieces in the kiln, especially in oval and side fired kilns, is not
about filling the kiln completely. Kilns have hot and cold spots,
and the arrangement of the elements can have an effect too.
The
first thing to determine with a new kiln - and immediately after any
alterations to the kiln - is where the hot and cool areas of the kiln
are. There is an extensive guide to this on the Bullseye site. In
short, the method is to place strips of glass on short kiln furniture
all around the kiln at the level(s) you will be firing. These strips
should be of equal size and the kiln furniture the same distance
apart. Take the temperature slowly up to slumping temperature.
Observe when the visible glass pieces begin to slump. Let that
continue until they are about half way down. Then proceed to the
anneal. When cool you can open the kiln and see the areas where the
glass has slumped most – the hotter areas – and where it has
slumped least – the cooler areas. This will give you information
on areas to avoid if you want an even finish all around the edges.
If
your kiln is side fired, you need to consider the shelf placement in
relation to the elements. The best arrangement is to have one
element below the shelf and the shelf between elements so the radiant
heat is not directly onto the edge of the shelf as that may lead to
breaks.
Put
glass on the shelf as centrally as possible. If the glass must be
near the elements, baffle the glass from the direct radiant heat from
the side elements.
Sunday 10 March 2013
Glues in Kiln Forming
Glues
have two major uses in fusing. One is to stick things together after
being fused (cold fusing). The other is to hold things together
before fusing.
Holding
things together while preparing the piece to be transferred to the
kiln is a major use of low tack adhesives and glues. All of these
burn off a lot lower than the temperature at which the glass begins
to stick together. So, if you are gluing overhanging pieces, for
example, they can move after the glue has burned off. If you
are assembling pieces that will not stay in place while you are
putting it together, glue will not help get the final result you
want. If you are gluing to keep things stable while you move it
to the kiln, you may find everything is ok.
However,
glue tends to boil off if the temperature is raised too fast. During
this process, the effect of the boiling will move the glass pieces
that are most unstable. This also occurs if you use too much glue.
You should only use as much as will stick the pieces together. Also
too much glue leads to black spots and sometimes bubbles between the
layers of glass.
The
adhesives commonly used are the Bullseye product “Glastac”,
Elmer’s glue, diluted PVA - or school - glue. All of these take
varying times to dry and hold the glass pieces in place. So, a
popular alternative is hair spray. This is a lacquer which dries
almost instantly. It provides a thin film of adhesive and burns off
in the kiln with no residue. You should use the varieties with no
additives.
Glue
most often leads to problems or unexpected results, so several ways
have been used to achieve the desired results.
One
way to deal with unstable components on small pieces is to make a
large piece with a repetition of the design and cut it up after
fusing in to the sizes you want. Clean the pieces very well,
and then fire them again to at least fire polish to remove any
cutting or grinding marks.
An
alternative to using glue, especially at the edges where the pieces
are likely to move, is to use dams. My practice is to make the dams
slightly taller than the unfired piece and line with fibre paper. I
put 3 mm fibre paper against the dam, and thinfire against the glass.
Both of these should be 3 mm narrower than the final height of the
fused piece will be. This is to allow the glass to make a rounded
edge as it will not be able to stick to the fibre as it sinks down to
its final height.
Another
alternative to using glue is to fire the piece upside down, so that
the pieces do not have to be supported. This does require some
planning and forethought. You can draw the design in reverse on
thinfire, using different coloured pencils for the various layers to
help in building the piece up in reverse. You then cap the assembled
pieces with the piece that will become the bottom. Take the whole to
a tack fuse. Then clean very well to remove any residues from the
shelf. It is possible to sandblast and then clean to make sure there
are no residues left. Of course this is not possible if you are
using dichroic or iridised glass. Also note that iridised surfaces
and thinfire do not get on well – there is extreme pitting in the
iridised surface.
Tuesday 5 March 2013
Bones as Inclusions in Glass
The
major components of bones are calcium and organic materials making up
the marrow. If the bones are not old and weathered a very bad smell
will be produced. The organic material will cause bubbles. Finally,
it takes a long time to burn out the marrow, so it is best to use
bones that have weathered for a number of years.
Calcium
“erodes” during firing, so fine and thin bones will leave a
shadow of ash (or a big bubble if there is not a long bubble squeeze.
The bone has to be encased or trapped by the glass as it will not
stick permanently to the glass on its own.
It
can make dramatic shapes if the bones are arranged in novel ways to
represent other things. The whole of the bone does not need to be
encased, as the thicker parts will be strong enough to support
themselves.
Monday 25 February 2013
Hanging Sun Catchers
Unless
you are using some manufactured system or a frame, the most frequent
way to provide hanging points is to create a loop from copper wire.
Hangers
should originate in a solder bead that goes some way into the piece.
The loop's tail should lie a significant distance into the solder
line to ensure it does not pull the piece apart. If this is to remain
invisible, some planning will be required to allow the small extra
space between the foiled glass.
The
loops for hanging a piece of any size should not be soldered to the
perimeter foil without reference to the solder bead lines, as the
adhesive and foil are insufficient to hold the weight of the piece
without tearing.
Here the hanging loops could have been moved just a little to engage with the solder joints at the left ear and at the tail to make stronger hanging points |
Here the hanging points are at the solder joints giving strong hanging points |
Reinforcement of free hanging or projecting elements can be done by placing wire around the piece with a significant excess going along the perimeter in both directions. The supporting wire can go into the solder line, if it is a continuation of an edge of the free hanging piece.
The
strongest method is to wrap the wire around the whole perimeter of
the piece. Choose easily bent copper wire. This will be pretty
fine, but when soldered, will be strong enough support the whole
piece.
The
hanger can be made by leaving a loop of wire free. This way you can
hang from any convenient place on the perimeter. This loop can be
made by a single 180 degree twist in the wire, or by bending a loop
into the perimeter wire. In all cases you will need to tin the wire
to blend it with the rest of the piece.
This
perimeter wire can be simply butted at the start/finish of the wire.
It could be overlapped, but this is unnecessary on any piece where
this method is adequate for support. The start can be at the top or
bottom, although I prefer the top, so the wire is continuous from
loop to loop. The reason for continuing beyond the loops is to
provide support to all the edges of the sun catcher.
This single point hanger is at the strong point of the piece |
The left hanger is strong, but the right is weaker than if it had been attached to the right of the body |
This piece needs wire around the piece, especially to stabilise the tail and ears |
Wednesday 20 February 2013
Cleaning Magnets
When
making frit in steel containers the metal fragments need to be
removed using magnets. It can be very difficult to get the fragments
off the magnets.
A
solution has been suggested. Put the magnet into a small plastic bag
before use. After cleaning all the metal from the frit, take the bag
to the bin and remove it from the bag. The metal fragments will drop
off into the waste bin, leaving a clean magnet.
Friday 15 February 2013
Single Layer Firing
Preparing
a Single Layer for Further Kiln Work
There can be
circumstances where you do want to fire a single layer in building up
your project. This is more often difficult on rectangular than round
pieces.
Some of the
considerations are:
Temperature
Heat work
sizing
Cleaning after firing
Firing a 3 mm piece to
anything over a laminated tack fuse normally leads to the edges
drawing in creating a “dog bone” effect and often leading to
bubbles in the interior at higher fusing temperatures. So one
approach is to fire at low temperatures and accept relatively sharp
edges on the piece.
However the concept of
heat work can help in this situation. Glass reacts to the
accumulation of heat, so that slow advances or long soaks can achieve
the desired results at a lower temperature without – in this case –
getting the “dog bone” effect. This does require a bit of
experimentation. Keep good records of all the stages of
experimentation as the effects achieved with various combinations of
temperature and time will come in useful later.
It is possible that
using the concept of heat work will not be sufficient to achieve the
desired results. Then you need to consider placing your design in
the centre of a larger piece. Fire this to the lowest possible
temperature to achieve your results and then cut the fired piece to
size. You will need to fire polish or cold work the edges to get a
suitable finish on the edges.
The central white piece shows the results of single layer firing that could be altered by the above technique |
If you are going to
re-fire any of these single-layer pieces, you need to clean them very
well. Any dust or other contamination will be incorporated into the
final piece. This is especially true if you are combining a flip and
fire technique with this single-layer firing.
Sunday 10 February 2013
Slump Point Test
A
slump point test is useful when you wish to determine the approximate
annealing point of an unknown glass. The methodology follows:
Prepare
a strip of the glass 305mm x 25mm. Suspend this strip above the
shelf on 25mm pieces of kiln furniture. Leave a 275mm span between
the kiln furniture. A piece of kiln furniture also needs to be
placed on top of the glass to keep it in place.
Fire
at 200C per hour to ca.
550C, then fire at 50C/hour to about 700C. Observe frequently from
600C. Record the temperature when the middle of span touches the
shelf. This is also the slumping temperature of the glass when fired this way.
Subtract
40C from the “touch down” temperature
for the approximate annealing point temperature.
Tuesday 5 February 2013
Ceramic vs. Glass Kilns
The
purposes of these two types of kiln differ, so insulation properties
differ too. Ceramic kilns have high density brick insulation to
retain the heat and slowly cool the contents from the top temperature
to avoid breakage. Glass kilns have light weight insulation –
whether brick or fibre - to cool quickly from the top temperature to
avoid devitrification.
Considerations
Controllers
are necessary for controlled soaks and cooling on glass kilns. Much
simpler controls are sufficient for ceramics firings. So a ceramics
kiln needs to have a controller added. This is a significant cost.
If buying a ceramics kiln new for glass work, ensure it has a
controller that can be used for glass.
Heat
distribution
is different in the two. Glass kilns are shallow to get even heat
distribution to the surface of the glass. Ceramic kilns have
elements around the sides and frequently in the top, but may not have
any in the door, if it is not top loading. This means the heat
distribution in a ceramic kiln is not as even as in a glass kiln,
which is not a problem for ceramics as so much heat is retained at
the target temperature, it equalises as the kiln cools.
Loading
Ceramic
kilns up to 450 mm deep tend to be top loading, the ones with greater
depth tend to have doors. Glass kilns are shallower and tend to have
top – just the lid opens - , clamshell – the lid is the whole
chamber which opens giving direct access to the floor of the kiln -
or bell type – where the lid also forming the chamber is lifted
from the base of the kiln and often the base is on wheels so another
base of prepared work can be wheeled into place for firing before the
kiln has completely cooled.
Baffles
are required in ceramic kilns because the heat is greater nearer the
elements on the initial advance in temperature. These baffles avoid
premature sealing of the edges of pieces causing large bubbles.
Firing
on multiple
levels is
possible in ceramic once you have built up the experience.
Schedules
have to take into account the greater mass of insulation in ceramic
kilns.
Annealing
and cooling
tends to require different strategies to encourage the ceramics kiln
to cool fast enough in the devitrification range, but can have the
power turned off earlier after the annealing soak, because of the
slower cooling.
Ceramic
kilns are ideal for casting.
Cost
– ceramic kilns tend to cost less than glass ones and second hand
ones have been more widely available. That may be changing now with
the increasing popularity of glass fusing.
The electricity costs are marginally higher in ceramic kilns than glass, because the mass of brick to be heated up is greater..
The electricity costs are marginally higher in ceramic kilns than glass, because the mass of brick to be heated up is greater..
Space
-
Ceramic kilns tend to take up less floor space because they are deep
or tall rather than broad.
Wednesday 30 January 2013
Removing Kiln Wash
Kiln
wash can get stuck on items for a variety of reasons.
You can sandblast off the kiln wash and then proceed in either of the fashions above.
You can soak small pieces in tri-sodium citrate and then if necessary scrub with a wire brush – a brass wire brush is preferable to steel one to avoid scratching the glass.
A link to some methods of cleaning shelves is here.
A
variety of ways to remove the kiln wash are:
Grind
the kiln wash off with diamond hand pads, or small rotary tool with
wet sandpaper. You can then proceed to continue to grind with
successively fine grits until a polish is achieved, or you can fire
polish after a thorough cleaning.
Example of scrubbing kiln wash off |
You can sandblast off the kiln wash and then proceed in either of the fashions above.
You can soak small pieces in tri-sodium citrate and then if necessary scrub with a wire brush – a brass wire brush is preferable to steel one to avoid scratching the glass.
Another
solution is to place small items in an ultrasonic cleaner basket with
water and a little soap or proprietary cleaner. Leave for an hour or
two and they should be free of the kiln wash.
Friday 25 January 2013
Grinder Chipping Glass
There
are a number of reasons that may cause the grinder to chip the glass
surface. Some of the things to check are:
Too
much pressure
It
may be that you are pressing the glass into the grinder head too
hard. The grinder head should do the work. Firm rather than hard
pressure should be applied. If the grinder slows, it is an
indication that far too much pressure is being applied.
Insufficient
water supply
There
may be too little water reaching the head to lubricate the diamonds
and keep the glass cool. If you are getting a white paste or a powder
on or near the glass, you need to increase the water supply.
Worn
or damaged grinder bit/head
Inspect
your bit carefully for smooth areas showing that the diamonds have
been worn away. Also look for dents, and other irregularities on the
surface, indicating that the bit is damaged. Any dents or smooth
places on the bit cause a vibration that is similar to a tiny hammer
tapping the edge of the glass.
Grit
size
It
is possible that you may be using too coarse a grit on the grinder
bit/head. The more coarse the grit is the larger the chips will be
taken off the edge surfaces. Smaller grits take smaller chips off
the edges, and so are less obvious.
New
bits
Examples of the range and grit differences in grinding bits |
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