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I suppose like most hobbies and art projects, it is first and foremost almost essential to have and interest in design, try and have reasons for liking or disliking certain designs or elements in designs, much like cooking, it is necessary to have a desire to create a flavour and work towards this end. Painting on glass is possibly a very simple process but is at its best when the glass object is part of the design or taken into consideration when planning the design, also the use to which the glass is to be subsequently put, should guide the type of paint and the design. Some acrylics are transparent, others very opaque, can be visualised through the object, or, like a plate, the glass can act as a protective screen. Working in opaque can also mean that you are working in reverse order, painting the highlights first and then working through the mid range to the background colours, no room for mistakes and needing to have the design well sorted out before hand. Transparent colours have also the difficulty of needing to have tested the colour and overlapping colours, in advance, on a trial piece of glass, the quality of the paint and the colours you choose are a factor in the final design.
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GLASS ENAMELS Although traditional painting on stained glass is probably the most common way of painting on glass, painting with glass enamels has grown significantly in popularity the last few years. The range of colors is extensive, and the ability to mix colors means that a virtually unlimited palette is available. These "paints," which like traditional stained glass paints are actually finely ground glass particles with a relatively low melting point, are available in both transparent and opaque colors. They are applied, then fired onto the glass using a kiln. Because glass enamels are made of tiny glass particles, care must be taken to ensure that they are compatible with the base glass being painted on. As with any other glass, using incompatible enamel will result in cracking or poor adhesion. Care must also be taken when using glass enamels that the fine particles are not inhaled. A respirator or mask is recommended to prevent this, as inhaling fine glass particles can cause silicosis, a serious and potentially fatal lung condition. There are a number of ways in which glass enamels may be applied, but in most cases the enamels are applied and fired in several layers. This maintains the integrity of the colors and also helps to achieve effects that would not be possible in a single firing. It is not uncommon for enamels to require four or five or more firings before the work is complete.  To apply enamels with a brush, you must first mix the glass particles with a liquid (called a "medium") to obtain a paint-like consistency. Mediums may be oil or water-based, but water-based mediums have the advantage of generally being safer and easier to clean up. The key criterion is that the medium fires clear without leaving a residue. Commercial preparations are available, but good results have been reported from using substances as common as 7-UP (or Sprite, if you prefer). The proper consistency for painting is approximately one part enamel to two parts medium, but this can vary depending on the particular enamels used. It's a good idea to mix the paints on a smooth surface (a sheet of window glass is ideal), adding the water drop by drop until the desired consistency is reached. Sometimes the paint will dry out a bit during painting and you will need to add a few extra drops of water. Any brush may be used, but recognize that transparent enamels tend to show brush marks. Take advantage of this by using the brush to create desirable patterns and textures. (Opaque enamels are less likely to exhibit this trait.) Once application is complete, the enamels should be allowed to dry prior to being kiln-fired. Enamels will mature at various temperatures, with opaques generally requiring higher temperatures (around 1450 degrees Fahrenheit) and transparents needing only to be fired to around 1200 degrees F. For enamels that fire at this lower temperature, it is possible to both slump and fire on enamels in the same firing. Many of these lower-firing enamels contain lead, so care should be taken not to use them on food-bearing surfaces. It's possible to achieve significantly different results by varying the method of brush application. The enamels can be mixed very thin and splattered onto the glass a la Jackson Pollock. They can be applied, allowed to dry, then scratched partially off to yield interesting patterns. Often, the best results come from very thin applications and multiple firings; thicker applications tend to result in a dark, muddy appearance. Also, many glass artists use "reverse painting" techniques. This approach, which is contrary to "normal" painting techniques which start with the background and add details as a final step, starts on the backside of the sheet of glass. Working from the top layers to the bottom, successive layers of paint are added and fired until the picture is complete. Although the approach appears strange at first, it results in a work with an exceptionally clear and glossy surface. Remember that when firing enamels you must follow the normal warm glass procedures to heat, anneal, and cool the glass to prevent cracking and thermal shock. Fired properly, the enamels will bond to the glass, resulting in a permanent, lustrous finish.  Glass enamels can also be applied dry. To do this, simply place a small amount of enamel powder in a sifter and sift. You can add interest by drawing patterns in the sifted powder or masking off a portion of the glass "canvas" to control where the powder goes. If you work with glass enamels, it's a good idea to wear a mask to keep from inhaling the glass particles. This is especially good advice if you are sifting and working with dry enamels, which can easily become airborne.  Glass Types and Forms In addition to compatibility, glass artists also differentiate among different types of glass in many different ways. One of the major criteria for differentiation is the transparency of the glass. Opaque glasses that do not transmit light are generally referred to as "opaques", as "opalescent" glasses, or as "opals." See-through glasses of various colors are usually called "transparent" or "cathedral" glasses. Combining more than one different opalescent or cathedral glass or color in a single kiln-formed work is common. Several different companies offer lines of tested compatible glass, with the largest and most popular being Bullseye and Spectrum. Other companies offering tested compatible glass include Uroboros, Effetre (Moretti), Wasser, and Gaffer. Bullseye, which has produced tested compatible glass since the 1970's, is generally acknowledged as the market leader, with a broader product offering than Spectrum or other brands. Spectrum's tested compatible program, initially launched in Spring 2000, contained glasses made by both Spectrum and Uroboros, and is marketed under the "System 96" name. Although the two product lines behave similarly in the kiln, they are not compatible, so most glass artists and hobbyists choose one or the other brand as their primary glass for fusing and slumping. Virtually any stained glass, whether tested compatible or not, can be treated with an iridescent coating that causes the treated side of the glass to take on a metallic sheen. Some liken this effect to a shimmering rainbow. The shimmer goes away when the piece is lit from behind, allowing the normal color of the glass to shine through. Another popular kind of glass coating, called "dichroic", has the unusual property of reflecting one color while it transmits another. This means that the different colors can be viewed by examining the glass at different angles. This unique glass is manufactured by spraying a thin chemical film on the glass. This must be done in a controlled environment in a vacuum chamber, making dichroic glass one of the most expensive glasses made for kiln-forming. Because of this expense, dichroic glass is more commonly used in jewelry and similar items, or as an accent in larger scale fusing projects. One final type of glass that is often used for kiln-forming is "float" glass. Made by "floating" molten glass on a bath of molten tin, float glass is better known as common window glass. It is inexpensive and widely available. It also works well in the kiln, but care should be taken to test for compatibility if different brands and types of float glass are mixed together. If at all possible, cut pieces to be fused together from the same glass sheet. Although some colored varieties of float glass are available, it is most commonly found in a clear (often slightly greenish) formulation. It tends to slump and fuse at slightly higher temperatures than most art glass (about 75 to 100 degrees F higher), and can be prone to devitrification. Its COE depends on the specific formulation used and can be as low as 83 or as high as 90, but it generally ranges from 85 to 87.  KILN-FORMING PROCESSES AND TEMPERATURES
Note that the temperatures given are for typical fusible art glasses. Other kinds of glass may require different temperatures.  |
There are so many reasons to be thanking cows, clearly the milk is very good for you and they provide meat for those that are carnivorous, if you are enterprising and have space for cows, they can provide the methane for use as a fuel, they could pull your plough and cart and there product of milk can paint your house.
CASEIN. Chemistry: Casein Glue
1870 Milk Paint Formula
