I often get asked how the kiln formed glass is made. How do I make pieces of glass become one? How do I create those designs? How do I get that shape?
Well... Here's a few answers to those questions. There are various forms of glass for kiln work, sheet glass (flat pieces of glass that come in various colours), frit (ground glass of different sizes), powders (the smallest, very fine form of frit), stringers, billets....the list is long. I mostly work with sheet glass and powders, occasionally I use frit but mostly clear to mix with powdered colours.
When working with sheet glass it must be cut to your desired shape and size, circles, squares and various shapes can be cut with some knowledge and technique.
Fusing is when more than one piece of glass is placed into a kiln and heated to a certain temperature until the glass is 'fused' or melted together. Different temperatures give different fused looks, either tacked, where the individual pieces keep their original shape, or full fused were the pieces melt completely into each other. And any where in-between.
Pieces then can be slumped or draped into shapes. Slumping is where the flat piece of glass is placed on top of a mould and heated just enough for the glass to 'slump' into the mould, and then cooled so it holds that desired shape. Draping is where the flat piece of glass is placed on top of a mould and heated enough for it to fall down over the mould, hence 'draped'. Other types of moulds can be used to different effects. My vases are created with 'drop-out' moulds. It basically looks like a donut, that sits on props so it is off the kiln floor. A flat designed piece is placed on top and heated until the middle section begins to slowly fall through the donut. A close eye needs to be kept on this to make sure the desired effect is accomplished.
I enjoy using powdered glass, it is very versatile and can create some amazing designs. The 'crackle' effect designs are created using layers upon layers of powders onto fiber paper (specialised 'paper' used in kilns that do not burn off). This technique was perfected by the glass artist Bob Leatherbarrow. It creates beautiful organic designs full of colour and texture.
I also enjoy using powders dry, or 'wet' to creat 'paintings'. Thickness and styles depend on the final pieces, often looking like oil or water-colour paintings.
Other creations I love to work with is pot melts. Pot melts are exactly what the name suggests. Shards of glass is placed inside a pot that has a hole in the bottom. The pot is held above the kiln shelf floor via props and heated high enough and long enough for the glass to ooze out of the hole. The organic flow of colours can create beautiful designs.
All these procedures are time consuming and slow. And some knowledge of the glass you are working with is need, there are many factors needed to be considered, viscosity, devitrification, what causes it and how to prevent it, reactions of different types of glass...again, this is a rather large list. All processes involve the cleaning of glass prior to firing, the temperature and time has to be perfect, to slow or to quick can have disastrous results. Pieces often have to be 'cold worked'. And fired multiple times before it is ready for my customers.
But it is worth it, glass is a beautiful medium to work with. Best of all everything I do is completely by hand, and so even a repeated pattern, design or pot melt with be different and unique.