THINGS TO REMEMBER

Enamel does not melt like ice. First it contracts (sugar fire) then it expands (flow) Orange Peel is the moment at which enamel stops contracting, and is beginning to flow. You MUST reach this point in order for a molecular bond to form between the metal and the enamel. Meanwhile the copper is expanding (as it heats) and contracting (as it cools) Maintaining a balance between these two opposite actions is key to successful firing.

Counter enamel is KEY to acheiving this balance. Metal that is enameled only on one side is very likely to crack.

Every enamel has a different rate at which it fuses and flows. Therefore, it is also not always possible to layer enamels over one another if they are not compatible. Lower expansion enamels go on top of higher expansion enamels – not the reverse (fusion and flow rates are recorded on the supply site on individual colour pages).

If you don't know the fusion and flow rates of the enamels you are working with - do a test by putting a small amout of each colour that you are working with on a small piece of copper, and note which ones melt first, and which melt last. The ones that melt LAST should be in the first layer. 

FLUX refers to transparent enamel with no colour in it NOT to soldering flux.

Opaque and transparent enamels need to be worked with in different ways:

• Opaque enamel and counter enamel should generally be fired only to orange peel stage until the final firing of the piece. This is to ensure molecular bond, and minimize the danger of over-firing or burning over the course of several firings)
• In the first layer, transparent enamel and flux must be fired beyond maturity to the T-FACTOR (transparency), but ONLY in the first layer. Subsequent layers should be fired only to SUGAR consistency. This is to ensure transparency (in the first layer) and prevent overfiring or burning in subsequent layers.

If any enamel is fired only to sugar consistency in the first layer – it will be unlikely to have formed the molecular bond. Re-firing will sometimes solve the problem, but not always.

T-factor is a function of temperature and not only time. Leaving a piece in for a long time at a low temperature will never achieve transparency. The temperature varies with different colours, but it must generally be over 1450 for at least 15 seconds (i.e.: the piece must reach at least 1450 and STAY THERE for at least 15 seconds).  Sometimes hotter temperatures and longer times are necessary.

Pieces that have not achieved good transparency in the first firing can SOMETIMES be re-fired higher to clarify, but sometimes they can’t. Flux can almost always be re-fired to achieve transparency.

It is advisable, especially when making jewellery, to counter-enamel first to prevent trivet marks from firing into the front.

Be sure to get a large and stable enough trivet for your piece: a SMALL piece on a LARGE trivet is better than a large piece on a small trivet.

Remember that the kiln is hotter at the back and the sides than it is in the middle. Try to place your piece in the middle or slightly to the front so that you can see it.  You can put it to the back if you need a higher temperature, but to the front if you need less heat, or need to watch the piece closely.

I often recommend counting to 60 while the piece is in the kiln - to be aware of the time and to keep focused - but try not to get too attached to a specific time – the purpose of counting is to keep your attention focused on the kiln, not to tell you exactly when to take the piece out. There is no perfect time – you just have to pay attention.

There are hundreds of variables, and only experience will give you control over firings.

Try to pay attention to the colour of the kiln and learn how to recognize when the piece is going through the stages of fusion and expansion in the kiln.

Fusion is when the grains begin to bind together and expansion is when they begin to flow.

It takes about ¾ of the firing time for the piece to rise to the proper fusion temperature. The change from sugar consistency to maturity happens in 15-20 seconds. From sugar to orange peel is about 5-10 seconds.

Firing times are not cumulative. If a piece is fired for 1 minute, putting it in the kiln again for another 30 seconds is not equivalent to a 90 second firing.  If it is under fired at one minute, to correct this problem you will have to start again firing for a longer time and/or at a higher temperature.

The gum binder (Klyr Fire) does not assist in the fusion of the glass to the metal IN ANY WAY. It is simply there to keep the grains from being accidentally disturbed. It is therefore recommended, but not necessary.

NONE OF THESE THINGS IS ROCKET SCIENCE! BUT HOLDING THEM ALL IN YOUR HEAD WHILE YOU FIRE IS CHALLENGING. THE SOLUTION IS PRACTICE, PRACTICE, PRACTICE!