FYI and questions about Overglazes


How are the flakes of gold dispersed within the liquid gold? Is the distribution of flakes even?

The liquid gold has two kinds of bright and matte. A gold and the element as other additive agents is contained in bright gold in the form where it reacted to resin (resinate). Except in special cases, it is a liquid which does not contain gold powder or the powder of frit at all (powder-free) . Therefore I can maintain a very stable dispersion state. On the other hand, with mat gold, in order to control gloss, gold powder of big specific gravity is blended so much. Therefore, it is comparatively easy to precipitate, so please, agitate well before an application.

What is the best way to apply it?

Liquid gold can be applied by brushing, dipping, spraying, or spin coater. (We have not yet the experience but we think that we can it even for a dispenser or ink-jet if we adjust some liquid.) Paste can be directly screen-printed to a base material. With special-use paste, pad printing is also possible. As an indirect method, printing on a paper for decal is also possible. Because of the use of resin that is combustible at a low temperature, be sure to dry lower than 150℃ and for only around 15 minutes. When the temperature gets too high, or when there is a sudden increase in temperature, cracks can appear in the film.

What is the normal thickness of liquid gold or paste gold after it has been fired.

From our estimates using Nagoya University's ultra-high voltage electron microscope, liquid gold has a thickness of roughly 0.1 microns(100nm), and paste has a thickness of roughly 0.2 microns(200nm).

About environment at the time of the application of the liquid, please teach the point where you must be careful about.

The film on a fired good is extremely thin, so after firing even wiping the applied area with lint or similar type of cloth can cause holes or cracks. Because of this, in order to maintain a high quality, please, apply the liquid gold in the area that is as clean as possible, with no trash or dust. Please be aware of the not only the tools being used, but also any loose hairs or stray paper that cloud be lying around.
A clean room is ideal, but in distances when that is not possible because of expenses, portioning an area of one room and wiping down the area with a damp cloth is very simple and effective. The method that we suggest the most is to apply the liquid gold on a mesh belt at the opening of the kiln, so once you have done the application, you can directly place it into the kiln. By doing this, you decrease the chance of dust getting onto the item, as well as decrease transport time and lead time, increasing both quality and efficiency, which in turn reduces cost. Because pottery is an insulated item, there will inevitably be some static electricity, especially in dry climates or in winter. To prevent too much build-up, use a humidifier or a grounding apparatus. Sometimes there is dust or make-up remnants in the base materials themselves, which can cause the liquid to burst or can cause cracks to appear after firing, so please check the cleanliness of the base materials as well.

What are some things to bear in mind in regards to firing kilns?

Keeping in mind the following four points: 1) Temperature rise curve 2) Atmosphere in the furnace 3) The maximum temperature and the retention time 4) The cleaning of a burning furnace and the jig 1) It is best for your kiln to reach its maximum temperature within 60 minutes. However, this is best for only single-level kilns, because multi-level kilns do not heat at the same rate, so more time is necessary. You should check the position and time and temperature by traveling. When heating rate is so fast  Case 1:As a resin suddenly burns explosively, a pattern collapses  Case 2:As a resin component does not completely burn itself out, carbon remains behind and may become poor in color development. 2) If the exhaust from chimney is insufficient, the resin, solvent, or plasticizer could combust due to a lack of oxygen, leaving carbon particles which could stick to the pottery and cause damage. Please be care of sufficient ventilation to prevent this from happening. 3) Please confirm the maximum temperature of your kiln. In order to control of the kiln temperature, please get a measurement as close to firing as possible. It is ideal to measure the maximum temperature by two separate point: when the maximum temperature is initially reached and when it has fallen. If the maximum temperature is sufficient, or the retention time is too short, the coloring may not be enough, and the adhesive strength will decrease. Conversely, if the maximum temperature is too high or retained for too long, the color could fade and the gold could become tinged with red and cracks could appear. 4) Even inside the firing, the scales of the metal jig, roller, mesh belt, and wear debris float around inside the kiln and can stick to the pottery or to the gold. In order to prevent this, clean out the firing jig with an air-blower, and occasionally remove the scale from it by polishing it, and if you have used the same one for a long time, be sure to replace it. To reduce the generating of a scale itself, replace it with high quality stainless steel, or replace with a higher heat resistance metal of some sort. It is recommended to remove the scale of the mesh belt and clean it periodically as well. Furthermore, metal scales and wear debris can pile up within the kiln itself, so be sure to clean inside the kiln periodically.

Which is suitable, gas and electricity in order to fire liquid gold and gold paste?

Although it seems that gas is cheap in fuel consumption, I think that priority should be given to decreasing a poor number as much as possible since most of manufacturing expenses, such as white body cost, decal-paper cost, and decorating expense, are spent on the work. Because I used electric direct heating and the metal firing jig, the value that was better than gas appeared and has been surprised at the heat adjustment. I think that the electricity that temperature control and the control of the atmosphere in the furnace are easy is better when I think from the point.