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About "Gold decoration" 

 We here introduce briefly trivia of gold and the following items about gold to be used for decoration.



 事業内容

      
 1) What is gold?
 2) Type of gold used for decorating and its characteristics
 3) How to use liquid gold
 4) How to use gold powder
 5) About firing
 6) Instructions ( Caution and Safety) for use of liquid gold
 7) Gold impaste decoration



 事業内容

1) What is gold?
  • It is a metal element, chemically very suitable, which resists air or sulfur (not oxidized nor dexidized and shows no change)
  • It is very malleable and easy to be rolled. One gram of gold can be drawn to approx.3,000 meter long of wire, or can be rolled to 0.5 u
2) Type of gold used for decorating and its characteristics
  • Liquid gold (called "MIZUKIN" in Japanese)
    Gold is dissolved into aqua regia ( mixed solution of hydrochloric acid/nitric acid = 3/1), and chloride gold acid, orange colored, is processed, and adding adhesive (dismuth), surfacer (rhodium), etc. the gold liquid is produced.
    • Bright Gold
      It is compound of gold and resin, but does not contain gold powder. As there is no material included to precipitate, it is not necessary to mix the solution and the finish is glossy without polishing.
    • Matt Gold
      Gold powder is added to the compound of gold and resin. The gold color tone is adjusted by adding the silver powder. (Black matt gold is made by adding blackish gold powder and its particles are finer than the ordinary matt gold. As the gold powder precipitates, you must stir well the solution, otherwise you tend to apply just top layer and it will glitter likewise bright gold.
    • Half Matt Gold
      It contains gold powder nearly half of matt gold. As the gold content is lower than that of matt gold, it will give matt type glow without polishing after firing. It will give better glow with light polishing, but you should be careful not to polish too much, as the gold surface may come off.
    • Flake Type Matt Gold
      It is made by adding gold foils ground to flake shape (scale-like shape). As the gold flakes reflect themselves brilliantly, elegant matt gold color appear without polishing after firing. It may suit to the gold decoration for the special shaped products whose it is difficult to polish. As it is not needed to polish, it is made rather hard and sticky than normal matt gold to avoid uneven coating. Depending upon the shape of the products or the area to be applied, it is better to be used by deluting with quick dry type or slow dry type of thinning oil.

  • Gold powder
    It is literally gold in powder condition, and there are following two methods to make it; 
    • Chemical Treatment (General type of gold powder)
    • Gold nugget is first dissolved by mixing with acid and resin, and then after it is chemically deoxidized, the fine particles of gold precipitate. After that, the gold powder is extracted through a filter.  
    • Physical Treatment (Flake type of gold powder)
    • In a bowl, gold foil is ground down with resin and solvent using a mixing rod for long time to get flake shape powder, and then the powder is extracted after cleaning.
  • Gold leaf
    It is rolled gold. General thickness is 0.1 micron, but thick type of gold leafl (around 0.4 micron size that is called "ATSUBAKU"or around 0.7 micron size that is called "UWAZUMI"is better use for ceramic decoration.




3) How to use liquid gold
  • How to apply it
    Shake the bottle containing liquid gold to mix well the solution and the precipitate, and pour it into small glass or porcelain containers. Apply the liquid gold to the object by adjusting the density with gold thinner. If it is applied too thick, it may cause peeling or shrinking. If it is too thin, on the contrary, it will not give off fine gold color. Try to apply it evenly as much as possible. If it is applied after the first application is dried, the solution contained in the liquid gold of the second application may dissolve the liquid gold underneath. If there is any thin-applied surface, additional application should be given gently and softly there before the surface is dried.。
  • How to dilute it
    When it is diluted, use the thinner oil supplied from the same manufacturer if possible. (Thinner oil is made with the ingredients quite similar to the solution contained in the liquid gold.) Added thinner oil is approx. 5% of liquid gold. Mix it well when liquid gold left in the bottle becomes sticky after solution is evaporated. Do not add new liquid gold, but add thinner oil and mix well.
  • How to preserve it
    Do not return the leftover of liquid gold into the original bottle, but put it in another bottle with cap and keep it at cold and dark place after adding a little thinner oil and shaking well. Preservation in the refrigerator is not recommended as the bottle inside will be sweated with fine dewdrops due to the difference from outside temperature when liquid gold is taken out from the refrigerator and put in use. The brush is generally preserved in the slender bottle which contains small amount of thinning oil and is stopped with cloth wound brush handle. (The bush tip should not touch thinner oil. The brush will not be dried for the solution evaporated from gold thinner.)
4) How to use Gold Powder
  • Mix gold powder with a little amount of flux, dissolve it into oil (thinner oil and balsam) and apply it with a brush. When applying wide area or making gradation, spread the liquid on a sponge and apply it on porcelain surface by tapping touch. (If generation is made with liquid gold, thin area is discolored to purple tone.) Also there is another way to use gold powder; at first, apply solution flux dissolved into oil. and then dust gold powder on it using brush and steel gauge. 
5) Firing
  • After gold decoration, dry it first. Put it in a kiln after it is dried to the level it does not stick to the level it does not stick to fingers when you touch it.
  • When firing, you must keep the kiln cover open (about 2-3 cm) until the temperature goes up to 400-450 ℃ to let the oxygen in the kiln circulate well. This is because gas is discharged when the resin in the liquid gold is burnt, and the good finish can not be expected unless the gas is released.
  • To secure a good adhesion, hold the highest temperature for 5-10 minutes and cool it down slowly.
  • Firing Temperature
    • In case gold decoration is directly applied on the white porcelain:  
      Porcelain ware・New bone 750-850 degrees C Generally 800 degrees C
      Earthen ware・Bone china 700-750 degrees C If fired at too high temperature, gold film might be flawed.
    • In case gold decoration is directly applied on glass:  

      Soda Glass 550-600 degrees C
      Crystal Glass 500-530 degrees C
      Boron Silica Glass 600-680 degrees C

    • In case gold decoration is applied after firing pigment   
      When the pigments of glazing is softened, the gold is easily flawed. Therefore, the firing temperature of gold decoration should be about 50-100 degrees C lower than that of pigments. It is same for enamel ware or swelled gold decoration. Otherwise, the materials applied below might be softened due to the higher temperature, and melted gold is cooled down slowly which may cause flaw.
      When re-firing after adding gold, the temperature should be a little lower (approx. 20 degrees C). When gold is applied repeatedly 3-4 times, it might be easily peeled off. Such repeated firing is not recommended.
6) Instructions (caution and safety) for use of liquid gold
  • As solvent of liquid gold contains some harmful chemicals if inhaled too much, special attention must be paid to ventilation while working with liquid gold.
  • Be careful that contact with skin may give stimulus and cause irritation. Even after contact, it will be all right if skin is washed with soap and lot of water.
  • When it enters into the eye, please flush with plenty of water at once and receive the medical examination of the doctor as quickly as possible.
  • Mistaking, when you swallow, please receive the medical examination of the doctor as quickly as possible.
7) Gold impaste Decoration
  • This decoration is made as follows; over the porcelainsurface, the ground for solid swelling of point or relief is made, and after firing, it is decorated with liquid gold or luster.
    The materials for this swelled gold decoration are powder and kneaded paste type, and there are medium and high swelling according to firing temperature. In either case, as some thinkness is required, do not make the materials too soft by adding thinning oil. Also note that firing is fone after they are fully dried.
    • Paste Enamel
      It is easy to use as it is in paste condition beforehand by adding solvent. Place it on tile or solid plate and knead it well before using. (When it it too hard, add a little amount of enamel thinner or oil-based medium. As some hardness is necessary, do not add too much.) Firing temperature is 720-750 degrees C and re-firing after gold decoration is at 670-700 degrees C.
    • Transparent Swelling (Enamel)
      As it is powder type, Knead it a little harder with medium before use. Firing temperature is 780-820 degrees C. Re-firing after gold decoration is at under 700 degrees C. In case of adding to decorate luster, re-fire it at 750 degrees C.
    • Spread ( Width) Gold Swelling
      As it is powder type, it is kneadeda little harder with medium before using. Firing temperature is 700-750 degrees C. Re-firing after gold decoration is at approx. 670-700 degrees C.
    • Gold Under Matt /(Top) Gold Swelling
      Both are of powder type, and they are kneaded with medium before using. Over thin layer of the gold under matt, after applied evenly and dried, make a gold swelled relief, and after firing at 780-800 degrees C, apply bright gold, re-fire at 670-700 degrees C and you will get an etching style finish (KUSARASI style). As the ground of matt gold, only gold swelling can be used
  • This decoration is made as follows; over the porcelain surface, the ground of three-dimensional impasted solid like point or relief is made, and after firing, it is decorated with liquid gold or luster.
    The materials for this impasted gold decoration are powder and kneaded paste type, and there are medium and high impasted gold according to firing temperature. In either case, as some thinkness is required, do not make the materials too soft by adding thinning oil. Also note that firing must be done after they are fully dried.
    • Paste Enamel
      It is easy to use as it is in paste condition beforehand by adding solvent. Place it on tile or solid plate and knead it well before using. (When it it too hard, add a little amount of enamel thinner or oil-based medium. As some hardness is necessary, do not add too much.) Firing temperature is 720-750 degrees C and re-firing after gold decoration is at 670-700 degrees C.
    • Transparent Impaste (Enamel)
      As it is powder type, Knead it a little harder with medium before use. Firing temperature is 780-820 degrees C. Re-firing after gold decoration is at under 700 degrees C. In case of adding to decorate color pigment, re-fire it at 750 degrees C.
    • Spread ( Width) Gold Impaste
      As it is powder type, knead a little harder with medium before using. Firing temperature is 700-750 degrees C. Re-firing after gold decoration is at approx. 670-700 degrees C.
    • Gold Under Matt /(Top) Gold Impaste
      Both are of powder type, and they are kneaded with medium before using. Over thin layer of the gold under matt, after applied evenly and dried, make a gold impaste relief, and after firing at 780-800 degrees C, apply bright gold, re-fire at 670-700 degrees C and you will get an etching style finish (that is called "KUSARASHI" style). Only gold impaste can be used as the ground of matt gold.







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