| You are technically helpless in some ways | | | | decorating kiln temperature. This may cause |
| when it comes to gelding. You are at the | | | | blistering of the gold or other problems. The |
| mercy of your gold supplier. Preparations of | | | | gold emulsion supplier can make the emulsion |
| gold emulsions used in ceramic decorating are | | | | more suitable for higher firing.So the |
| prepared in secret. Any technical problems | | | | problem is glaze control.Why do you have |
| relating to the emulsions used must be | | | | variation in the hardness of the |
| resolved by the gold vender. Also, the | | | | glaze?Remember that we are talking about |
| emulsion suppliers often adjust emulsions to | | | | fusibility here.Most fine china glazes are |
| resolve problems not caused by regularly used | | | | lead based. Lead bisilicate is a lead frit |
| emulsion formulations.Gold and other precious | | | | commonly used. It is make in large batches |
| metal emulsions are used in the ceramic | | | | and the specific gravity of each batch is |
| industry to add value to a product. This is | | | | different. Therefore the laboratory at the |
| usually in the form of banding or hand | | | | factory must calculate the lead content of a |
| painting. Banding can be by hand or by | | | | glaze made with a particular frit batch. If |
| machine. On firing, the gold must sink to the | | | | the lead content is too high, then the lead |
| proper extent. It is called soft if it easily | | | | bisilicate must be cut back. If the |
| abrades off with a pencil eraser. If it sinks | | | | calculated lead content is too low, it must |
| too far into the glaze and looses its ability | | | | be increased.The best control for the glaze |
| to be buffed to a fine polish, it is called | | | | itself is the FIRED specific gravity. Fire a |
| hard.Hard gold can be caused by soft glaze. | | | | cup of glaze, break out a chunk, and measure |
| That is the glaze is more fusible than usual. | | | | the specific gravity. Use this as a control |
| The decorating supervisor tells the lab that | | | | procedure.To maintain better control, blend |
| the glaze is soft, lowers his decorating kiln | | | | frit batches before glaze formulation to even |
| temperature, and hopes the next lot of glazed | | | | out the composition. Work with your suppliers |
| ware will not cause him more problems.Soft | | | | to standardize their materials. Blend glaze |
| gold from hard glaze causes him to raise his | | | | batches to get the right glaze hardness. |