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