Questionhello Sir, yes i meant black color of gold. in the same way that is purple or green gold. are there any alloys where you need to add in order to get black color. i know nothing. i just got a request from my customer about black gold. they know nothing even i dont. its not about black hills gold but black color of gold. please let me know.
AnswerBhupesh,
there is a process that is widely used in India that is called Niello, it is a mercury based process used to give contrast against a high karat gold background. Perhaps that is what the customer is speaking about. It is highly dangerous though and without experience I don't recommend trying it unless you can set up outdoors - the process itself isn't that hard, just that the elements themselves are dealy if used improperly or inhaled- it would depend on the level of experience you qualify yourself as having as to wether or not to procedd inits lenghty expalination.
As for a coloured gold alloy formula ther are a few new on the market "chocolate" and brown colourations that are vapour deposited" and proprietary formulas.They wil eventually wear off. But to colour gold black the standard formula is:
platinum chloride in alcohol or more readily available, liver of sulphur painted hot onto the surface. Iodine will also work but you will have to make some sample tiles to get between the blue range and black colouration desired.All must be sealed with beeswax or light oil rubbed into the surface colorant. Permanance depends on the piece and the person wearing it's body chemichals, perfumes, cosmetics, etc.
There is another formula but it too is quite toxic and without knowing what you are doing can be dealdly. Disposal of the remaining solution is also an issue - as it must be properly sealed and neutralized and is more of a hassle than the job will bring you in cost and labour and acquiring the chemicals if you don't have them on hand: Nonetheless, this formula can be applied to copper, silver, brasses, in addition to gold:
120.0 g Sodium thiosulphate
Lead acetate 12.5 g
Distilled water 0.5 liters
you would mix that and store it ina non metallic lidded vessel such as glass with a ground glass stopper to store.Immediately before use, add 1.5 g citric acid- which renders the whole batch spent. So to use a portion you would then calculate how much area you want to cover and divide the stored solution adding the percentage of the 1.5 grams of citric acid necessary for the reaction to colour your piece..Remember to sela the colourant on with beeswax, oil or microcrystalline wax rubbed in well and insure that after sealing you have thouroughly rinsed the item and cleaned the parts that contact the skin as the lead content is very absorbable through the skin.
I really don't recommend your using it but that is the standard formula anyway and I understand that some customers don't care about the risks you take in making it or the risk involved in wearing it..So use your best judegment in responding to your customer and charge an appropriate fee that covers the sheer hassle and time it takes to assemble ingredients you may not have, asking and waiting for an answer through this service, and the time it takes to fabricate and colour the item- all part of the total including your shop's overhead and expenses and ordering in supplies, etc...
I hope this answers your question.
Best regards, Ari
