CITRIC ACID (구연산)
작업실에서 친환경으로 작업하려면 스파렉스로 대체하라-물과 구연산비율 3대1.너무 약해보이면 구연산을 더 첨가하라.구연산은 Mountainroseherbs에서 구매 할 수 있다.
염화제이철은 동에서 아주 천천히 작용하기 때문에, 나는 구연산을 약간 첨가한다.
구연산은 동을 먹어들어가는 속도를 높혀주고,추가로 가장자리의 홈 안쪽으로 침전물이 형성되는 것을 방지한다.
염화제이철과 구연산의 혼합물은 'Edinburgh Etch'라고 알려져 있다.
사용되는 염화제이철의 농도는 40%이다.
구연산 결정이나 분말은 약국에서나, 식품공업을 위한 화공상에서 구매가능하다.구연산은 주변 환경으로부터 수분을 흡수하여 혼합물이 되는 것을 방지하기위해 밀폐된 플라스틱 용기에 저장해야한다.Edinburgh Etch를 준비하려면, 나는 미지근한 물을 용기에 채우고 구연산을 첨가하며 계속하여 저어준다(물과 결정체 2대1).염화제이철에 넣을 때에 보안경을 착용한다.
The following step is important:
Before placing your copper plate in the Edinburgh Etch, the 'Sting must be taken out of it', to prevent uncontrolled biting. This can be done by placing a small copper blank in the bath and waiting until this has been completely dissolved. Or, when the mordant has been exhausted, you may use a small amount of this exhausted solution and add it to the fresh mix to take the sting out of it.
When the Edinburgh turns very dark brown and acquires a less liquid consistency, this indicates that the solution should be refreshed.
I have made use of the recipy for Edinburgh Etch as described by Keith Howard who has figured out the actual quantities to use. He gives the following example: 6 litres saturated ferric chloride + 1.2 litres water and 400 grams citric acid dissolved in water.
I took a workshop with Barbara Seidenath on electro-etching, using a saturated salt solution. While it's a bit difficult to get everything set up, I love that there's no use of chemicals, only salt and batteries. Although the solution doesn't etch silver, you can etch copper, brass, bronze, steel... I etched a large piece of brass and then used it to rollerprint on silver and copper for beautifully textured pieces, deep enough for champlevé.
Etching for Copper:
Ferric Chloride is inexpensive and is available from Chemical Companies straight from the bottle. It can also be mixed from crystals: 13 oz. of ferric chloride crystals to 16oz. of water.
Ferric Chloride will etch copper but not silver. A mustard residue is left on the surface of copper when etching with ferric chloride and it should always be neutralized and scrubbed off the metal with ammonia or ammonia and water after etching.
Metal: Traditionally, l4 or 16 gauge metal is used to etch a piece for enameling, especially a large piece because the heavier metal will still have structural strength, even after it is etched. If you want to have plenty of room to inlay color, you should plan to etch about halfway through the metal, but this isn't always necessary. On large vessel forms use 14 or 16 gauge metal, but on smaller jewelry pieces, especially if they are formed, 18 - 20 gauge metal work well, depending on the function of the piece.
Etching for Silver:
Ferric Nitrate is the acid used for etching silver. It etches cleanly and works well with oil based paint pens and heat transfer paper. It will also etch copper, but Ferric Chloride is much less expensive and lasts longer. Ferric Nitrate is basically nitric acid, which contains iron and it is neutralized with baking soda.
Recipe: 500 grams of Ferric Nitrate crystals are mixed with 1 pint of hot water until they dissolve - If you are using an etching machine - 3136 grams to a gallon of water.