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Investment Casting Platinum Alloys

Quenching: Many casters will quench the flasks in water 10 to 20 minutes after casting. Great care should be used when quenching because the higher temperature flasks can generate steam and scalding hot water causing burns when put in water. Some casters prefer to wait until the flasks are a dull red color, hold them with tongs and use a hammer to knock the castings and investment out of the flasks by hitting the open ends of the invested flask, then quenching the investment covered castings in water. The platinum investment after burn out will resemble a fused concrete that is very hard and tenacious. It will take a lot of work to remove the majority of the investment from the castings by hammering and using a high pressure water gun or grit blasting.

Investment removal: The residual investment on the casting can be removed chemically by putting in a de-vesting solution consisting of 1 part Hydrofluoric acid to 3 parts water put in a covered, acid resistant plastic container. Be sure to read all the health and safety warnings before using Hydrofluoric acid as this is a very dangerous chemical. Proper eye protection and heavy acid resistant rubber gloves must be worn when using dangerous chemicals. Recently, some proprietary caustic alkaline de-vesting solutions have come on the market such as "J- Break" (Romanoff) that is put in a covered stainless steel pan and used hot. The hot caustic de-vesting solutions will remove the investment in 20 to 30 minutes. A homemade caustic de-vesting solution can be made using the following formulas;

Use Equal portions of the following liquid chemicals if available from a Chemical Supplier in liquid form.

Mix Equal Amounts of the Liquid Chemicals

- or -

Mix the Dry Chemicals and Water

Heavy chemical resistant rubber gloves and safety glasses must be worn when handling strong caustic chemicals, contact with the skin will cause severe burns. A large covered stainless steel pot is used to hold the caustic solution and a hot plate is needed to keep the solution hot ( 180 deg, F). A stainless steel mesh basket with a handle (French fry basket) can be used to hold the castings during de-vesting. When mixing the 50% Sodium & Potassium Hydroxide solutions, equal portions of each liquid chemical are put in the stainless steel pot and used hot. When mixing the dry Sodium and Potassium Hydroxide with water, slowly add the dry chemicals to the water in the stainless steel pot. When the dry chemicals are added to the water, a large amount of heat will be created, carefully stir the solution until mixed with a large stainless steel spoon. The heated caustic solution will take about 20 to 30 minutes to remove the investment. Do not use aluminum pots or utensils with caustic solutions. The castings should be well rinsed after de-vesting. When the solution slows down it should be replaced. To dispose of the caustic solution mix it with hydrochloric acid to adjust the pH to 7, filter the solution before disposal. The waste liquid will be sodium and potassium chlorides, salt water.

Precious Metal Spot Prices

  Bid Change
Gold $1,245.18 +$0.62/+0.05%
Silver $16.57 +$0.27/+1.65%
Platinum $917.00 +$2.50/+0.27%
Palladium $864.00 +$1.50/+0.17%
Gold 2017-06-27 1:09 AM
Bid/Ask $1,245.18/$1,245.63
High/Low $1,245.90/$1,241.10
Change +$0.62/+0.05%
Silver 2017-06-27 1:09 AM
Bid/Ask $16.57/$16.61
High/Low $16.63/$16.51
Change +$0.27/+1.65%
Platinum 2017-06-27 1:09 AM
Bid/Ask $917.00/$923.00
High/Low $924.00/$914.00
Change +$2.50/+0.27%
Palladium 2017-06-27 1:09 AM
Bid/Ask $864.00/$875.00
High/Low $875.00/$862.00
Change +$1.50/+0.17%

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Prices shown are for reference only. Please contact our trading desk for accurate, up-to-the-minute pricing.