YY 0713-2009Dental gypsum-bonded casting investments (English PDF)

2.1 Gypsum-bonded investment powder

A powder mixture consisting of silica and calcium sulfate hemihydrate and/or other refractory component.

NOTE: powders may include small amounts of modifier.

Category 3 Combined with dental plaster casting investments are classified as follows.

--- Type 1; for inlays and crowns.

--- Type 2. for full and partial denture base port.

Some of the material is not limited to this category of one type.

4.1 Appearance powder

Liquidity 4.2 hours when By 6.2 test, the cured material is at least the diameter of type 1 60mm, Type 2 at least 40mm.

4.3 Clotting time

Press the test measured 6.3 clotting time and coagulation time manufacturers should provide no greater than 20%. If the manufacturer provide for A time range, the coagulation time should the value of the intermediate time range no greater than 20%.

4.4 Compressive strength Press

Test 6.4, the compressive strength of the material of a minimum type of 2.3MPa, type 2 minimum 2.6MPa.

4.6 Linear thermal expansion coefficient

By 6.6 test, linear coefficient of thermal expansion material manufacturer should provide a value no greater than 20%. If the manufacturer provide for a range of values Wai, the measured value should be in the middle of the range of values differ by not more than 20%.

5.1 Sampling

Take the same batch sufficient retail packing material at least 5kg. In addition to sealing the packaging material should not give up.

If Bulk powder is then mixed thoroughly before testing and should be stored in a moisture-proof container.

6.1 Appearance of the powder

Test by naked eye observation, the powder should be uniform, no lumps and foreign matter.

6.5 Setting expansion

Test Press, curable plant expansion should provide a value no greater than 20%. If the manufacturer provide for a range of values, The measured value should be in the middle of the range of values differ by not more than 20%.