Creating The Casting Mould; Stress Relief; Protective Investment Coating; Types Of Flask - DeguDent Optivest SR Mode D'emploi

5

Creating the casting mould

5.1 Stress relief

In most cases, the wax model does not require stress relief. If the wax model has very delicate
details, wax objects may be painted or sprayed with a thin layer of wetting agent and then carefully
blown dry (do not use pressurized air). The wax surface must be absolutely dry before investing.

5.2 Protective investment coating

Before investing the wax model in Optivest SR, the wax surface can be pre-treated with a
protective investment coating to ensure that no bubbles are formed in undercuts or in complicated
areas of the casting, replicating surfaces exactly as they were on the wax model.

5.3 Types of flask

We recommend using reusable plastic or silicone flasks. These ensure an even distribution of the
investment compound around the model and a uniform distance between the base of the cast and
the outer surface of the investment. This distance should be at least 10 mm. It is important for the
stability of the muffle during the heating phase and at the same time reduces the risk of muffle
tears.

5.4 Mixing the investment compound

Measure Optivest SR and mixing liquid and mix as described in 4.2.
For mixing ratios refer to the recommended concentrations in the table following 6, Expansion
control.

5.5 Investing

Pour mixed investment compound into the muffle using slight vibration. Make sure to void trapping
air. After the casting mould has been filled, turn off the vibrator immediately.
When investing crown and bridge frameworks, it is recommended to fill the crowns with
investment first. Optivest SR is primarily an investment intended for metal casting. By contrast
with specialized crown and bridge investment compounds, the working time is relatively short.

5.6 Hardening

Allow the casting mould to harden for approximately 45 minutes. Once the investment compound
has set, slightly grind the cover of the muffle using a dry trimmer to remove the glaze layer so that
any gas can escape.

5.7 Wax elimination

Pre-heat the furnace to 250 °C and place the muffle into the furnace with its funnel facing down.
Keep the muffle in the chamber for 45–60 minutes to eliminate the wax! Make sure to keep the
chamber door closed to keep noxious gases from escaping!
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