Self Curing and Heat Curing Systems
The audacryl materials have been successfully used for over 25 years by hearing device manufacturers as the basis of their solid earmould and shells. This acrylic system comprises of a powder and liquid matched pair, carefully engineered for the application, and adapted for both self cure ( RTC) and heat cure curing ( HC) ,these powders are available in many colours including a wide range of skin tones.
Audacryl RTC Self Curing System
Cured in gel or plaster, usually in a pressure pot, 30 psi, under water for 30 minutes. Typical mix is 2 parts powder to 1 part liquid. Material is usually poured into the negative.
For crystal clear moulds use powder Z650 0039 & liquid Z871 0000.
For transparent shades use liquid Z871 0000 or tinted liquids with clear powder.
For opaque colours use liquid Z907 0000 with opaque shaded powders.
Audacryl HC heat curing system
Cured in plaster, under pressure, usually in water bath. Cure time approx 1.5 hours. Typical mix is 3 parts powder to 1 part liquid, material is packed as dough. For all heat cure powders use liquid Z909 0000.
The effect of using a more fluid mixture in these systems, ie. more liquid in the mix ( temperature being equal), is that the cure time will be extended, the colour diluted, and shrinkage increased. The residual monomer in the cured piece may be higher unless the cure time has been adjusted to compensate.
When using plaster, several coats of a good separator should be used. The acrylics are finished with standard steel and other burs and polishing compounds. For the self curing resins, wait until the mix has dulled over or skinned over before placing into pressure vessel. The liquids can be tinted with colour concentrates available from Esschem Europe. Tinting the liquid gives a final earmould with a transparent colour tint.