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Complete pre-cutting processes for opal doublets and triplets
|Unit Descriptor||This unit covers skills and knowledge to select and prepare opal and backing materials for cutting as doublets or triplets and complete all precutting processes. It includes documenting and recording all aspects of the procurement and cutting process. No licensing, legislative, regulatory or certification requirements apply to this unit at the time of endorsement.|
|1 . Select opal for cutting as an opal doublet or triplet.||
|2 . Flatten opal and base.||
|3 . Cement components together.||
|4 . Preform opal doublet.||
|5 . Convert doublet to triplet.||
|6 . Follow OHS principles when operating machinery.||
|Key Competency||Examples of Application||Performance|
|How can information be collected, analysed and organised?|
|How are ideas and information communicated within this competency?|
|How are activities planned and organised?|
|How are problem solving skills applied?|
|How are mathematical ideas and techniques used?|
|How is use of technology applied?|
|How is team work used within this competency?|
Suitable material may include:
multiple bars of colour with potch between
off-cuts from solid production
opal from unsuitable boulder iron stone
opal prone to crack (triplet only)
opalised shell skins
thin bar of colour in potch
thin seam opal
weak colour on a clear base (jelly opal).
Appropriate equipment may include:
silicon carbide grinder
Backing materials may include:
black potch (best)
boulder iron stone
clear or transparent potch
dark grey potch
glass (triplet only)
vitrolite (triplet only).
Blacking agents may include:
black epoxy additives
black permanent markers
Adhesives may include:
Loctite UV 358 or 363 (triplet top to opal)
UHU Plus 24hr (opal to backing)
other glues, such as UHU Quickset, MEGAPOXY 69, EPOXY 330, TENAX+ super glue, BOND 527, TITE ON.
Triplet top materials may include
commercial standards size triplet tops
glass, plain or plate
lead crystal glass
synthetic spinel, corundum, topaz.
General OHS principles and Safe Operating Procedures sheet may include:
complying with the safe operating procedures for each machine
using personal protection equipment where required.
Overview of assessment
Critical aspects for assessment and evidence required to demonstrate competency in this unit
To achieve competency in this unit, a person must be able to select appropriate materials for making into a doublet or triplet and complete all pre-forming processes using safe working practices.
Assessment must confirm the ability to select the materials for making into a doublet and to make decisions on how to cut the material and what the final product should be. It involves preparing the opal and the backing material, flattening the stone and backing and cementing the two together. It also involves using the same skills to make a triplet from a very thin opal layer with a transparent triplet top.
Competence in this unit must be assessed over a period of time in order to ensure consistency of performance over the range of variables and contexts applicable to the work environment.
Context of and specific resources for assessment
This unit may be assessed in a work environment, in a simulated work environment or in a combination of these situations.
Method of assessment
For valid and reliable assessment of this unit, evidence should be gathered through a range of methods to indicate consistent performance.
Assessment of this unit of competence will usually include observation of processes and procedures, oral and/or written questioning on underpinning knowledge and skills, evaluation of the final product and other methods as required.
Assessment methods should closely reflect workplace demands (e.g. literacy) and the needs of particular groups (e.g. people with disabilities, and people who may have literacy or numeracy difficulties such as speakers of languages other than English, remote communities and those with interrupted schooling).
Guidance information for assessment
Assessment of this competency requires access to:
an opal cutting workshop
a qualified workplace assessor or assessment team.
This unit may be assessed on its own or it may be assessed with other units that cover related skills and knowledge.
Evidence is most relevant when provided through an integrated activity which combines the Elements of competency for the unit, or a cluster of units of competency.