GC EUROPE Fujivest Super - Manual (Page 8)

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- Resin modeling materials
GC Pattern Resin LS makes an excellent choice,
offering a high degree of accuracy in combination
with optimal burnout properties which leave no
residues.
It is always advisable to cover the pattern resin with
a layer of wax to allow for its expansion during the
burnout process.
For single crowns, the investing and burnout
procedures can be performed in the usual
manner, however for larger amounts of pattern
resin it is advisable to hold the temperature at
250°C (482°F) for 1 hour, before rising to the final
burn out temperature or follow the step heating
schedule according to the ‘Instructions for Use.’
The rigid nature of the pattern resin material means
that the initial setting expansion can be restricted,
which may result in a tight casting. This problem
can be solved by the adoption of a slightly higher
ratio of investment liquid/distilled water.
1.4.2 Ring sizes
The majority of GC Europe investment materials
can be utilised for both the ring and ringless
techniques, using either the quick or step heating
technique as detailed in the particular
‘Instructions for Use.’
In most instances GC Europe investments can
be used with all ring sizes from X1 to X9 for the
casting ring technique (metal ring with liner) and
sizes from X1 to X6 for the ringless technique.
The choice of ring size depends on the size and
type of work, however to get consistently accurate
casting results it is advisable to take a uniform
approach. This is best achieved by always selecting
the same size/type of investment ring for the same
size/type of work. In general terms ring sizes X3 &
X6 provide consistently accurate and reproducible
results due to the optimal volume of investment
material that is used.
When using the X1 type ring tighter castings may
be produced, this is caused by the smaller amount
of material producing a smaller setting expansion;
this is related to the exothermic reaction during
setting. Conversely ring sizes above X6 tend to
produce a less stable expansion values and an
increased risk of cracking.
1.4.3 Ring types
Various sizes and types of casting ring are available,
all created with the same goal of producing a
refractory investment mould which can be heated
to eliminate the pattern material and filled with
molten alloy.