The case of external shapes requires additional elements to be taken into account when compared to taking an internal shape impression.
The choice of the product is made according to the area to be controlled, its difficulty of control and also according to its external environment (orientation, accessibility, etc…).
Plastiform has developed different product consistencies : pasty, fluid or malleable. Each of them can be suitable for external impression taking, although the use of pasty or malleable plastiforms is generally recommended due to their non-flowing properties.
When the surface to be inspected does not have a complex shape that can prevent demoulding (no removal constraint), it is recommended to choose a plastiform with a semi-flexible final consistency. As the latter can be sliced by the Double Blade Cutter, their control is much easier. The P35 or the M70 are the ideal products for this type of situation.
If the constraint is too high, a most flexible products should be chosen. Some of them have been specially developed for the extraction of a complex external shape, allowing the user to extract its shape while keeping the possibility of cutting its profile. These are P25 and M25.