Molding
Molding is the reproduction of physical objects with the help of liquid, but soon solidifying substances ( casting ) or malleable solid materials ( impression ). According to DIN 8580 manufacturing processes, molding belongs to the group of original molding processes .
use
Molding is used for reproduction of originals , for example in archeology and restoration , for the production of works of art from a master mold, the model in the art casting , the copying of originals in the criminology for forensics and in medicine, for example for the production of dentures .
technology
The first mold of the object results in the matrix , and only when you take a cast of it again, you get a body that (completely) resembles the original. The matrix can be made by casting or molding.
Creation of the form
There are very different techniques for creating the shape:
- If the original is allowed to be destroyed ( lost form ) and if it is combustible, it is attached to a conical piece (such as wood or wax) in a casting box, which will later form the casting funnel, and it is fixed with strong wires - or waxed cords, which later Form ventilation channels -, and fill the box with a solidifying mass (plaster of paris, silicone). After hardening, the piece is annealed in order to destroy the original and possibly also the funnel and fixation, deashed and poured in the desired process.
- Objects that must not be destroyed can be copied in wax and then lost.
- In general, however, multi-part matrices are produced by avoiding undercuts or by using a sufficiently elastic molding compound. When put together, the individual parts result in a usable matrix if an exact and stable fit has been ensured beforehand using registration marks . In this case, the cast shows fine imperfections in the places where the parts of the die collided ( casting seam ), which are weaker the more carefully the dies are made.
- In medicine, the molding process must be physiologically compatible.
Impression material
Until around 1900, plaster of paris (see also plaster casts ), clay , fine sand or triples (especially for metal foundries), glass , sulfur , sealing wax , alum , saltpeter , metal alloys , gutta-percha , wax , shellac , bread crumbs were most often used for casts , Glue and isinglass solution , metal foil , tissue paper and the like. Modern medical technology knows silicones , latex , alginate and polyether , which enable flexible impression forms.
Copy and original
In artificial casting , the casting seams and the approach of the casting funnel are removed or, depending on the artistic intention, they are left in order to rule out any possibility of damage or to allow the creation of the work to flow into it ( work trace ) - just as when molding valuable originals to reproduce the original differentiate and document the molding process. Removing the casting seams would mean bringing the cast close to a forgery .
Examples
In the second half of the 19th century , a large number of plaster casts of works of art were made for museums and private individuals. At that time , the Germanisches Nationalmuseum had more casts than original sculptures. However, one must by no means assume that such casts always represent the original 1: 1; Röding was able to use the Hildesheim choir screen to show that strong deviations can occur if such a complex work can be "better" integrated into the museum context.
See also
literature
- G. Spur, Th. Stöferle: Handbook of manufacturing technology. Volume 1 archetypes . Carl Hanser Verlag, Munich Vienna 1981
Individual evidence
- ↑ Impression materials in medicine. (doc) (No longer available online.) Formerly in the original ; Retrieved October 3, 2013 . ( Page no longer available , search in web archives )
- ↑ Christine Rödling, The museum production of the Hildesheim choir screen . In: Anzeiger des Germanisches Nationalmuseums 2000, pp. 145–157.