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Solutions for moulders...  

 A set of solutions for the moulders

colonne crénelée en pierre reconstituéeYou want to cast reconstituted limestone elements with particular shapes but you don't know how to build the needed moulds. Here are exposed unsorted ideas and the various possible solutions to realize various types of moulds.

  • How to cast cladding stones with irregular outlines ?
    A simple solution to build the mould consists in using boards of water-resistant agglomerate CTBH. We find easily and at low cost some CTBH agglomerate boards for floor in 1850x600 mm size and 19mm or 22mm thickness, in great do-it-yourself stores.

    A first board of 22mm thickness will be used as a rigid basis for the mould.

    In a second one, forms corresponding to a typical natural stone assembly are cut out, according to a pattern which can be reproduced ad infinitum. This second board thus cut out is simply laid on the first one for the cast of the limestone mortar.
      - If the cladding stones made are of great dimension (> 400cm2), we will take a board of 22mm thickness, if not, we will be able to take a board of 19mm thickness.
      - The edges of the cut out forms must comprise a “draft” angle of about 30%. I.e. that they must be oblique to allow the release from the mould.
      - The draft angle must be regular and continuous on all the periphery of the forms and always directed towards the same side of the cladding stone.


    How to cut out the forms?
      - You Get photographs of walls or models of the pattern which you wish to reproduce.
      - Trace a grid on the board with a paper pencil, to serve as a guide and delimitation for the stones.
      - Trace free hands the shapes of the stones in the grid, while keeping a minimal zone of approximately 25mm between the stones, for the solidity and the cohesion of the mould. - Bore a hole with a drill on each form to introduce a jigsaw.
      - Cut out each form with the jigsaw, using a relatively fine blade to authorize the “tight turns”.
      - If you can, incline the jigsaw of 30% for the draft, but take care not to break the blade.
      - Best bet, even if it is a little more tiring, is to carry out the draft angle after cutting, using a wood grater.
      - When the drafts are finished, sandpaper the whole.

    At this stage, your mould is finished.
le mouleCliquez pour voir en grandLa dépouille du moule
The final aspect of the mould, with draft detailed, for the release.
Clic on the drawing above to see it in large view.
    Before to cast the limestone mortar, grease the edges of the forms with some oil or soapy water, to facilitate the release from the mould. Pose the mould board over the base board, the narrowest side of the stones (that which will be visible on your wall) upwards. Fill the forms with mortar while overflowing slightly.

    After an adequate curing time (cf the moulder's guide) scrape the stone in excess.

    For the release from the mould, unstuck the mould board from the base and hit slightly the mould, between the stones, to unstuck the edges, stone by stone, with a small hammer.
Le démoulageLes plaquettes de parementLa finition brute aspect pierre rugueuse
The release from the mould and the rough limestone finishing aspect.
Its also possible to obtain a much smoother finishing aspect by sandpapering.

    Then apply to each stone the surface treatment which is well, according to the aspect which you wish to obtain (cf the moulder's guide).

  • This principle of mould is usable for any shape of facing and cladding stone, with regular or irregular outline.
  • Here some exemples :
      - An interior cut stone lintel of 5 elements with a key in the center, for door and window in rabbet or bracket. On only one CTBH agglomerated board of 1850x600mm, we can draw a complete lintel of more than 1,5m with 2 X 2 elements or 2 X 3 elements + the key.
      - A surrounding of reconstituted cut stone, for door in rabbet or bracket.

  • How to quickly and easily create molds for all kinds of cladding stones?

    moule polystyrène plaquettes de parementTechnique moule polystyrène découpe thermiqueStyrofoam boards 20 to 40mm thick can be cut easily with a knife or a hot-wire saw to quickly make molds for field stones or for cut stones. 

    Tools for hot-wire cutting are described on the site and plans are available, to build them quickly .

    More about the styrofoam molding and hot-wire tools

  • How to make pilasters elements for interior decoration, or large diameter columns ?   
- By using a piece of PVC pipe for for sewerage of diameter 100mm or 125mm, cut into two halves in the length direction and closed to the two ends by plates of water-resistant agglomerate.

- By using in the same manner a metal chimney pipe cut into two halves. See the solution of Eric.

- PVC tubes up to 600mm in diameter can be used to make large diameter columns. Such tubes can be found for instance in the ranges Sotralys or Sotrabat at SOTRA SEPEREF
mold for cast stone columnmold for cast stone column with two halves PVC tube

The PVC tube is cut in half lengthwise. Four wooden strips are screwed across the PVC to enable the assembly of the two elements of the mold. Place the pipe in vertical position and make a wooden frame around it to counter the concrete pressure during pouring.

  • How to realize small columns ? 
Moule PVC pour petite colonne en pierreLe Parthénon- Like for pilasters elements, to realize small columns, we can use PVC tubes (sewerage, watercourse) of diameter 100mm for instance.
See Sotra-Seperef site >>

Cut the pipe in the length direction. Close it using adhesive tape. Then you can fill in the pipe by the top with the limestone concrete.

For the realization of the pedestal and the capital of the column, you can use styrofoam plates where forms are cut using a hot-wire saw. See the pdf documents in the site for the styrofoam molding technique.

  • How to create columns cylindrical, conical or with crenellated sections?
You can make styrofoam molds, using the cardboard jigs method.. More about this method...

découpe moule polystyrène colonne pierreMoule polystyrène pour élément de colonne lisseMoule polystyrène pour élément de colonne crénelée

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