How to make a cast of decorative masonry ?

[Axel]

Hi all,

I live in a semi-detached house built 1897. There is a decorative masonry moulding in the entrance porch that has been half broken away by a previous secondary outer door. My plan is to make a copy of the intact one on the neighbour's house. What is the best way to make a cast, bearing in mind that I can't have shuttering / supports blocking the neighbour's doorway for too long!?

Untitled

• Axel
• 22 May 2012
• 1

Untitled

• Axel
• 22 May 2012
• 1

 

[TicklyT]

How about using liquid latex, somrthing like http://www.propbuilder.co.uk/howto/mouldandcastsolid.html ?

 

[gregers]

smear it with vaseline 1st then do as tickly has said.

 

[Axel]

Might have to try and make a cast with air drying clay so I can make a quick impression...

 

[JohnD]

clay will not work if there are undercut features, or if the part was made up with several mouldings fixed together.

It will only work if the squeeze can be pulled straight off

 

[theoldun]

Firstly the two castings shown have different profiles and are not the same.
Secondly there are undercuts on that cast and you will not be able to run a mould of any sense.
Thirdly, an old school bricklayer or plasterer should be able to run that cast freehand with ultra rapid hardening cement small piece of thin ally and few stainless steel screws.
Regards oldun

 

[Axel]

There is an 'identical' pattern elsewhere on the house, but I see what you mean about the undercut.

Might have to go down the cemetary and exhume a late nineteenth century builder!

 

[Norcon]

3d laser scanner and load the data into a 5 axis cnc machine center to cut the new mould.
Simples.

 

[Axel]

I was able to bring the dead Victorian builder back to life using the HT coil from an old TV set, but he had no idea what a laser was.