The arris is the visual
A Georgian cill, a keystone, a quoin — the visual is the sharpness of the edge. A soft arris makes the whole piece look wrong. Silicone tooling of the right hardness holds it.
Cast stone · Dressed-stone moulds
Cast stone moulds that hold the arris pour after pour.
Silicone and polyurethane tooling for keystones, cills, quoins, string courses, finials and Georgian dressed-stone reproductions. Sharp arris on demould, clean face without the tool picking up bench dust.
When it fits
When cast stone moulding matters.
You're matching a listed elevation
A cast-stone workshop rebuilding a lost cill or a broken keystone needs a mould that reproduces the original geometry exactly. Send us the sample, we'll rebuild the mould.
It's a repeatable line of dressed pieces
Cill runs, quoin runs, string courses. The same shape repeated dozens of times. The tool has to demould cleanly every time, or the line stops.
Face texture has to be even
Cast stone often has a specific face texture — light broach, fine rubbed, honed. The mould has to release without picking up the texture and dulling it over the run.
The choice
How we spec a cast-stone mould.
For cast-stone work we lean towards silicone with a firmer shore hardness than we'd use on a heritage silicone insert. The trade-off is deliberate: firmer silicone holds the arris longer, at the cost of being slightly less forgiving on complex undercuts. On most cast-stone pieces the geometry is straightforward enough that a firmer silicone is the right call.
For simple repeating pieces — long cill runs, straight string courses — polyurethane may be the more economical answer, especially where you're running the same shape for months at a time.
The mould is always two-part or three-part on cast-stone pieces, with the split line planned so the parting mark falls where the finished piece won't be inspected closely. On a Georgian cill that's usually the back or the underside. On a keystone it's the return, not the face.
What we need
To quote this properly.
A drawing or a rubbing
A dimensioned drawing is ideal. A pencil rubbing of the original moulding profile is also useful, especially for listed replication.
A photograph of the finished face texture
Rubbed, honed, broached, tooled. Determines the release regime the mould is built around.
Weekly piece count
A run of two hundred cills a month is a different tool from twelve keystones a year.
Whether the piece is reinforced
Rebar in a cast-stone piece changes how the mould is filled and demoulded.
The honest bit
Cast stone rewards patience at the pattern stage.
The pattern is where the mould's success is decided. A pattern that's not quite square, or that has a soft arris to start with, produces a mould that will never quite give you what you want. We spend proper time on the pattern before we pour the silicone against it.
For heritage replication, we often ask you to send us the surviving section of the original so we can pattern from it directly. It's the fastest route to a mould that reproduces the shape faithfully, and it avoids a round of interpretation drawings.
Cast-stone moulds on a hot pour will thermally cycle. Over a long run that will slowly relax the silicone. We spec silicones rated for the peak temperature you're running, and we tell you when to expect the tool to need replacement based on the pour count and the mix.
Drill down
3 variants of this service.
Each one has its own page with the detail we'd normally cover on the first call.
Related
Where this fits in the wider system.
At a glance
The ideas in pictures.
How a two-part mould fits together
Swipe to see the whole diagram
From sample to finished cast
- 01Sample, drawing or scanWhat the finish must match
- 02Master patternCarved, machined or taken from the original
- 03Liner or mouldMade in the right elastomer
- 04Trial castChecked with your mix
- 05Production castsLiner reused across the run
- 06Kept on fileReady for repeats
Swipe to see the whole diagram
Get in touch
Send us a photograph of the panel or the elevation.
One photograph tells us what surface you're chasing, and one line about the mix tells us what silicone or polyurethane will survive it.
Real people, a real workshop
You deal with the people who make it.
No call centre and no middlemen. When you contact TCI Construction, you speak to the team who design, build and check your mould.
- A real Warwickshire workshopUnit 15, Waterloo Park, Bidford-on-Avon, Alcester B50 4JG.
- Real people on the phoneCall the team on 01789 224228, Monday to Friday.
- The same team on every jobDesign, production and aftercare come from the people you see here.
- Part of TCI GroupFive specialist brands, one engineering team. Visit TCI Group.
Thomas LaneManaging Director
George PrestonDesign & Project Manager
Kelly BallingerHead of Partnerships
Jim AndertonProduction Manager
TheodoreEmployee Welfare