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Notes from the workshop: what we're casting, testing and learning.
A cast concrete surface is finished by the mould it was cast against. What the mould face prints onto the concrete, why release agent and sharp corners matter, and why a repair is only judged once it's dry.
Concrete cladding tiles bond to a wall with exterior-rated adhesive, the same way brick slips do. When we add a screw fix through the cast corner holes, and why a 12.5mm tile needs no steel subframe.
Does concrete cladding survive frost? What actually causes freeze-thaw damage, why a low-porosity GFRC mix resists it, and how we are testing our own panels through a UK winter.
Straight from the mould, concrete shows its full colour. Hone it and the sand comes through. Here's why, and why we now offer both finishes.
Quartz, sintered stone and concrete can look alike in a showroom. How each is made, how they cope with heat and knocks, and what happens when one gets damaged.
We seal every sample with the same product and technique as the finished piece. Why a raw sample reads paler, what sealing changes, and why the sample matches the worktop.
A ROKA piece looks finished within days of casting but keeps curing for weeks. What curing actually is, when a piece can be handled or installed, and why a new piece isn't fragile.
A superplasticiser lets a stiff, low-water concrete flow like a wet one without adding water. What it is, why not just add water, and why a thin cast worktop couldn't be made without it.
UHPC is ultra-high-performance concrete: an ultra-dense mix reaching 150–250 MPa, built for bridges and facades. What it is, why it's so strong, and why a ROKA worktop is GFRC instead.
GFRC is glass fibre reinforced concrete: a cement and fine sand mix reinforced with alkali-resistant glass fibre instead of steel, so it casts thin. What it is, why glass, and how it differs from UHPC.
A chalky white bloom on new concrete or GFRC cladding is efflorescence: what causes it, why it's cosmetic on a dense mix, and why the colour doesn't fade in sunlight.
Fresh concrete and new repairs read darker and duller for about a week. Why water in the surface pores does that, when the true colour shows, and what sealing changes.
A ROKA worktop is cast thin and carries no steel. Why we reinforce with alkali-resistant glass fibre instead, and what that changes.
