Many variables determine slab quality in quartz surface production: the particle size distribution of the raw material, resin content, vacuum and vibration settings, curing temperature… One of the least discussed, yet one that most directly affects line efficiency, is the release agent. A poorly chosen or poorly applied release agent comes back as sticking slabs, marks and residue on the surface, prematurely worn moulds and frequent cleaning stops.
What does the release agent do on a quartz line?
Quartz and engineered stone slabs are produced by compacting a mix of quartz, resin and pigments in moulds by vacuum vibro-compression and curing it with heat. The release agent forms a thin separating film between the mix and the mould and carrier surfaces. This film ensures clean release after curing, protects mould life by preventing permanent contact between the mould surface and the resin, and keeps the slab surface smooth.
5 criteria for the right choice
- Compatibility with the resin system: The release agent must not affect the curing of the resin or leave any unwanted effect on the surface after curing.
- Resistance to curing temperature: The film must remain effective at the temperatures on your line during curing.
- Mould and carrier material: Behaviour differs on rubber, paper and metal surfaces; the product should be chosen for that surface.
- Application method: Spray, brush or automatic application systems must suit the product’s viscosity and film-forming behaviour.
- Film thickness and consumption: The goal is clean release with the thinnest, most even film possible. Too much product raises cost and the risk of marks on the surface.
Common mistakes on the line
- Increasing the dose instead of changing the product when problems appear
- Not cleaning mould and carrier surfaces sufficiently before application
- Moving a product that worked in the lab into serial use without a line trial
- Not tracking a release agent change against measurable criteria such as consumption, ease of release and surface quality
How should a trial be planned?
The soundest way to switch to a new release agent is a line trial with success criteria defined at the outset. Before the trial, resin type, mould/carrier material, curing conditions, the current product and its consumption are clarified. During the trial, ease of release, slab surface, mould condition and consumption are recorded and compared with the current product.
From Biyopol Kimya: We supply process-specific liquid release agents to quartz and engineered stone producers and run trials on your line with samples. See our Quartz and Engineered Stone page for details.