Low-Silica Engineered Stone: What Changes at the Saw and Polisher

Engineered stone changed in a hurry once Australia prohibited the manufacture, supply and installation of engineered stone containing crystalline silica, a ban that took effect nationwide on 1 July 2024 after Safe Work Australia recommended it in response to a wave of silicosis cases among stone fabricators, according to Safe Work Australia's own engineered stone ban materials and the Queensland and Comcare agencies that administer the rule. That single regulatory decision reshaped a global product category almost overnight: manufacturers who sell into Australia had to reformulate or exit the market, and several of them, including Caesarstone and Cosentino, have since brought low-silica and near-silica-free surfaces to the US market as well, where the older high-silica lines are still legal but increasingly share shelf space with the new generation.

For a US fabrication shop, the practical question is not whether to stock low-silica engineered stone, it is what changes when a slab of it lands on the saw table next to a classic quartz slab that looks almost identical. This guide covers what manufacturers actually say replaced the quartz filler, what their own fabrication guides say about cutting and polishing the new material, and the one point that never changes regardless of silica percentage: every engineered surface in this category, low-silica or not, is cut and finished with diamond tooling. There is no version of engineered stone, old or new, that a standard masonry blade or a bare abrasive wheel can cut cleanly, and nothing about a lower silica number changes that.

What Actually Replaced the Quartz Filler

Classic engineered quartz earned its reputation as a silicosis hazard honestly: OSHA's own enforcement materials describe engineered stone as containing at least 93 percent silica, far higher than the silica content of most natural granite, which is why the engineered-stone fabrication trade became the focus of a dedicated OSHA inspection initiative. Low-silica products exist specifically to cut that number down, and the two manufacturers with the clearest public statements about how they did it are Caesarstone and Cosentino.

Caesarstone markets a line called Caesarstone ICON, which it describes on its own product pages as containing less than 1 percent crystalline silica, with a disclaimer that the surface may carry trace crystalline silica up to that 1 percent ceiling, verified through independent XRD and health-hazard-risk-assessment testing. Caesarstone states the surface is built from a patent-pending blend that is roughly 85 percent recycled materials, including post-industrial recycled glass, though the company does not publish the full ingredient list as it considers the exact blend proprietary.

Cosentino takes a tiered approach under its Hybriq and Hybriq+ technology for Silestone. The company states that Hybriq blends premium minerals, quartz and recycled glass, while the more advanced Hybriq+ version replaces quartz with selected premium minerals and recycled material, including glass from broken bottles and windows, to reduce the crystalline silica content further. Cosentino reports that Hybriq+ technology was independently certified by SGS Australia in 2023 as keeping the entire Silestone color portfolio under 40 percent crystalline silica, with a further tier the company calls Silestone XM carrying 10 percent or less crystalline silica, and Hybriq+ surfaces include a minimum of 20 percent recycled raw material.

The two companies are not describing the same thing when they both say "low silica." Caesarstone ICON's under-1-percent claim and Cosentino's under-40-percent Q40 tier (with a separate under-10-percent XM tier) are different numbers answering to different product lines within different brands, and other manufacturers publish their own figures for their own lines. Treat "low silica" as a label that always needs a manufacturer name and a specific line attached to it, never as a single industry-wide number, and check the slab's own documentation rather than assume every product from a brand that makes a low-silica line is automatically that formulation.

Fabricating Low-Silica Engineered Stone

Cutting: Still Diamond Tooling, No Exceptions

Nothing about a reduced silica percentage makes these surfaces softer or easier to cut with ordinary tools. They remain a resin-bonded composite filled with hard mineral content, and they are cut exclusively with diamond blades suited to engineered stone, run with a water supply, following the same basic cutting discipline as classic quartz. Caesarstone's own fabrication and installation guide instructs fabricators to perform all cutting with diamond blades suitable for the material on water-fed manual or automated equipment and to consult a distributor for the correct diamond tooling, language that applies across the brand's product range including its low-silica line.

Cosentino publishes concrete feed-rate numbers in its own professional fabrication manual for Silestone: a cutting advance rate of roughly 3 to 3.5 meters per minute for 2 cm slabs and roughly 2.5 to 3 meters per minute for 3 cm slabs, always with water supplied to the cut, on a cutting table that is solid, flat and level. Those numbers come from the manufacturer's own manual rather than a universal standard, so they should be read as Cosentino's guidance for Silestone specifically, including its Hybriq and Hybriq+ lines, rather than applied blindly to a different brand's low-silica slab.

Routing and Edge Polishing

Resin content is exactly where a resin-rich, reduced-silica surface can behave differently from classic quartz at the router and the polisher. Caesarstone's fabrication guide notes that its material contains roughly 7 percent polymer resin and states plainly that the surface cannot be dry polished because it will burn; the guide calls for water-cooled diamond pads only, a progression from coarser to finer grit where each stage removes the marks of the stage before it, and polishing every visible edge to match the field finish. The same guide specifically instructs fabricators not to polish the top surface at a seam, only the edge detail around it.

Cosentino's professional manual for Silestone specifies a water-fed polishing sequence using diamond resin abrasive discs through a grit progression of 50, 100, 200, 400, 800 and 1500, with the polishing machine run under roughly 4,000 rpm. As with the cutting feed rates, this sequence is Cosentino's own published guidance for Silestone, and a shop running a different manufacturer's low-silica slab should pull that maker's fabrication guide rather than assume the grit steps and speeds transfer directly, since bond hardness and resin content are brand-specific even among surfaces that all call themselves low-silica.

*Caesarstone's own disclaimer allows up to 1 percent trace crystalline silica even on the "crystalline-silica free" claim, so read that asterisk before repeating the marketing line to a customer.

Advanced Shop Tips: Dust Is Still the Job

The single most important thing a shop owner needs to hear about low-silica engineered stone is what Safe Work Australia said when it recommended the outright ban rather than a lower exposure limit: its expert review found no evidence that low-silica engineered stone is safe to work with, a conclusion that weighed heavily in the decision to prohibit the material category rather than simply tighten the rules around it. That finding does not mean low-silica surfaces are as dangerous as the high-silica lines they replace, but it does mean a shop cannot treat a lower silica percentage as a reason to relax dust control.

In the United States, OSHA's respirable crystalline silica standard keeps applying in full regardless of which tier of engineered stone is on the saw: the permissible exposure limit is 50 micrograms per cubic meter as an 8-hour time-weighted average, with an action level of 25 micrograms per cubic meter that triggers additional monitoring and medical surveillance obligations. OSHA launched a dedicated Respirable Crystalline Silica Focused Inspection Initiative aimed at the engineered stone fabrication and installation trade in September 2023, targeting the cut stone and stone product manufacturing industry code specifically, and reported issuing violations in the large majority of the inspections it completed in the initiative's first year.

California went further and faster than the federal standard. Cal/OSHA's Standards Board approved an emergency temporary standard for engineered stone fabrication that took effect December 29, 2023, which the board later voted to make permanent; the rule effectively requires wet cutting methods without a dry exception for engineered stone containing 0.1 percent or more crystalline silica, and for natural stone containing 10 percent or more, along with air monitoring to confirm respirable crystalline silica levels against the same 25 microgram action level used federally. A shop running low-silica Caesarstone ICON material at under 1 percent silica is still above California's 0.1 percent trigger and still falls under the wet-cutting requirement.

The shop-floor takeaway is simple even if the regulatory landscape is not: run the same wet-cutting, water-fed polishing, local exhaust ventilation and respiratory protection program on a low-silica slab that the shop already runs on a classic 90-plus-percent-silica slab. A lower silica number is a genuine health improvement over the material it replaces, but it is a reduction in risk, not an elimination of it, and the resin dust, mineral filler dust and any residual crystalline silica in these surfaces all still need to be captured rather than breathed.

Maintenance and Long-Term Shop Considerations

Both Caesarstone and Cosentino market their surfaces, low-silica lines included, as non-porous and not requiring a penetrating sealer the way natural stone does; that claim comes from the manufacturers themselves and should be passed on to customers as the manufacturer's position rather than restated as an independently verified lab result. Routine care still follows the standard engineered-stone playbook: pH-neutral cleaners, trivets under hot pans regardless of brand claims about heat resistance, and prompt cleanup of pigmented liquids on a freshly fabricated edge before the surface has fully cured.

Chip and crack repair on these surfaces should use the specific manufacturer's own repair kit and color-matched resin rather than a generic stone-repair product, because the resin and filler blend in a low-silica line is not the same recipe as the classic quartz line from the same brand, let alone a competitor's line. Keep a small stock of the maker's approved repair materials for any low-silica brand the shop fabricates regularly, the same way the shop already stocks brand-specific adhesive for seaming.

Seaming follows the same manufacturer-approved logic. Caesarstone's guide calls for a color-matched adhesive system and explicitly tells fabricators not to polish a seam the way they would polish an edge; Cosentino's manual for Silestone likewise calls for a color-matched adhesive at the joint, with silicone or a colored jointing compound where a visible gap needs filling. Both systems are brand-specific, and running one manufacturer's adhesive on another manufacturer's slab is a warranty problem waiting to happen, regardless of how similar the two slabs look in the yard.

Shops that now carry both classic and low-silica engineered stone on the same floor should treat inventory control as a safety control, not just a stock-keeping task. A slab that looks identical to the one next to it can carry a very different silica percentage on its SDS, which changes the exposure assessment, the required controls and the paperwork an inspector will ask for. Label bins by product line, not just by color name, and train the crew to check the SDS before assuming a new delivery fabricates the same way as last month's slab from the same supplier.

For the broader picture of how engineered quartz fabricates versus the sintered surfaces it is often confused with, see the shop guide to quartz vs. sintered stone fabrication differences, and for the resin-burn failure mode that shows up on any engineered surface worked dry, see fabricating engineered quartz without resin burn. A bridge saw blade built for this material family is stocked as the Alpha Silencer III engineered stone bridge saw blade.