How to Choose HPSIL® Toothpaste Silica Gel: The Three-Grade System Explained

The procurement question

You're sourcing silica for a toothpaste formulation. The single-supplier offer is one grade called "toothpaste silica". The product datasheet lists particle size and oil absorption — but those numbers don't directly translate to the procurement metrics that matter: RDA (cleaning power), paste consistency (consumer feel), visual appearance (white opaque vs translucent gel). Why not?

Because toothpaste isn't one silica problem — it's three. Toothpaste silica is a system of three different grades doing three different jobs. Here's the breakdown.

The three silica functions in toothpaste

Function 1: Abrasive (cleans teeth)

This is the silica that physically removes plaque, stain, and tartar by mechanical contact with tooth enamel. Particles are large (5-15 μm) with controlled mechanical hardness. Loaded at 15-25% on total formulation.

The key procurement metric is RDA (Relative Dentin Abrasivity), measured per ISO 11609. RDA scale:

HPSIL® D-series grades are engineered to hit specific RDA targets:

• HPSIL® D-30 (RDA 30 ± 5) — sensitive teeth, baby toothpaste
• HPSIL® D-60 (RDA 60 ± 5) — mass-market daily
• HPSIL® D-100 (RDA 100 ± 5) — standard whitening
• HPSIL® D-150 (RDA 150 ± 10) — premium / professional whitening

Function 2: Thickener (gives paste consistency)

This is a different silica entirely. Particles are smaller (1-5 μm) with high oil absorption (110-250 ml/100g). They form a hydrogen-bonded thickener network in the wet humectant phase, building paste viscosity. Critical: zero abrasive function (low RDA <5).

HPSIL® T-series:

• HPSIL® T-100 (oil absorption 110 ml/100g) — standard opaque paste
• HPSIL® T-180 (oil absorption 180 ml/100g) — transparent gel toothpaste (RI-matched)
• HPSIL® T-250 (oil absorption 250 ml/100g) — high-viscosity premium

Function 3: Opacifier (makes paste look white)

A third silica grade, even smaller particles (0.5-2 μm), specifically optimised for light scattering. Loaded at 0.5-2.5% to control visual appearance. Distinct from abrasive (which is large enough to remove stains) and thickener (which is small enough to form network but not scatter strongly).

HPSIL® O-series:

• HPSIL® O-50 — typical opaque toothpaste
• HPSIL® O-110 — intense white visual

Why each function needs a different grade

Functional separation is non-negotiable for three reasons:

Reason 1 — Abrasivity is incompatible with thickening. A silica that's large enough (8-12 μm) to clean teeth cannot simultaneously form a tight rheology network. A silica that's small enough (1-3 μm) to thicken cannot clean — particles slide past enamel without abrading.

Reason 2 — Opacity wants a third size range. Visual scattering peaks at particle size ~0.5-1 μm (matching the wavelength of light). Both abrasive and thickener silica miss this size window.

Reason 3 — Regulatory and cost optimisation. Three grades at three different loadings let you tune cost (cheaper opacifier at 1%, premium abrasive at 18%) and regulatory profile (each grade meets specific FDA / Pharmacopoeia limits separately).

The standard whitening toothpaste recipe

Premium whitening toothpaste, RDA 100-120, opaque white visual, paste rheology suited to brush application:

The 25.5% total silica is mostly invisible to the consumer — they experience cleaning (the D-grade), paste behavior (the T-grade), and appearance (the O-grade). But each is doing distinct work.

Substituting from Evonik Sident

If your existing formulation uses Sident-series toothpaste silica, the substitution map:

1:1 substitution typically gives within ±5 RDA points (within ISO 11609 reproducibility). Run an independent RDA test on each substituted formulation before committing to production.

Transparent gel toothpaste — the special case

Transparent gel toothpaste uses only thickener silica, no abrasive. The visual is achieved by matching the refractive index of the silica (~1.45) to the humectant phase (glycerin + sorbitol + water, also ~1.45). HPSIL® T-180 is specifically engineered for this RI match.

Recipe simplification:

• HPSIL® T-180 thickener: 8-10% (higher than opaque paste because it's doing thickener AND opacifier role)
• No abrasive (D-series excluded)
• Humectant phase: glycerin + sorbitol = 50-60% (RI tuned to silica)

Cleaning function in transparent gel comes from the brush's mechanical action plus fluoride chemistry — not from silica abrasion.

Procurement and lead time

MOQ 1 pallet (1.0-1.2 t) per grade. Lead time 4-6 weeks FOB Shanghai. Container shipments can mix abrasive + thickener + opacifier grades for combined freight cost optimization. Heavy metals CoA, EU 1333/2008 E 551 compliance, FDA 21 CFR 172.480, and NMPA Cosmetic Registration documentation included with each shipment.

For new toothpaste formulation development, we recommend ordering small samples (5 kg) of HPSIL® D-60 + D-100 + T-180 + O-50 to evaluate the standard formulation matrix, then commit to commercial supply once the target RDA and consumer feel are validated.

FAQ

Why can't I just use one silica for everything?

You can, but you'll either get bad cleaning (small particle silica) or bad rheology (large particle silica) or non-uniform white visual (mid-particle silica). The three-grade approach is the industry standard for premium toothpaste.

What's the typical premium whitening toothpaste RDA?

80-150 RDA depending on positioning. Sensitive-skin whitening: 80-100. Standard whitening: 100-130. Premium whitening: 130-180. Heavy clinical whitening: 180-250 (ADA permitted maximum). Final RDA is determined by your D-series grade choice and loading.

Can HPSIL be used in EU toothpaste?

Yes. All HPSIL grades are EU Cosmetics Regulation 1223/2009 compliant and E 551 listed (silicon dioxide synthetic amorphous, no quantum satis limit). Heavy metals CoA included with each batch matches EU 1223 limits.

What about NMPA (China) registration?

All HPSIL grades are NMPA-registered for use in cosmetic toothpaste manufactured in or imported to China. Registration documentation is provided with each shipment.

What's the difference between D-series and Aerosil-grade fumed silica?

D-series is precipitated silica (wet route process). Aerosil-grade fumed silica is flame hydrolysis product. Both are amorphous SiO₂, but the precipitation route is required to get the controlled particle size (5-15 μm) and mechanical hardness profile needed for dental abrasive function. Fumed silica is too fine (7-40 nm primary particles) and lacks the abrasive function.

Related

• HPSIL® Healthcare Silica Hub — full grade lineup with food / pharma / cosmetic
• Coatings Hub Selection Guide — for HPSIL R110 cosmetic / mattifier applications