Frequently asked questions

52 questions our application engineers get asked about CENSIL functional silica — which grade, at what dosage, under which regulation — sorted by the nine application tracks. Every answer points back to a grade and a test you can run in your own plant.

01Feed additives 02Food powders 03Oral care 04Agrochemical 05Industrial fluoride removal 06Coatings 07Defoamers 08Film antiblock 09Masterbatch —Ordering & supply
Track 01 · Feed additives

Feed Additive Flow & Carrier

Grades: CENSIL 260P · CENSIL 265P · CENSIL 280P

Solution page →
It depends on the liquid load. CENSIL 260P is the base carrier for moderate loads where flow and caking are the real problem; 265P takes more liquid while staying free-running; 280P is the high-loading candidate for choline chloride, organic acids and other demanding liquids. Loading level and mixing sequence are then confirmed on a sample against your own liquid.
Usually flow. Caking in storage comes from moisture bridging and fines packing, which CENSIL 260P addresses at low dosage. If the premix was already sticky at the mixer outlet, the liquid is over-loaded on the carrier and the answer is moving up to 265P or 280P, not adding more flow aid.
Flow-aid duty in a premix usually runs 0.5–2% by weight, with 1% the usual trial start. Liquid-carrying duty is dosed to the liquid rather than to the premix, and the achievable loading is grade-dependent — we send the three grades with a suggested loading ladder so one trial finds your optimum.
Precipitated silica is entered in the EU Register of Feed Materials as silicic acid, precipitated. The grade-specific TDS, lot COA, SDS and use declaration ship with every sample so your feed-safety file has what it needs.
It can, at a cost. Plants that run both duties on one line usually keep a carrier grade and a flow grade and dose them separately — the silica cost is small against the caking losses or under-loaded carrier it prevents.
Track 02 · Food powders

Food Powder Flow

Grades: CENSIL 310 · CENSIL 320 · CENSIL 260P

Solution page →
Start with CENSIL 310, the moderate-surface porous route that suits most dry blends. Where adsorption and structure both matter — flavour carriers, powders with oil or moisture to hold — 320 is the higher-surface option. 260P covers beverage powders after spray drying, where the problem is flow and dosing rather than adsorption.
Food-grade precipitated silica is E 551 under Reg. (EU) No 231/2012 and meets 21 CFR § 172.480 in the US. Grade-specific compliance is confirmed on that grade's TDS and use declaration, which we send with the sample.
At normal dosage it is neutral in taste and white, so colour impact is negligible. Dissolution is unchanged for instant beverage powders; the one caution is over-dosing, which can leave a faint haze in clear drinks.
Blend at the same dosage into your own base, then hold sealed samples at 35–40 °C and 75% RH for 2–4 weeks alongside your current material. Judge by flow-funnel time, angle of repose and a simple caking index. We supply the comparison grade so the test is an A/B, not a single point.
Because the value shows up in the line, not on the invoice: fewer stoppages, tighter fill weights, fewer returns. A grade that costs more per kilogram at 0.6% dosage is still a rounding error against a 3% return rate.
Track 03 · Oral care

Oral Care Silica

Grades: CENSIL 310 · CENSIL 320 · CENSIL 150

Solution page →
As a screening set rather than fixed roles. 310 is the moderate-surface route usually screened for cleaning duty; 320 is the high-surface route screened for structure, viscosity and thixotropy; 150 is the fine-powder candidate for appearance and mouthfeel work. Which one carries which job is settled on your own paste.
RDA is set by the cleaning-route material and its loading. Screen 310 at a few loadings against your incumbent, measure RDA and cleaning on the lab batch — humectant, binder and fluoride system all shift the final number, so the answer lives in your formulation.
That is a structure problem, so look at the structure route first — raise the 320 level in small steps, check order of addition (silica into the glycerin/water phase before binder) and vacuum de-aeration time. Syneresis on its own points to structure or process, not to the cleaning material.
Precipitated silica carries INCI name Hydrated Silica under Reg. (EC) No 1223/2009. The grade's own TDS, SDS and heavy-metal data are part of the document set sent with the sample.
Typically Evonik ZEODENT® 113 / 165, PQ dental silica and Solvay oral-care silica. We ask to be run head-to-head as a qualified second source and let RDA, viscosity, extrusion and storage stability settle it.
Track 04 · Agrochemical

Agrochemical Carrier

Grades: CENSIL 260P · CENSIL 265P · CENSIL 280P

Solution page →
The same three-grade ladder as feed: CENSIL 260P as the base carrier, 265P where the active load is higher, 280P for the highest loadings. For WG the choice also has to pass disintegration; for SC the grades are used at low dosage as anti-settling and anti-caking aids.
No, and we say so up front. We supply the inert carrier plus adsorption, flow and anti-caking function to formulators who hold local registration. Actives, efficacy claims and registration remain entirely with the formulator.
Per dosage form: AI loading and homogeneity (WP); disintegration time and suspensibility per CIPAC MT 174 / MT 184 (WG); sedimentation, viscosity and inverted-bottle residue over accelerated storage (SC). We send the lead grade with a comparison sample so the trial reads like-for-like.
Dust follows fines and bulk density. Compare the three grades side by side on your own dosing station — the coarser-cut carrier often wins on dust even where it gives up a little adsorption.
Formulators usually start at 200 kg to 1 tonne. Grades ship in 20 or 25 kg PE-lined kraft bags on stretch-wrapped pallets, or 500 / 1,000 kg FIBC. Several grades can share one consolidated container.
Track 05 · Industrial fluoride removal

Industrial Fluoride Removal

Grades: CENSIL 320 · CENSIL 310 · CENSIL 500

Solution page →
No. Plain silica does not. Any working medium is a functionalised system — aluminium-, iron- or composite-modified — where uptake comes from the active species anchored on the silica framework. CENSIL 320, 310 and 500 are offered only as candidate substrates for such programmes, not as a finished, validated adsorbent.
After precipitation, not instead of it. Lime or calcium precipitation removes the bulk load; an adsorption stage polishes the residual few mg/L to a steady discharge figure. Scope is industrial effluent only — no drinking water, municipal supply or household units.
Raw-water review (inlet and target fluoride, pH, alkalinity, hardness, competing anions, flow) → substrate screening (320 preferred, 310 alternative, 500 as contrast) → jar tests → dynamic column trial for breakthrough and working capacity → batch supply. Engineering design and discharge compliance stay with you or your licensed local partner.
Activated alumina (DI-tech / Weco AAL-1CUFT, Tramfloc, Actas® / Bee Chems), calcium precipitation up front, strong-base anion resin and RO / NF membranes. Compare dynamic working capacity, pH window, competing-ion sensitivity, media burn rate and cost per m³ — never tonne price alone.
pH, alkalinity and phosphate. Bicarbonate and carbonate compete for sites; phosphate is the strongest competitor. These are exactly the variables the jar test is designed to expose before anyone sizes a column.
25 kg covers jar tests and comparison runs. Supply then follows the project: trial order, staged loading, replenishment by column fill volume or change-out cycle.
Track 06 · Coatings

Coating Matting & Rheology

Grades: CENSIL 230W · CENSIL 525L · CENSIL 560N

Solution page →
By system. CENSIL 230W is specially treated for waterborne compatibility and refined surfaces — first choice when a waterborne clear has to stay transparent while going matt. 525L is organically treated for resin compatibility and easy dispersion across wood, industrial, UV, plastic and leather coatings. 560N is untreated and balances matting, rheology, anti-settling and cost for industrial, coil, powder and conventional systems.
Often, but not always. Milkiness comes from refractive-index mismatch, particle size too coarse for the film thickness, or poor dispersion. Try 230W or 525L at the same gloss target, check dispersion time and film build, and read haze rather than just 60° gloss.
Same resin, same film thickness, same application method; read 60° and 85° gloss, haze on a clear, and viscosity after 24 h and after two weeks. Efficiency is gloss reduction per percent added — a grade that needs 30% more loading to reach the target is not cheaper.
Grade and treatment choice. Treated grades disperse more easily and re-suspend; untreated 560N is chosen where anti-settling additives are already in the system. We benchmark can settling and re-stir behaviour as part of the trial, not after it.
Evonik ACEMATT® OK 390 and ACEMATT® 3400, W. R. Grace SYLOID® coating matting agents and PQ / QEMETICA precipitated matting silicas. Run CENSIL head-to-head in your own clear or pigmented system and let gloss, haze, feel and rheology settle it.
Track 07 · Defoamers

Defoaming & System Stability

Grades: CENSIL 17 · CENSIL 698 · CENSIL 688

Solution page →
By the system. Mineral-oil, silicone-oil and polyether defoamers that need an anti-caking, hydrophobic component go to CENSIL 17. Powdering a liquid defoamer or oily active — taking it onto a carrier that stays easy to handle — goes to the high-absorption grades 698 and 688.
It is grade- and liquid-dependent, and it is the first thing the trial measures. We send both grades with a loading ladder; the usable loading is where the powder still flows after 24 h and after a week at 40 °C, not the highest number that mixes.
Persistence (foam regrowth over time), compatibility with the resin, emulsion, oil or water phase, cratering and surface oil on a drawdown, and storage stability across temperatures. A defoamer that kills foam and leaves craters has not solved anything.
Evonik SIPERNAT® D10, SIPERNAT® D17 and ZEOFREE® hydrophobic / carrier silicas, Wacker HDK® and Cabot CAB-O-SIL® hydrophobic fumed silica. Precipitated routes are usually compared on cost per active kilogram and on handling.
Defoamer manufacturers and compounders first, then additive makers for coatings, paper, textile, construction chemicals, wastewater and fermentation. First orders run 200 kg to 1 tonne, then follow product-line or monthly cadence.
Track 08 · Film antiblock

Plastic Film Antiblock

Grades: CENSIL 773 · CENSIL 779 · CENSIL 185P

Solution page →
CENSIL 773 is the low-iron, high-purity route where film optics matter — usually the first candidate for clear packaging film. 779 is the same platform aimed at tighter downstream appearance. 185P is the conventional precipitated comparison to run beside them when cost position has to be part of the decision.
Fix the resin, the slip-agent level and the gauge; run the candidate at two loadings against your incumbent; measure blocking force, haze, clarity, COF and gel / fish-eye count; watch screen-pack pressure and bubble stability during the run. We supply the comparison grade so the trial is an A/B.
Particle size distribution, purity and dispersion. Low-iron, tightly cut grades scatter less light at the same opening performance — which is the whole case for 773 / 779 on clear film.
Yes for the powder route: 779 serves both the film maker and the masterbatch plant whose customers judge the film by eye. Masterbatch plants that prioritise feeding and dust move to the granular grades on the masterbatch track.
W. R. Grace SYLOBLOC® 250 and the SYLOBLOC® series, Evonik SPHERILEX® and SIPERNAT® film antiblock grades, and QEMETICA / PQ precipitated antiblock silicas.
Track 09 · Masterbatch

Functional Masterbatch Dispersion

Grades: CENSIL 165GR · CENSIL 185GR · CENSIL 779

Solution page →
Granular when feeding stability and dust control drive the choice: CENSIL 165GR as the base granular grade, 185GR at a higher surface-area position for more functional loading from the same feeding behaviour. Powder 779 is the supplementary check where low iron, high purity and downstream appearance matter more than dust.
Feed-rate stability, hopper bridging and airborne dust all improve; what has to be checked is that the granule breaks down and disperses fully in the melt. Screen-pack pressure and speck count on a film strip are the two numbers that tell you.
Grade- and resin-dependent, and it is the first thing the trial measures. Loading is pushed up until screen-pack pressure, dispersion or downstream film appearance gives — the last stable point is your commercial loading.
Opening force, haze, clarity and COF on the film made from the masterbatch — because the masterbatch customer's customer judges those, not the masterbatch itself.
W. R. Grace SYLOBLOC® antiblock grades, Evonik SPHERILEX® and SIPERNAT® plastics silicas, and PQ / QEMETICA plastics antiblock and functional filler grades.
General · Ordering & supply

Ordering, samples & documentation

All grades

Quality & delivery →
Samples normally leave by air within 1–3 working days of the request: a lead grade plus a comparison grade chosen around your key metric, each with its COA. Tell us the use, the material you run today, the formulation or resin or water conditions, the equipment and the number you are chasing, and the sample set is built around that.
Formulators and compounders usually start at 200 kg to 1 tonne, often several grades side by side; coating, plastics and defoamer manufacturers at 200 kg to 1 tonne trial lots; technical distributors at 500 kg to 3 tonnes to build a sample library and base stock; fluoride projects at lab-scale samples, then by project batch.
20 kg three-ply kraft bags with PE liner (standard export pack), 25 kg bags palletised under stretch wrap, and 500 kg or 1,000 kg PE-lined FIBC (Type C or D) for bulk. Granular grades get packaging confirmed per order.
The controlled TDS for the grade, the lot COA, SDS / MSDS, use declarations and third-party test reports where required. We do not publish typical-value tables on the site; the document set is what governs supply.
Censil Silica is the functional-silica brand of Censil. We integrate material from different sources, surface treatments and forms, and pair that sourcing with application review, sampling and staged supply — the value is in matching the material to your problem, not in a single factory's fixed route.
Censil Silica is operated by Longyan Shenghe Trading Co., Ltd. in Longyan, Fujian, China, serving selected overseas customers across nine application tracks. Reach the team at sales@censilsilica.com or +1 619 558 6563.
Question not covered here?Describe your line, the material you use today and the metric you need to move — an application engineer replies directly, usually with a sample proposal.
Talk to an expert