News & Updates

Short, practical notes on fused silica specification and supply — written for buyers and engineers, updated regularly.

Investment CastingTechnicalAugust 12, 2026 · 4 min read

Why precision-casting shell rooms keep buying fresh fused silica

Short answer: because ceramic shells are single-use — and the spent material cannot be economically recovered. That makes fused silica a structural, recurring purchase for every shell room, not a one-off buy.

What happens to a shell in service

Above roughly 900 °C, fused silica in the shell transforms to β-cristobalite. The expansion that comes with that transformation is exactly why the shell is scrapped after casting — it cannot be re-used as a structural layer. Studies of shell reclamation reached a blunt conclusion: recovering spent shell material is nearly impossible, for two reasons. First, the binder's sub-micron particles have very high surface energy and devitrify. Second, sodium impurity actively promotes the phase transformation, so shells made from higher-alkali material fail sooner and more predictably.

What this means when you buy

Low alkali matters. Sodium accelerates cristobalite formation — a low-alkali, high-amorphous material gives your shell a more uniform expansion history.
Fresh material is non-negotiable. Since shells cannot be reclaimed, every shell cycle starts with new fused silica. Demand does not disappear between orders — it is continuous.
The COA is your only window into the batch. Ask for Fe₂O₃, alkali and amorphous content on every shipment, and verify them against your purchase specification.

See Grade A fused silica specs →

Reference: reclamation study of precision-casting shell material (Holt, 2021); Chemsize internal competitive-benchmark file. Figures are typical; confirm per-lot COA before quoting.

QualityBuyer GuideAugust 12, 2026 · 5 min read

How to read a fused silica COA — what actually matters

A Certificate of Analysis is only useful if you know which numbers decide whether the batch will run. Here is what we put on every Chemsize COA, and what to look at first.

1. SiO₂ — but check the method

SiO₂ looks like the headline number, yet it varies with test method and laboratory. The same material can read 99.9% by one method and up to 99.96% by another. What matters is consistency: a COA should state the method and lab, so you can compare shipments on equal terms.

2. Fe₂O₃ — the number that affects your color and electronics

For Grade A we guarantee Fe₂O₃ <50 ppm. Iron shows up as color drift in ceramics and unstable dielectric behaviour in EMC/CCL. Because our powder is ground iron-free (alumina-ceramic media and linings), the Fe₂O₃ on the COA is the Fe₂O₃ in your batch — it is not added back during processing.

3. Amorphous content — the anti-crack factor

Thermal-shock resistance comes from the amorphous structure. Grade A targets >99% amorphous (SGS). If your application is thermal-shock critical, this number matters more than SiO₂. We grade out cristobalite-rich material by hand and can supply third-party XRD verification on request.

4. Particle size — one number is not enough

We report PSD by Malvern plus standard sieves — typically D10 / D50 / D90, not a single mesh label. Two lots with the same mesh name can behave differently in slurry viscosity or packing density; D50 plus distribution width catches that.

5. What we test on every batch

Chemical composition — XRF / ICP (SiO₂, Fe₂O₃, Al₂O₃, TiO₂, alkalis)
Particle size — Malvern + standard sieves
Whiteness, pH, moisture

Every batch is sampled and tested before shipment, and the COA matches your purchase specification. Incoming inspection becomes confirmation, not discovery.

Download the TDS →

Supply updates

Shipping & capacity updates

Shipment milestones, capacity changes and product-line news are published here.

CompanyAugust 2026

Chemsize website relaunched with full technical documentation

Our product pages now carry the full grade comparison, the industry benchmark against typical international datasheets, and the TDS / brochure downloads. Shipping and capacity milestones will be posted in this section as they happen.

Spec it, and we'll back it with a COA

Tell us your mesh, grade, application and volume — we'll confirm PSD and lead time.

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