GUOLIANInorganic Silicates · Est. 1980
Acidic · large-particle · alumina

Specialty sols

These grades are for the applications standard alkaline colloidal silica cannot cover: acidic or cationic systems, polishing that needs a higher removal rate, and coatings that need a positively charged inorganic particle.

Sample bottles of milky alumina sol, clear acidic silica sol and bluish-white large-particle sol
Illustration (AI-generated): alumina sol (milky), acidic colloidal silica (clear), large-particle silica sol (bluish-white).

Acidic colloidal silica (CH83-A30)

This colloidal silica is stabilised at acidic pH instead of with alkali. It can be used where an alkaline sol would gel or would upset the system:

  • acidic coatings and binders;
  • paper anti-slip and surface treatments on lines that run acidic or use cationic additives;
  • formulations that must stay low in alkali.
Grade
CH83-A30
SiO₂
30 ± 2 %
Na₂O
≤ 0.05 %
pH
2.0–4.0
Density, 20 °C
1.190–1.210 g/cm³
Avg. particle size
8–15 nm
Particle charge
Negative

Large-particle colloidal silica (CH83-A1030)

Our standard CH83-1 grades run from 3 to 15 nm. The large-particle grade is for applications that benefit from bigger particles:

  • Polishing. Larger particles give a higher material removal rate on glass, sapphire, stone and metals.
  • Binders and coatings. Larger particles give lower viscosity at the same solids content and a different packing structure in the dried film.
Grade
CH83-A1030
Avg. particle size
80–100 nm
SiO₂
30 ± 2 %
Na₂O
≤ 0.05 %
pH
2.0–4.0 (acidic)
Density, 20 °C
1.190–1.210 g/cm³

This grade is supplied for general polishing. Semiconductor CMP slurries need ultra-high-purity silica made by a different process, which this product is not.

Alumina sol (GHAL)

Alumina sol is a colloidal dispersion of hydrated aluminium oxide. Unlike silica, its particles carry a positive charge, which makes it compatible with cationic systems. Uses:

  • Premium electrostatic flocking: electro-finishing of high-grade flock fibre (flocking);
  • Inkjet receptive coatings: a porous, dye-fixing layer, used with our cationic emulsion GH2019 (inkjet coatings);
  • Refractory and ceramic fibre: a high-temperature binder;
  • Catalyst and catalyst carrier for the petrochemical industry;
  • Precision casting, glass enamel and ceramics: binder and additive;
  • Fabric and fibre processing: a film former; also an emulsifier and stabiliser for pigments and paints.
GradeCompositionSolids
GHAL10a(Al₂O₃·nH₂O)·bHX·cH₂O10 ± 1 %
GHAL20a(Al₂O₃·nH₂O)·bHX·cH₂O20 ± 1 %
Appearance
Translucent to milky, viscous colloid; thixotropic
Behaviour
Thins on contact with acid or alkali; converts to active alumina when dehydrated at high temperature
pH
2.0–4.0
Particle size
on request
Packaging
25 kg, 50 kg or 125 kg drums, or to order
Storage
5–35 °C indoors; shelf life 6 months
Classification
Non-hazardous for transport; SDS available

Frequently asked questions

What is the difference between alkaline and acidic colloidal silica?
Alkaline colloidal silica is stabilised with sodium or ammonia at around pH 8.5–11 and carries a negative charge. Acidic colloidal silica is stabilised at low pH, so it can be used in acidic systems. Its particles are still negatively charged, so it is not a substitute for a cationic sol.
When should I use alumina sol instead of colloidal silica?
Use alumina sol when you need a positively charged inorganic particle. Typical cases are cationic inkjet coatings, some premium flock treatments, and alumina-based refractory or ceramic fibre binders.
Can your large-particle silica sol be used for chip (CMP) polishing?
No. It is intended for general polishing of glass, sapphire, stone and metals. Semiconductor CMP needs ultra-high-purity slurries made by a different process.

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