Aluminum sulfate (alum, CAS 10043-01-3) is best known for water treatment, but it is also a workhorse in papermaking, dyeing, construction and many other industries. This guide covers alum’s industrial uses beyond water treatment and what buyers should consider for each application.
1. Papermaking
Alum is a traditional papermaking chemical, used for:
- Rosin sizing: alum precipitates rosin size onto fibers, making paper water-resistant.
- pH control: adjusts the wet-end pH for sizing and retention.
- Retention and drainage aid: in traditional (acidic) papermaking systems.
Note: modern papermaking has shifted toward neutral/alkaline systems, reducing alum use, but it remains relevant for specialty grades.
2. Dyeing and Textiles
- Mordant: alum fixes dyes onto fibers (especially natural dyes).
- Precipitation auxiliary: used in dye bath processing.
3. Construction and Other Uses
- Concrete accelerator/setting modifier: alum accelerates concrete setting in some applications.
- Tanning auxiliary: aluminum salts in leather tanning.
- Fire-retardant additive: in some material treatments.
- Gardening/soil amendment: acidifies alkaline soils.
4. Grades and Forms
| Form | Typical use |
|---|---|
| Lump/ground (17% Al2O3) | Water treatment, general industrial |
| Iron-free grade | Papermaking, dyeing (low iron matters for color) |
| Technical vs food/pharma grade | Confirm per application |
5. FAQ
Is alum still used in papermaking?
Yes, especially in rosin-sized and specialty papers, though neutral sizing has reduced overall demand.
What is the difference between alum grades?
Mainly aluminum oxide content and iron level; iron-free grades are required where color matters (paper, dyeing).
Can alum be used in soil?
Yes — it acidifies alkaline soil and is used in gardening; verify application rates.
Is alum the same as PAC?
No — PAC is polyaluminum chloride, a pre-hydrolyzed polymerized form with different coagulation behavior.
6. References and Further Reading
- Papermaking and textile industry literature on alum use
- Industrial chemical specifications for aluminum sulfate grades
This article is published for industrial and technical reference by PolyblueChem. Verify grade suitability for your application.
PolyblueChem supplies aluminum sulfate (CAS 10043-01-3) in multiple grades with COA and MSDS. Contact us for specifications and quotations.