For coating‑glass blasting booth, white fused alumina grit is used for coating layer removal, glass substrate matte roughening, pre‑coating substrate pretreatment and defective‑coating rework & stripping. Core requirements: zero iron contamination, no residual discoloration, recyclable performance and controllable dust. Iron impurities must be avoided, as they will cause pin‑points and rainbow defects in subsequent coating processes.
Coarse‑grained high‑purity white fused alumina applies to heavy‑duty stripping of thick coatings, heavy paint layers and thick oxide films on thick glass. Grades 80#, 100#, 120# and 150# are suitable for regular LOW‑E and ITO coating rework.
| FEPA Grit | Applicable Process | Recommended Blasting Pressure | Remarks & Risk Notes |
|---|---|---|---|
| F24 | Heavy stripping of aged thick coatings on thick tempered scrap glass | 0.25‑0.32 MPa | Coarse particles easily cause deep scratches and chipping. Forbidden for qualified LOW‑E / ITO workpieces. |
| F80 | Rework and stripping of stubborn LOW‑E & ITO coatings; the most widely‑used main‑stream grit in factories | 0.35‑0.42 MPa | Balances coating‑removal efficiency and glass surface quality, ideal for mass‑production rework lines. |
| F100 | LOW‑E / ITO coating stripping; balanced removal efficiency and fine matte finish; preferred for thin‑glass rework | 0.33‑0.40 MPa | Lower scratch risk than F80; widely adopted in most domestic coating blasting booths. |
| F120 | Substrate pre‑roughening before coating to improve subsequent coating adhesion; rework of slightly defective coatings | 0.32‑0.38 MPa | Uniform and delicate matte surface without deep grooves; first choice for pretreatment of qualified products. |
| F150 | Pretreatment for thin‑glass substrates and high‑end coating substrates; light‑duty matte roughening with barely any substrate damage | 0.30‑0.36 MPa | Weak cutting capacity; cannot strip intact old coatings, not fit for large‑scale coating‑removal operations. |
Key Points for White Fused Alumina Selection
- For rework of defective workpieces (LOW‑E / ITO coatings): prioritize F80 and F100.
- For substrate roughening before coating to enhance coating adhesion: prioritize F120 and F150.
- Avoid F24 for all thin glass. The coarser the grit, the lower the blasting pressure shall be set.
Important Notes for Coating‑Line Blasting Booths
- Magnetically‑separated iron‑free white fused alumina is mandatory. Ordinary white fused alumina contains iron impurities that trigger pin‑holes and rainbow pattern defects on coated glass.
- The blasting‑booth reclaiming system shall be equipped with air‑wash classifier and magnetic separator to discharge fractured fine powder in a timely manner. Excessive fine powder results in hazy glass surfaces and reduced coating yield.
- Compressed air must be free of water and oil. Moisture content of abrasive shall be kept below 1%.