Public Resources Code section 19515.5

Chemical Composition
Tolerance
(+ or -
Oxides
Percentage Weight
Percentage Range)
Silicon Dioxide
66-75
1.00
Aluminum Oxide
0-7
0.50
Calcium Oxide
5-15
0.50
Magnesium Oxide
0-5
0.50
Sodium Oxide
8-18
0.50
Potassium Oxide
0-4
0.50
Iron Oxide
less than 0.5
0.05
Chromium Oxide
less than 0.1
0.02
Sulfur Trioxide
less than 0.2
0.02
All other oxides
less than 0.1
0.02
Organic Carbon
less than 0.1
0.02
Moisture Content
less than 0.5
0.05
(No caking with free-flowing fiberglass)
Loss on Ignition
less than 1.0
0.10

Source: Section 19515.5, https://leginfo.­legislature.­ca.­gov/faces/codes_displaySection.­xhtml?lawCode=PRC§ionNum=19515.­5.­ (updated Jan. 1, 1991; accessed Dec. 29, 2025).

Green check means up to date. Up to date

Verified:
Dec. 29, 2025

§ 19515.5's source at ca​.gov