1/ Bubbles and inclusions

Q: What does 1/ 3x0.16 mean?

At most 3 bubbles or inclusions of grade 0.16 (projected area up to 0.0256 mm² each); the summed area of the counted bubbles may not exceed 3 × 0.16² = 0.0768 mm².

Q: Why are bubble grades numbers like 0.16 and 0.63?

They come from the Renard R5 preferred-number series; each grade is the square root of an area in mm.

Code 1/ limits bubbles and inclusions in the glass. Like the other material codes it goes in the material field of the drawing table.

Standard: ISO 10110-18:2018

Decode a callout →Use it in a drawing →Build a 1/ callout

Syntax

1/N×A	A = grade number of the largest permitted bubble (the square root of its projected area, in mm); N = max. number of bubbles of that grade.
01/N×A · 11/N×A	Raw material · finished assembly.

Worked examples

1/ 3x0.16	Up to 3 bubbles of grade 0.16 (each ≤ 0.0256 mm² projected area). Total area of all counted bubbles ≤ 3 × 0.16² = 0.0768 mm².
1/ 1x0.25	One bubble of grade 0.25; total area ≤ 0.0625 mm².
1/ 5x0.063	5 bubbles of grade 0.063; total ≤ 0.0198 mm².

Click an example to open it in the decoder.

Common values and typical grades

Grades (Table 1)	0.006, 0.010, 0.016, 0.025, 0.040, 0.063, 0.10, 0.16, 0.25, 0.40, 0.63, 1.0, 1.6, 2.5, 4.0 (Renard R5 steps, ≈ ×1.6)
Counts	1, 2, 3, 5, 10, 20 are the usual choices

Accumulation: the summed projected area of all bubbles with grade ≤ A and > 0.16·A must not exceed N·A² mm². Concentrations (more than 20 % of the allowed max-grade bubbles in any 5 % sub-area; two or more if N < 10) are not allowed.

Common mistakes

Reading A as a diameter. A is the square root of an area: grade 0.16 means 0.0256 mm², not a 0.16 mm bubble.
Inventing grades between the standard steps (e.g. 0.2). Use the R5 series.
Forgetting the accumulation rule: N×A also caps the total area of smaller bubbles.

Questions

What does 1/ 3x0.16 mean?

At most 3 bubbles or inclusions of grade 0.16 (projected area up to 0.0256 mm² each); the summed area of the counted bubbles may not exceed 3 × 0.16² = 0.0768 mm².

Why are bubble grades numbers like 0.16 and 0.63?

They come from the Renard R5 preferred-number series; each grade is the square root of an area in mm.

Sources

ISO 10110-18:2018 (bubbles and inclusions; replaces ISO 10110-3). Full list and edition status: Sources & editions.

An unofficial summary written from public previews of the standards and reputable secondary sources. It does not reproduce the ISO text. Items marked verify could not be fully confirmed. Check against the current edition; see Sources & editions.