Reference
Technical guides
Straight answers to the questions that come up when you are choosing glassware: what the grades and sizes mean, what the material can take, and how to keep it working.
Glass filter porosity
What the ISO 4793 grades P0 to P5 actually mean, why a filter is rated by maximum pore size rather than a single diameter, and how the European grades line up against the American coarse/medium/fine descriptions. Includes a filtration simulator that shows what a given grade does with a given particle.
Ground glass joints
Reading a joint size, the 1:10 taper that every standard taper joint shares, and why 24/40 and 24/29 are not the same thing. Includes a fit checker that draws any two joints to scale and tells you whether they mate, partially mate, or need an adapter.
Borosilicate 3.3
Where the 3.3 comes from, the full ISO 3585 property set, the temperature limits worth memorising, and an honest list of the three things that will destroy the glass. Includes a side-by-side thermal shock comparison against ordinary soda-lime.
Care, cleaning and safe handling
The everyday routine, the specific rules for frits, joints, volumetric ware, stopcocks and Dewars, and what to look for before you pull vacuum on anything. Includes a residue-to-method picker covering the cleaning problems that actually come up.
At a glance
The numbers you look up most
Porosity grades, ISO 4793
| Grade | Max. pore | Typical use |
|---|---|---|
| P0 | 160–250 µm | Gas dispersion, filter support |
| P1 | 100–160 µm | Coarse precipitates |
| P2 | 40–100 µm | Crystalline precipitates |
| P3 | 16–40 µm | Medium analytical work |
| P4 | 10–16 µm | Fine precipitates |
| P5 | 1.0–1.6 µm | Bacterial filtration |
Borosilicate 3.3, ISO 3585
| Linear expansion | 3.3 × 10−6 K−1 |
| Density | 2.23 g/cm3 |
| Strain point | 525 °C |
| Annealing point | 565 °C |
| Softening point | 821 °C |
| Hydrolytic / acid / alkali | HGB 1 / S1 / A2 |
Full material guide, with temperature limits
Most common joint sizes
| ISO / DIN | ASTM |
|---|---|
14/23 |
14/20 |
19/26 |
19/22 |
24/29 |
24/40 |
29/32 |
29/42 |
Same row does not mean interchangeable. See why
Still not sure
Ask before you order
If you are not certain which grade, size or configuration you need, tell us what you are trying to do and we will point you at the right piece.