Glassblowing Data, Tables, and Resources

This is a collection of handy conversion tables and other technical data that a scientific glassblower will find useful. On this page you will find:

General Glassblowing Resources Page which covers books, organizations, tool suppliers, glass suppliers, descriptions of laborator glassware, and art glass links.

Spherical Volumes

This handy chart correlates the nominal volume (V) of a sphere in milliliters to the internal diameter in millimeters:

 V (ml) ID (mm) 1 5 10 25 50 100 125 150 200 250 300 350 400 500 800 1,000 12 21 27 36 46 57 62 66 72 78 83 87 91 98 115 124

The relationship between volume and radius/diameter is given by V = (4/3)πr3 where V is the volume, r is the radius of the sphere and π = 3.1415…. This JavaScript calculator gives a precise conversion between volume in mL and inner diameter in mm:

Spherical Volume Calculator
Enter a volume or diameter:

The number above represents a:
Diameter (mm)   Volume (ml)
Enter a number, select what it represents and click Calculate. The answer will appear here.

If you need them, we also have some unit conversion calculators for distance and volume.

Cylindrical Volumes

Glassblowers sometimes need to calculate the volume of a cylinder of a given length or diamter. This handy chart lists the height and ID required to give a volume of 1 mL. For example, by looking at the chart we can see that a cylinder of ID 42 mm has volume of 1 mL for every 0.72 mm of height.

ID
mm
Height
mm
ID
mm
Height
mm
ID
mm
Height
mm
ID
mm
Height
mm
ID
mm
Height
mm
1 1274 21 2 41 0.760 61 0.340 81 0.194
2 318 22 2.630 42 0.720 62 0.330 82 0.190
3 141 23 2.450 43 0.690 63 0.320 83 0.185
4 79 24 2.210 44 0.658 64 0.310 84 0.180
5 51 25 2.030 45 0.630 65 0.300 85 0.176
6 35 26 1.880 46 0.600 66 0.292 86 0.172
7 26 27 1.740 47 0.580 67 0.283 87 0.168
8 20 28 1.620 48 0.550 68 0.275 88 0.164
9 15 29 1.510 49 0.530 69 0.267 89 0.160
10 12 30 1.410 50 0.510 70 0.260 90 0.157
11 10 31 1.320 51 0.490 71 0.252 91 0.154
12 8 32 1.240 52 0.470 72 0.245 92 0.150
13 7 33 1.170 53 0.450 73 0.239 93 0.147
14 6 34 1.100 54 0.437 74 0.232 94 0.144
15 5.660 35 1.040 55 0.420 75 0.226 95 0.141
16 5 36 0.982 56 0.406 76 0.220 96 0.138
17 4 37 0.930 57 0.392 77 0.215 97 0.135
18 3 38 0.880 58 0.378 78 0.209 98 0.133
19 3 39 0.837 59 0.366 79 0.204 99 0.130
20 3 40 0.790 60 0.356 80 0.199 100 0.127

The relationship between the height, radius/diameter and volume of a cylinder is given by V=hπr2 where V is the volume, h is the height, r is the radius (half the inner diameter) and π = 3.1415…. In the JavaScipt calculator below, you can enter any two of the three variables and it will determine the value of the third one for you.

Cylindrical Volume Calculator
Enter any two of the three variables and then hit the Calculate button next to the value you wish to determine.
Height (mm)
Inner Diameter (mm)
Volume (mL)

If you need them, we also have some unit conversion calculators for distance and volume.

Fractional Inches to Millimeter Conversions

Glassblowers routinely use calipers to measure glassware, and some of these even read in both inches and millimeters. However, most calipers do not handle fractional measurements such as 11/16". This table is list of fractional measurements along with their decimal and millimeter equivalents that you may want to print and hang by your workbench. This table is great for woodworkers,too!

Fraction (Inches) Decimal (Inches) Millimeters
1/64 0.015625 0.396875
1/32 .03125 0.7938
1/16 0.0625 1.5875
1/8 0.125 3.1750
3/16 0.1875 4.7625
1/4 0.250 6.3500
5/16 0.3125 7.9375
3/8 0.375 9.5250
7/16 0.4375 11.1125
1/2 0.500 12.7001
9/16 0.5625 14.2876
5/8 0.625 15.8751
11/16 0.6875 17.4625
3/4 0.750 19.0501
13/16 0.8125 20.6375
7/8 0.875 22.2251
15/16 0.9375 23.8125
1 1.00 25.4001

Temperature Conversions

Most digital thermometers and optical pyrometers read in both Farenheit and Celsius, so we won't preent a table here. You can convert temperature units with our handy JavaScript temperature conversion calculator. And here are the conversion formula if you are really Old School and want to use your TI-30 or slide rule:

 Centigrade to Fahrenheit Fahrenheit to Centigrade (C x 9/5) + 32 = F (F - 32) x 5/9 = C

Pressure Conversions

You can convert presure units with our handy JavaScript pressure conversion calculator. Here's a conversion table in case you are allergic to JavaScript:

mbarTorrinches HgpsiPa
mbar 1 0.750 0.0295 0.0145 100
Torr 1.333 1 0.0394 0.0193 133.32
Inches Hg33.864 25.409 1 0.491 3,386.33
psi68.946 51.714 2.036 1 6,894.65
Pa0.01 0.00750 0.000295 0.000145 1

Glass Tubing Pressure Nomogram

Glass can be used under vacuum or pressure, but the larger the pressure differential, the thicker the glass must be. Even so, every time the glassware is used under pressure differentials of more than one atmosphere (760 torr) it must be thoroughly inspected for defects, star cracks and other potential points of failure before pressurization. Safety shields and other forms of protection are also necessary.

This handy nomograph tells the glassblower how thick the wall of a borosilicate glass tube should be in order to withstand a given pressure. One should always build in an extra margin of safety when designing such apparatus:

See this diagram full size

Physical Properties of Common Glasses

 Soft Glass(Soda Lime) Borosilicate(Duran, Kimax, Pyrex) Quartz(Fused Silica) All temperatures are given in degrees C Softening Range 696 821 1580 Working Range 1000 1200 1800 Annealing Range 514 565 1050 Max Service Temp. 450 490 1100

The information in this section should be used as a source of comparative figures only, representing a broad range of glasses within their respective family groups. For specific technical data each glass should be identified as to manufacturer and glass code number.

Glass to Metal Sealing Combinations

 On occasion, a glassblower may be asked to construct a piece made of glass and some other material. For example, a conductivit cell might need an electrode embedded in the glass or a glass high vacuum manifold may need to mate to a metal thermocouple. Making such connections directly is nearly impossible because the two materials have to have very similar thermal coefficients of expansion and other properties. By using a graded seal like the one shown to the right, one can join extremely short lengths of glass that vary from each other by just a little bit and achieve a smooth transition from one material to another. These will span the range between the borosilicate or quartz and the other material. These table below contains some of the most common combinations.
Material Material to Glass Seal
Platinum 7740 (not vacuum tight)
Tungsten 3320 - 7740
Kovar 7052 - 7720 - 3320 - 7740
Alumina 7280 - 7056 - 7052 - 3320 - 7740
Tungsten to Quartz Seal
Tungsten 0.30 - 0.40 mil 7230 sleeve or GE#1 cane - Fused Quartz
Numbers refer to Corning code numbers

Vacuum Formed 0.500" OD Quartz Tubing

Start with a 0.374" graphite machined rod mandrel and 10 mm ID x 13 mm OD Quartz starting stock

Glass Frit Porosities

 Fritted glass is a porus filter made of glass fibers or granules. They are widely used in inorganic and organic laboratories and come in many different forms. Fritted funnels are used for liquid/solid separation and purification. Fritted gas dispersion tubes are used to absorb/remove/dry gases, disperse gases in liquid solutions, and many other applications. They are typically found in disc or cylindrical form in borosilicate and quartz glass. You can learn more about glass fritted funnels and their care in the Glassware Gallery.

This chart shows the porosity designations and their meanings for glass frit proucts from Ace, Corning, and Kimble:

Porosity Range Cross Reference Chart (microns)
Common Uses Ace Corning Kimble
Gas Dispersion, Coarse Filtration A
145-174
EC
170 - 220
EC
170 - 220
Filtration, Gas Dispersion C
25-50
C
40-60
C
40-60
Filtration, Extraction D
10-20
M
10-15
M
10-15
Filtration, Extraction E
4-8
F
4-5.5
F
4-5.5
Bacteria Filtration VF
2-2.5
VF
2-2.5
xx

EC = Extra Coarse, C = Coarse, M = Medium, F = Fine, VF= Very Fine

General and Miscellaneous Technical Resources

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