Number 1 Pottery Plaster
% of water to dry mix by weight - 70%
Set Time – 27 – 37 mins
Dry density – 1105 kg/cubic metre
Expansion on setting – 0.21%
Compressive strength - 126 kg./square centimeter
No. 1 Casting plaster% of water to dry mix by weight - 70%
Set Time – 27 – 37 mins
Dry density – 1058 kg/cubic metre
Expansion on setting – 0.2%
Compressive strength - 140 kg./square centimeter
Plaster of Paris% of water to dry mix by weight - 70%
Set Time – 27 – 37 mins
Dry density – 1105 kg/cubic metre
Expansion on setting – 0.2%
Compressive strength - 140 kg./square centimeter
Number 1 Casting Plaster% of water to dry mix by weight - 65%
Set Time – 27 – 37 mins
Dry density – 1162 kg/cubic metre
Expansion on setting – 0.22%
Compressive strength - 168 kg./square centimeter
Pottery Plaster
% of water to dry mix by weight - 74%
Set Time – 27 – 37 mins
Dry density – 1162 kg/cubic metre
Expansion on setting – 0.19%
Compressive strength - 126 kg./square centimeter
Hydrocal Cement
% of water to dry mix by weight - 45%
Set Time – 25 – 35 mins
Dry density – 1442 kg/cubic metre
Expansion on setting – 0.39%
Compressive strength – 35 kg./square centimeter
Hydroperm Cement% of water to dry mix by weight - 10%
Set Time – 12 -19 mins
Dry density –
<641 br="" cubic="" kg="" metre="">Expansion on setting – 0.14%
Compressive strength – 35 kg./square centimeter
Hydro-Stone cement
% of water to dry mix by weight - 32%
Set Time – 17 -20 mins
Dry density – 1913 kg/cubic metre
Expansion on setting – 0.24%
Compressive strength – 703 kg./square centimeter
Ultracal cement
% of water to dry mix by weight - 38%
Set Time – 25 - 35 mins
Dry density – 1568 kg/cubic metre
Expansion on setting – 0.08%
Compressive strength – 421 kg./square centimeter
Saturday, 27 February 2010
Tuesday, 23 February 2010
Break Down Temperatures of Common Mould Constituents
Binders are essential parts of mould materials. They hold the refractory parts of the mould together. Selection is dependent on the temperature you will be using. This also is important in choosing the refractory material to use.
Gypsum plaster - 704C – 816C
Hydrocal cement - 704C – 816C
Hydroperm cement – 760C – 927C
Colloidal silica – 1260C
Colloidal alumina – 1260C
Calcium alumina cement (cement fondu) – 1538C
There are of course, many other factors to take into account when choosing binders and refractory materials for moulds.
Gypsum plaster - 704C – 816C
Hydrocal cement - 704C – 816C
Hydroperm cement – 760C – 927C
Colloidal silica – 1260C
Colloidal alumina – 1260C
Calcium alumina cement (cement fondu) – 1538C
There are of course, many other factors to take into account when choosing binders and refractory materials for moulds.
Friday, 19 February 2010
Temperature Characteristics of Various Glasses
Over the years I have collected temperature information for a number of glasses. They are of comparative interest and can assist with choosing a temperature or range of temperatures for the work you are doing. If the work is important, or critical, refer to the manufacturer for the latest information.
Bullseye
There has been a lot of information published about this glass. One interesting characteristic has been the different temperatures for the complete range of glass they produce. So there appears to be a difference between the transparent, opalescent and gold pink glasses.
Transparent:
Full Fusing 832C ; Tack Fusing 777C ; Softening 677C ; Annealing 532C ; Strain 493C
Opalescent:
Full Fusing 843C ; Tack Fusing 788C ; Softening 688C ; Annealing 502C ; Strain 463C
Gold Bearing:
Full Fusing 788C ; Tack Fusing 732C ; Softening 635C ; Annealing 472C ; Strain 438C
This also illustrates that not all the characteristics of a glass range are linear. The most apparent one is that the full fusing, tack fusing and softening points of the opalescent glass are higher than transparent, although the annealing point is lower.
Desag GNA
Full Fusing 857C ; Tack Fusing 802C ; Softening 718C ; Annealing 516C ; Strain 427C
Float Glass
Full Fusing 835C ; Tack Fusing ca. 760C ; Softening 720C ; Annealing ca. 530C ; Strain 454
Spectrum S96
Full Fusing 788C ; Tack Fusing 718C ; Softening 677C ; Annealing 510C ; Strain 371C
Uroboros
Full Fusing 788C ; Tack Fusing 732C ; Softening 663C ; Annealing 538C ; Strain 427C
Although the information above may be dated, the important element is that there is little correlation between glasses in the relationship of annealing point to other characteristics of the glass.
This listing also shows that the temperature characteristics are not linear between glasses. For example, Spectrum and Uroboros have the same full fuse temperatures, but different tack fusing, softening, annealing and strain temperatures. Sometimes one is higher than the other, and other times it is reversed.
Another example is shown by the Desag GNA and Float glasses. Desag GNA has higher full fuse and tack fuse temperatures than float, but lower softening, annealing and strain temperatures. This helps to make the point that you need to know the glass you are using as it will not have a proportional relationship at every point in the kiln working temperature range.
I emphasise that these temperatures have been collected over a period and may not be the current or absolutely correct information. They are used here to illustrate the differences within and between the glasses of various manufacturers.
Bullseye
There has been a lot of information published about this glass. One interesting characteristic has been the different temperatures for the complete range of glass they produce. So there appears to be a difference between the transparent, opalescent and gold pink glasses.
Transparent:
Full Fusing 832C ; Tack Fusing 777C ; Softening 677C ; Annealing 532C ; Strain 493C
Opalescent:
Full Fusing 843C ; Tack Fusing 788C ; Softening 688C ; Annealing 502C ; Strain 463C
Gold Bearing:
Full Fusing 788C ; Tack Fusing 732C ; Softening 635C ; Annealing 472C ; Strain 438C
This also illustrates that not all the characteristics of a glass range are linear. The most apparent one is that the full fusing, tack fusing and softening points of the opalescent glass are higher than transparent, although the annealing point is lower.
Desag GNA
Full Fusing 857C ; Tack Fusing 802C ; Softening 718C ; Annealing 516C ; Strain 427C
Float Glass
Full Fusing 835C ; Tack Fusing ca. 760C ; Softening 720C ; Annealing ca. 530C ; Strain 454
Spectrum S96
Full Fusing 788C ; Tack Fusing 718C ; Softening 677C ; Annealing 510C ; Strain 371C
Uroboros
Full Fusing 788C ; Tack Fusing 732C ; Softening 663C ; Annealing 538C ; Strain 427C
Although the information above may be dated, the important element is that there is little correlation between glasses in the relationship of annealing point to other characteristics of the glass.
This listing also shows that the temperature characteristics are not linear between glasses. For example, Spectrum and Uroboros have the same full fuse temperatures, but different tack fusing, softening, annealing and strain temperatures. Sometimes one is higher than the other, and other times it is reversed.
Another example is shown by the Desag GNA and Float glasses. Desag GNA has higher full fuse and tack fuse temperatures than float, but lower softening, annealing and strain temperatures. This helps to make the point that you need to know the glass you are using as it will not have a proportional relationship at every point in the kiln working temperature range.
I emphasise that these temperatures have been collected over a period and may not be the current or absolutely correct information. They are used here to illustrate the differences within and between the glasses of various manufacturers.
Monday, 15 February 2010
Mesh Sizes
Mesh and grit sizes are most often refered to by a number. This relates to the number of wires per inch - and in a subsidary fashion also to the size of the wire used to form the grid through which the material falls and so is sorted into various sizes. The table below gives some of these figures most useful for mould making - mesh number, percentage of open area, the wire diameters in mm, and the mesh opening or material size in mm.
No.12 ; % open 51.8 ; dia. 0.5842 ; size 1.5240
No.14 ; % open 51.0 ;dia. 0.5080 ; size 1.2954
No.20 ; % open 46.2 ; dia. 0.4064 ; size 0.8636
No.30 ; % open 37.1 ; dia. 0.3048 ; size 0.5156
No.40 ; % open 36.0 ; dia. 0.2286 ; size 0.3810
No.50 ; % open 30.3 ; dia. 0.1905 ; size 0.2794
No.60 ; % open 30.5 ; dia. 0.1397 ; size 0.2337
No.80 ; % open 31.4 ; dia. 0.1143 ; size 0.1778
No.100;% open 30.3 ; dia. 0.0940 ; size 0.1397
No.120; % open 30.7 ; dia. 0.0940 ; size 0.1168
No.200; % open 33.6 ; dia. 0.0533 ; size 0.0737
No.325;% open 30.0 ; dia. 0.0356 ; size 0.0432
No.12 ; % open 51.8 ; dia. 0.5842 ; size 1.5240
No.14 ; % open 51.0 ;dia. 0.5080 ; size 1.2954
No.20 ; % open 46.2 ; dia. 0.4064 ; size 0.8636
No.30 ; % open 37.1 ; dia. 0.3048 ; size 0.5156
No.40 ; % open 36.0 ; dia. 0.2286 ; size 0.3810
No.50 ; % open 30.3 ; dia. 0.1905 ; size 0.2794
No.60 ; % open 30.5 ; dia. 0.1397 ; size 0.2337
No.80 ; % open 31.4 ; dia. 0.1143 ; size 0.1778
No.100;% open 30.3 ; dia. 0.0940 ; size 0.1397
No.120; % open 30.7 ; dia. 0.0940 ; size 0.1168
No.200; % open 33.6 ; dia. 0.0533 ; size 0.0737
No.325;% open 30.0 ; dia. 0.0356 ; size 0.0432
Thursday, 11 February 2010
Properties of Some Basic Glass Types
Various types of glass have differing properties which make them suitable for a variety of applications. Some of the characteristics of three glasses are given here. The glasses are quartz, soda/lime, and lead crystal.
Quartz glass
Softening point (C) 1508
Annealing point (C) 1048
Strain point (C) 956
CoE at 10-7 metres/degree C: 3.1
Density (kg/m3) 1973
Refractive index 1.459
Soda/Lime glass
Softening point (C) 693 - 732
Annealing point (C) 516 - 549
Strain point (C) 471 - 493
CoE at 10-7 metres/degree C: 56 - 100
Density (kg/m3) 2203 - 2275
Refractive index 1.51 – 1.52
Lead glass
Softening point (C) 438 - 671
Annealing point (C) 366 - 527
Strain point (C) 343 - 449
CoE at 10-7 metres/degree C: 47 - 55
Density (kg/m3) 2505 - 4867
Refractive index 1.54 – 1.75
Quartz glass
Softening point (C) 1508
Annealing point (C) 1048
Strain point (C) 956
CoE at 10-7 metres/degree C: 3.1
Density (kg/m3) 1973
Refractive index 1.459
Soda/Lime glass
Softening point (C) 693 - 732
Annealing point (C) 516 - 549
Strain point (C) 471 - 493
CoE at 10-7 metres/degree C: 56 - 100
Density (kg/m3) 2203 - 2275
Refractive index 1.51 – 1.52
Lead glass
Softening point (C) 438 - 671
Annealing point (C) 366 - 527
Strain point (C) 343 - 449
CoE at 10-7 metres/degree C: 47 - 55
Density (kg/m3) 2505 - 4867
Refractive index 1.54 – 1.75
Subscribe to:
Posts (Atom)