| How to... Mix plaster and gysum cement. |
Mixing Instructions
Storage: Store plaster/gypsum in a warm, dry area,
raised from the floor to avoid moisture absorption. The shelf life
of all plaster/gypsum is limited but that life can be extended by
storing in air-tight plastic containers.
- Weigh proper amount of room temperature water in a clean container.
(Warmer water will accelerate the setting time.)
- Weigh proper amount of plaster/gypsum.
- Sprinkle the plaster/gypsum into the water. (Never pour water
into plaster/gypsum). As you near completion, small mounds of
plaster will peak above the surface of the water. When all the
plaster/gypsum has been added, allow the mixture to sit undisturbed
while the plaster soaks up the water. (Several minutes).
- Manually: It is possible to get a good mix
by using a spoon or wood dowel. Mix slowly and steadily from the
bottom, using a side to side motion. Stirring in a circular motion
will introduce undesirable air bubbles into the mix. Consistency
of final mix should be that of heavy dairy cream. (The "old
timers" are sometimes seen "elbow deep in plaster"
literally mixing by hand. This is a very dangerous method since
plaster becomes extremely hot when setting, potentially resulting
in severe burns.)
Electric Mixer: You can achieve a consistently
good mix by using an electric drill with a Jiffy Mixer attachment.
"Stir" at 1750 RPM while holding the Jiffy Mixer at
151/2 off vertical. This method is also quicker than the manual
method discussed above.
|
Consistency and Setting
Times |
USG
Product |
|
Recommended
Consistency* |
|
Approximate
Setting Time |
|
| Ceramical |
|
40 |
|
18 - 23 minutes |
| Duracal/Fastcast |
|
26 |
|
25 - 35 minutes |
| Duramold |
|
68 |
|
27 - 37 minutes |
| Hydrocal A-11 |
|
42 |
|
16 - 20 minutes |
| Hydrocal B-11 |
|
44 |
|
25 - 35 minutes |
| Hydrocal FGR 95 |
|
30 |
|
50 - 70 minutes |
| Hydrocal White |
|
45 |
|
25 - 35 minutes |
| Hydroperm |
|
100 |
|
12 - 19 minutes |
| Hydro-stone |
|
32 |
|
17 - 20 minutes |
| Hydro-stone Super X |
|
22 |
|
17 - 20 minutes |
| Hydro-stone TB |
|
32 |
|
17 - 20 minutes |
| No. 1 Pottery |
|
70 |
|
27 - 37 minutes |
| Puritan Pottery |
|
66 |
|
27 - 37 minutes |
| Regular Casting |
|
72 |
|
27 - 37 minutes |
| Regular Pottery |
|
74 |
|
27 - 37 minutes |
| Statuary Hydrocal |
|
40 |
|
25 - 35 minutes |
| Tuf-Cal - 20 Minute |
|
50 |
|
17 - 22 minutes |
| Tuf-Cal - 30 Minute |
|
50 |
|
27 - 35 minutes |
| Ultracal 30 |
|
38 |
|
25 - 35 minutes |
| White Art - 20 Minute |
|
70 |
|
17 - 27 minutes |
| White Art - 30 Minute |
|
70 |
|
27 - 37 minutes |
|
| * Parts of water by weight per 100 parts of material |
|
Bulletin Board &