Friday, October 31, 2014

09 Plaster Production Molds Nº 186




Happy Halloween !!!

The next plaster production mold will be for the other carving wax upper leg. This one has the same dimensions as the mold I just finished. The first thing I do is position the upper leg so I can draw a parting line around it. I have the leg on a board which is on a turntable, so I can rotate the leg while positioning it. A couple of pieces of oil-clay hold the leg in place, but also allow me to adjust it as needed. Click on any image to enlarge it.



Reference: 09 Plaster Production Molds Nº 149, 24 September 2014.




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Thursday, October 30, 2014

09 Plaster Production Molds Nº 185




I start the spare carving process by laying out the spare on the plaster mold with a pencil. Click on any image to enlarge it.






 I use my paring knife to carve the large end and the small end of the spare, right up to the pencil lines.






Then I carve the spare from the middle out to the pencil lines.






I use the first carving as a template to layout the second half of the spare on the other mold piece.






 I carve the small and large ends of the spare, right up to the pencil lines.






Then I carve out the rest of the spare from the middle, out to the pencil lines.






The completed spare for this mold.






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Wednesday, October 29, 2014

09 Plaster Production Molds Nº 184




This is a work-in-progress snapshot of the edges of the mold being beveled with the Surform tool. I still have to carve the spare. Click on any image to enlarge it.






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Tuesday, October 28, 2014

09 Plaster Production Molds Nº 183




I removed the coddles from the plaster mold. Click on any image to enlarge it.






I clean the oil-clay before I put the coddles away.






The mold separated cleanly.






The pattern released from the mold cleanly.






I still need to bevel the edges of the mold, and carve a spare.






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Monday, October 27, 2014

09 Plaster Production Molds Nº 182




Today I poured the third part of the mold for the upper leg. I have already cut the registration keys. I clamp the coddles around the mold as tightly as I can. I add some oil-clay coils around the inside edges to seal it. Click on any image to enlarge it.






I secure the mold to the mold table with some oil-clay coils. I will be using the mold table vibrator when I pour the plaster. If I don't secure the mold to the table, it will move around due to the vibration. I want it to stay in one place while I am pouring the plaster.






I apply the parting agent. I use a 50/50 mix of liquid soap and water. I apply the parting agent with an old paint brush. I pour the parting agent from the main supply jar to a small paint cup, and I apply the parting agent from the paint cup.






I weigh out two pounds of water in the mixing bowl. I always tare the mixing bowl to zero before I weigh the water.






I weigh out three pounds of plaster of Paris.






I quickly sift the plaster into the water. Always add plaster to water. I let it slack until it soaks up all the water. I push the island of plaster under the water and squeeze out all the lumps. The plaster is ready to pour when I can draw an "S" in the surface, and it leaves its mark. I turn on the vibrator which is attached to the mold table. I pour the plaster into the coddles evenly while the vibrator is running. This helps to release air bubbles. I turn off the vibrator. I leave the mold to setup for at least an hour.






I pour the excess plaster into the lined trash bag. I wash my hands and the mixing bowl in the bucket of water. Never put plaster (dry, set, or wet) down the drain pipes.






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Sunday, October 26, 2014

09 Plaster Production Molds Nº 181




Mold Arithmetic




6 inches x 6 inches x 1.5 inches
54.0 cubic inches

54 cuin. / 14.44 cuin. (1 cup = 14.44 cuin.)
3.73961 cups (round up to 3.75 cups)

3.75 cups * 8 ounces
30.00 ounces

30/45 (consistency ratio = 67)
.66666

30 oz. / 16 oz. (16 oz. to one pound)
1.87500 pounds water

45 oz. / 16 oz.
2.81250 pounds plaster

round up to 2 pounds water and 3 pounds plaster
2/3
.66666






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Saturday, October 25, 2014

Friday, October 24, 2014

09 Plaster Production Molds Nº 179




Today I worked on getting the mold ready for the coddles to be placed for the third part of the mold. Click on any image to enlarge it.






I must work all around the mold.






I use my Surform tool for this type of work.






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Thursday, October 23, 2014

09 Plaster Production Molds Nº 178




Today I worked around the socket end of the upper leg, removing plaster with my paring knife. Sometimes it is easier to work in the negative than the positive. Click on any image to enlarge it.






I remove any plaster that may cause an undercut for the third part of the mold.






That already looks much better.






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Wednesday, October 22, 2014

09 Plaster Production Molds Nº 177




Today I removed the coddles AND I cleaned up the oil-clay as I worked. Click on any image to enlarge it.






The other two coddles removed. It is easy to see where I placed the coils 0f oil-clay around the edges of the plaster.






The oil-clay build-up removed, revealing the socket end of the upper leg.






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Tuesday, October 21, 2014

09 Plaster Production Molds Nº 176




Today I poured the second part of the three piece plaster mold of the upper leg. Before I mixed the plaster, I added some oil-clay coils around the edges of the plaster. Click on any image to enlarge it.






As I mentioned in yesterday's post, I always soap the mold from a little paint cup. I pour some parting agent from the jar into the paint cup and work from it.






A snapshot of the mold being soaped.






I weighed the water (3.5 pounds) and the plaster (5.25 pounds), mixed them together, and poured the mold. I always let the mold setup for at least an hour before messing with it. Usually, I just wait until the next day.



One more piece to do. The third piece will not have any oil-clay build-up to mess with.




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Monday, October 20, 2014

09 Plaster Production Molds Nº 175




I continued to work on the oil-clay build-up until the coddles fit tight all around. I clamped the coddles in place. Click on any image to enlarge it.






I secured the coddles to the molding table with coils of oil-clay pressed around the bottom of the coddles.



I also mixed up a new batch of parting agent. I use a 50/50 mixture of liquid soap and water. I used the little laundry measuring cup to get equal amounts of soap and water, by volume. I use an old paint brush to apply the parting agent. I always pour some parting agent from the jar into the little paint cup when I soap the mold, so the brush won't contaminate my main supply of parting agent. So far, my molds have opened up nicely, so this parting agent works good.




This is the other side. To get these coddles nice and tight against the first part of the mold, I added a couple of "C" clamps. I will apply the parting agent before I mix the plaster.






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