Thursday, October 18, 2012
06 Waste Molds Nº 38
The moulage mold, with the oil-clay leg inside of it has been wrapped up in a plastic bag for about 16 hours now. I am finally getting back to work on it. The first thing I do is to cut up a couple of cereal box cardboard boxes, into four large panels, then I trim them so they are a little bit shorter than the the mold is long. Then I find the middle of each panel and after marking it, I bend the panels on the edge of the formica molding table so they form four corners. Each of these four corners will fit over a corner of the moulage mold. The cardboard will be held in place by pieces of masking tape. I also cut a piece of cardboard long enough to go around the bottom of the mold, folded it, and taped it into place. Click on any image to enlarge it.
I took the moulage mold out of the plastic bag and carefully opened it along the seam, all the way around the edge of the mold. I am waiting for the moulage to cool down more before pouring it, so I am getting a clean parting line. I remove the oil-clay leg from the mold. I use some bathroom toilet tissue to dab out any excess moisture before closing the mold and taping the cardboard mold box around it.
This is the mold, ready to pour, with the cardboard mold box taped around it. The cardboard mold box holds the mold closed, and it allows me to handle the mold so I can pour excess carving wax back into the wax pot once it has thickened around the walls of the mold. I cover the pouring hole with a piece of plastic. Not shown in this photo, I added some masking tape around the top of the mold box before I poured the carving wax.
The carving wax being melted in a wax pot. I have two old aluminum pressure cooker pots that I use as wax pots. This one does not have any handles. The other one is a little larger, and has handles. What I did for this pour was to melt the carving wax in this wax pot, then added it to the larger wax pot, then added some more carving wax.
I have been pouring relatively small pieces so far, with these legs being the largest moulage molds that I have successfully cast into. A mold always needs more wax than it ends up with because when the casting is thick enough, the excess wax is poured back into the wax pot. This time, I am melting all the carving wax that I have, so I can pour the excess wax into a water saturated plaster mold. I am doing this so I can better estimate if I will have enough carving wax to pour the torso, or if I will need to make some more. In this photo, I have wiped the concrete studio floor with a wet rag, placed the mold on the floor, ready to be poured with carving wax, melted the carving wax, and I am waiting for the carving wax to cool a little bit before pouring it. I am using the large wax pot with handles for this pour because there is a lot of carving wax. The water saturated plaster mold has had the excess water removed from it, and it is ready to have molten carving wax poured into it.
The carving wax was poured in a steady, even stream into the moulage mold.
I fill the water saturated plaster mold with carving wax. The carving wax in the moulage mold is thickening around the walls of the mold. As it thickens, it shrinks in the pouring sprue.
When the carving wax gets thick enough, I pour the excess back into the wax pot. The moulage mold weighs about nine pounds without any carving wax in it. I tip the mold over to the side enough to get my fingers under the mold, then I lift the mold up and supporting it near the top with my other hand, I slowly pour the carving wax back into the wax pot, making sure that enough air is getting into the mold as I pour the carving wax out, so a vacuum will not be created that might collapse the casting.
The carving wax in the water saturated plaster mold solidified enough so I could score it with a knife. Scoring it now makes it easier to break into smaller pieces later on.
I pour the carving wax into the mold a total of three times, letting it thicken a little bit each time, then pouring the excess molten carving wax back into the wax pot.
I removed the first scored piece of carving wax from the water saturated plaster mold and poured a second piece.
I score the second piece of carving wax in the water saturated plaster mold. Always remember to dab out any excess water from a mold before pouring hot wax into it.
I fill the hollow carving wax casting with cool water, to help it cool down. This may be done several times because the cool water will warm up as it absorbs heat from the hot casting.
When the casting has cooled down enough, I remove the cardboard mold box and open the moulage mold. There is the cast carving wax leg in the mold.
The other side of the leg. The registration keys worked really well. This casting is much better than the casting of the other leg.
This is the moulage waste mold with the cereal box cardboard mold box. The moulage mold is ready to be cut up into chunks and stored for reuse. I put it in the plastic bag until I get a chance to cut it up. It is important to keep it moist. One of the best things about hot-melt moulage is that it is reusable.
This is where I am with my WIP BJD. The oil-clay head, arms, hands, legs, and feet have been translated into carving wax for further development. The last thing to be molded and cast is the torso.
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