This blog will be a two part discussion of the mother mold created for the clay foot and latex mold and of the subsequent casting of the first test foot (TF1) using the aforementioned latex mold.
The latex ended up staying on the clay foot model for approximately 36 hours. Normally I wouldn't leave it in place that long but I had better things to do. After running out of better things to do I set about prepping the clay foot and latex mold to create a mother mold. The mother mold is a second mold created over the existing mold, and serves as a support to the latex during the casting process.
(Clay foot and latex mold before the mother shows up.)Before I go any further I will say this isn't the end all be all of copying models or casts. It's just a method that I've found works well for me (so all you modeling and casting nerds can stick it before you get riled up).
The first part of the process in making the mother mold is locating a trash bag. I like to use the heavy duty lawn bags. Take the bottom of the bag and smooth it out over the surface of the latex mold. Where spaces like in between toes are concerned you want to make sure the bag goes between them but not to the point of being form fitting. That extra little bit of space will be necessary for extracting the model from the mother mold. Too close a fit and the mother mold and model will lock together.
(Thus the bag is applied to the model.)
The first part of the process in making the mother mold is locating a trash bag. I like to use the heavy duty lawn bags. Take the bottom of the bag and smooth it out over the surface of the latex mold. Where spaces like in between toes are concerned you want to make sure the bag goes between them but not to the point of being form fitting. That extra little bit of space will be necessary for extracting the model from the mother mold. Too close a fit and the mother mold and model will lock together.
(Thus the bag is applied to the model.)Once the bag is applied over the surface of the model you need a box. The box should be roughly the same size as the model while leaving a little room around the edges. It also needs to be deeper than the model. Cut open the bottom of the box and pull the trash bag up through it, while leaving the bag firmly impressed over the model.
(Thus the box is applied to the bag which is applied to the model.)
(Thus the box is applied to the bag which is applied to the model.)That's it for prep. At this point the only thing left is to mix up enough plaster of paris (PoP) to completely fill the box up to the point that the model is completely submerged.
(Thus the PoP is applied to the box that was applied to the bag that was applied to the model.)
(Thus the PoP is applied to the box that was applied to the bag that was applied to the model.)The only thing left to do now is sit back and wait. Time allowed varies depending on how much PoP was neccesary. I managed to keep myself occupied for about three hours. In any case it's important to allow enough time for the plaster to fully set.
(This killing time is killing me.)
Once the plaster is set you simply lift up the whole package (box, mother mold, bag, latex mold and model) and gently turn them over and remove in the opposite order. Depending on how good a job you did smoothing out the bag it will or won't have bound in folds of the plaster. Just gently tear it away.
(Cracks kill.)
(This killing time is killing me.)Once the plaster is set you simply lift up the whole package (box, mother mold, bag, latex mold and model) and gently turn them over and remove in the opposite order. Depending on how good a job you did smoothing out the bag it will or won't have bound in folds of the plaster. Just gently tear it away.
(Cracks kill.)Unfortunately as the above photo illustrates my clay foot had some serious structure related deficiencies on the underside. Since it was only ever intended to be a model for the creation of TF1 I only shed a few tears as it crumbled out of the latex mold.
With the now defunct clay foot disposed off the latex was peeled away from the mother mold and the bag was removed as well. There was a considerable amount of adhesion between the surface seal of the clay foot and the latex mold despite the release agent used. In the past when making latex molds of sasquatch casts I've always applied the latex directly to the untreated cast with only a release agent, which leads me to believe it was the sealer that created the problem Regardless of this for the creation of TF1 it's a moot point since it will be sanded prior to being used.
(A little dust is all that remains of poor clay foot.)
With the now defunct clay foot disposed off the latex was peeled away from the mother mold and the bag was removed as well. There was a considerable amount of adhesion between the surface seal of the clay foot and the latex mold despite the release agent used. In the past when making latex molds of sasquatch casts I've always applied the latex directly to the untreated cast with only a release agent, which leads me to believe it was the sealer that created the problem Regardless of this for the creation of TF1 it's a moot point since it will be sanded prior to being used.
(A little dust is all that remains of poor clay foot.)
(The mother mold in all its glory.)
(Then they form up like Voltron.)
(Then they form up like Voltron.)With the mother mold now made and the latex mold cleaned up and ready to go the only thing left is to use them. Since TF1 needs to be durable enough for multiple uses I dipped into my stash of Ultracal 30.
(The genesis of TF1 begins.)
(The genesis of TF1 begins.)The Ultracal 30 was mixed per the manufacturer's instruction. Once the slurry was properly prepared it was poured directly into the latex mold.
(The genesis continues.)
(The genesis continues.)With the latex mold fully filled the next step can be accomplished. In the past I've embedded hangers into the back of the cast so that it could be displayed on the wall. Since TF1 will be used for test casts this wasn't neccessary. However, I did want an easy way to pull the cast out of the casting substrate so I decided to include a couple of handles in the back.
(Handle making Step 1.)
(Handle making Step 2.)
(Handle making Step 3.)
(Handles.)
Inserting the handles is a bit of a trick. The slurry needs to be soft enough so that the handles can be inserted but not so soft that they sink to the bottom. The bent ends of the handles are inserted into the back of the cast until they're fully submerged. The slurry is then smoothed back over the hole created by inserting them.
(Handle making Step 1.)
(Handle making Step 2.)
(Handle making Step 3.)
(Handles.)Inserting the handles is a bit of a trick. The slurry needs to be soft enough so that the handles can be inserted but not so soft that they sink to the bottom. The bent ends of the handles are inserted into the back of the cast until they're fully submerged. The slurry is then smoothed back over the hole created by inserting them.
(Handles inserted.)
With the handles set into the back of the cast there's nothing else to do but wait. Again, proper time needs to be allowed for the cast to fully set. Once the cast has fully set the last step is to simply remove it from the mother mold and peel away the latex.
(TF1 is born.)
(TF1 is born.)
And that's about all there is to it. From clay model I've made the transition to gypsum cement cast. In the next and final installment of the sub-phase I'll be preparing the surface of TF1 for the subsequent casting experiments.
