Mold growth. . .

. . .O.K., so actually a better name for this would be mold deconstruction (the reason for which I'll get to in a second) but that doesn't sound as catchy. I have to put in a disclaimer right from the start: This is in NO WAY intended to be an instructional on doing a mold. I actually hesitated to even include these photographs for fear I might get an angry email from someone telling me how they destroyed their sculpture trying to use our "technique." My Father learned moldmaking from various people, umpteen years ago. I learned everything I know (And I'm STILL learning) from him. This is NOT the best way to make a mold. . .this is just how we do it. We are entirely aware that there are many different materials and methods out there that could make the whole process go smoother *but* this is what works for us and we have stuck to it rather than risk an accident while trying to experiment with something new.

Anyhow, I'll do my best, as I go, to answer the questions that I'm guessing you might have while looking at these pictures.This is the clay sculpture covered with the flexible silicone mold. The layers are carefully applied one at a time, allowing them to cure between coatings. We alternate colors to ensure an even coat and usually do 6 layers or more.
I have to apologize for the fact that I have no photos of the plaster mold going on. . .just photos of it coming off. Admittedly, I am a total nutcase during moldmaking and my nerves kept me from remembering I was supposed to be documenting this. :^\ Why so nervous? Wellllll. . . I've heard a LOT of stories from Dad about all the things that can go wrong and, even though he has a magician's touch with getting things to work even in the most dire of situations, I always have the fear that *this* time everything is just going to go KABLOOEY!

Yes, those are the magic artist hands up there in that pic. That block o' stuff on the horse there is the plaster mother mold. It gives a rigid backing to the flexible inner mold so that anything cast in it comes out shaped like it's supposed to and not like some sort of funhouse mirror version of the sculpture. The plaster is put on in four main sections using clay walls to contain each part until the plaster dries. (I am *really* sorry I don't have pics of that, it'll have to remain a mystery until another occasion arises to make a mold) Needless to say, it's an incredibly messy process that ends with everything and everyone covered in plaster and pottery clay.

In this photo the first quarter has been removed. The brown stuff around the edges of the horse is clay left behind from the wall that supported the plaster on the opposite side before the final quarter was done.
Front half of the mold successfully removed. *whew* There is potential at this stage for the mold to lock up and refuse to come off smoothly so it's always a welcome sight to see things coming apart relatively easily!
No, your moniter doesn't need adjusting, it really is pink. We brush the whole piece down with a parting agent to help the mold come away from the silicone and keep the plaster sections from sticking to each other. Because we end up with what is essentially a big lump of plaster when the mother mold is complete, the color is added to make it easier to find the partings between the sections when we first remove them like we are doing in these photos. Scrape, scrape, scrape. . . look for the hairline of pink color. . .insert knife edge. . .tap tap. . .pry *gently* apart.

Pulling away section number three. Almost there!
This is good. . .everything came off o.k. with only a tiny bit of cracking in an inconsequential spot.
THIS is why I am an anxious mess while the mold is in process. When you use a soft oil base clay, your original is destroyed. If something terrible goes wrong with the mold (and it hasn't yet at least not where all was lost) the sculpture would be a total loss. Back to the sculpting stand, do it all over again, completely blow your deadline and any deadlines anyone else has riding on it. . . this is why I wish I could be tranquilized through the entire molding process.

The back half, removed from the clay, scrubbed and ready to cast into. What? Hmm? Why is it cut in half? I'm glad you asked! Our molds are made for wax casting to be used for lost wax bronze casting. To make bronzes that are hollow inside, you first need waxes that are hollow inside, and the only way to do that is to cut the sculpture up so that hot wax can be poured in and then poured out again. For a small piece like this, cutting it in half is enough. . .a larger piece might be cut into as many as 6 separate pieces. . .Wazzat? Oh, you're wondering why I've got a wax pouring mold made that's going to give me half horses when what I really needed was a resin casting mold that would produce it all in one piece?
Yeah, remember in the beginning when I said this was just how we do it? Yup, if it ain't broke, don't fix it. ;^P It turns out that we can pour casting resin into these molds too. So, even though this horse isn't destined to be done in bronze, the mold will still do the job.
Right here. . . the moment I can breathe easy. One hard copy, in hand, a good casting. I'm finally relaxed for the first time in more than a week. Look at the mess he's laying in though! It was a rough time bringing him back into the world in this new form!