Looking for some molding suggestions and other considerations
in Sculpture
Hello all,
I'm getting close to wrapping up a piece that I want to cast in resin and I'm looking for some insight on molding.
This piece has a lot of fine detail and nooks and crannies and I'm not certain on how to approach the casting process. This is my biomechanical homage to HR Giger - the head, tail, and two smaller heads all detach. Some views for reference are below the text.
My initial thought was to do a brush on mold for the body with Rebound 25 and a support shell using free-form air. My thought was due to the small details and nooks, brushing in the silicone would be best so details were not missed (print layer), and bubbles were avoided, as well as saving a ton of silicone.
The head - was thinking a box mold, or potentially a two piece mold. The two piece mold may be overkill - I'm not certain - but I also wanted to have some practice at doing one. I thought I might be able to run the seam line along the base of the jaw and up along the midline raised rail. The two smaller heads and tail would be box molds.
I have a vacuum chamber and a pressure pot. I was thinking the pressure pot would be perfect for curing the resin in the mold due to all of the detail and potential for bubbles, but I've read you should have your silicone mold made under pressure as well to avoid micro bubbles/impressions on your piece when you get to curing the resin in the pressure pot. If I do a brush on mold, this step doesn't seem possible.
I see this piece as having a hundred different ways to capture bubbles, and have never seen anyone run vents on a brush on mold, so maybe box mold would be best.
My questions:
I'm getting close to wrapping up a piece that I want to cast in resin and I'm looking for some insight on molding.
This piece has a lot of fine detail and nooks and crannies and I'm not certain on how to approach the casting process. This is my biomechanical homage to HR Giger - the head, tail, and two smaller heads all detach. Some views for reference are below the text.
My initial thought was to do a brush on mold for the body with Rebound 25 and a support shell using free-form air. My thought was due to the small details and nooks, brushing in the silicone would be best so details were not missed (print layer), and bubbles were avoided, as well as saving a ton of silicone.
The head - was thinking a box mold, or potentially a two piece mold. The two piece mold may be overkill - I'm not certain - but I also wanted to have some practice at doing one. I thought I might be able to run the seam line along the base of the jaw and up along the midline raised rail. The two smaller heads and tail would be box molds.
I have a vacuum chamber and a pressure pot. I was thinking the pressure pot would be perfect for curing the resin in the mold due to all of the detail and potential for bubbles, but I've read you should have your silicone mold made under pressure as well to avoid micro bubbles/impressions on your piece when you get to curing the resin in the pressure pot. If I do a brush on mold, this step doesn't seem possible.
I see this piece as having a hundred different ways to capture bubbles, and have never seen anyone run vents on a brush on mold, so maybe box mold would be best.
My questions:
- Would I be better off doing the body in a box mold, allowing for as many vents as needed, as well as putting the silicone under pressure when making the mold?
- When putting a sculpt under pressure while making the silicone mold: do I run the risk of the sculpture collapsing under the pressure (this is sculpted in Monster clay medium)? I haven't seen anyone remark on this, and cannot find anything about it.
- Would a 2 part mold be a better approach for the body, and just box molds for all of the heads and tail?
- the nooks, crannies, etc. - are they going to post significant problems? I thought the brush mold approach might overcome this due to being able to apply thick silicone to any undercuts. I'm hoping to capture the fine details, and after a suggestion, have patched in some of it. But not a whole lot.
1
Comments
Any advice on release prepping?
It looks like you've already done a great job designing it to break down into more manageable pieces for molding, which is awesome.
Because of the body's complex shapes, I would do a brush-on "glove mold," which would eliminate any seams. Then, you can make any kind of rigid mother mold you like.
While brushing the silicone on you can also blow it around with compressed air, or even just blow through a straw to help push the silicone into deeper areas and pop any trapped bubbles.
Since it is a larger glove mold I would make sure to add lots of keys to help it lock into the mother mold.
For the head, I would do a 2 part mold with the seem right down the center. And if the details on the face are too complex or problematic, I might do a 3rd part to the mold that is just the front of the face and have the other 2 parts be the left and right sides of the rest of the head.
/Chris