Okay, so after a first failed attempt, I'm about to go for round two of molding my clay-sculpted helmet. Before I begin again I wanted to ask a couple of questions. During my first try I made the stupid mistake of wearing latex gloves, and there were a couple of little spots that didn't cure.
First off, is there a way to tell if I've cleaned the clay off well enough to try again without wasting another batch of silicone?
Secondly, during the first try I noticed that the Rebound 25 is a LOT thicker than I thought it would be. When I peeled off the failed mold, I got a couple of air bubbles on the surface. Because clay is so very prone to scratching, I am very hesitant about using a paint brush to get the print layer, so I was thinking of using a foam brush to spread the silicone into those hard-to-reach areas. Rebound being as delicate as it is, though, I don't want to use anything that might contribute to cure inhibition.
Third, I've gotten a few suggestions saying I should seal the clay, somehow. I've got some clear acrylic spray and some primer, but I do need to be able to re-use the clay, and I'm afraid those materials might prevent me from doing so.
Last thing, I need a good, cheap, readily available, idea for registration keys. I considered using keys from an old keyboard, but after pulling them out, I don't think they're going to work. I've seen Ben Streeper's video suggesting wads of cheese cloth saturated with more Rebound 25, but if there's something I can embed into the silicone instead (like Master Cheeze's ceramic keys, only available in my area) I'd prefer to go that route.
Really last thing, how do you get the "mohawk" parting seam in the mother mold to work? I tried this on a test mold with clay and strips of scrap plastic and had an absolutely terrible time of it. Do you embed the plastic strips into the silicone and leave them as a permanent parts of the mold? One video tutorial I saw said they should come out, but I'm not sure how you'd remove it at that stage, and it seems that leave a gouged line in the silicone.
Okay, I think I'm done for now. Any advice would be appreciated.
First off, is there a way to tell if I've cleaned the clay off well enough to try again without wasting another batch of silicone?
Secondly, during the first try I noticed that the Rebound 25 is a LOT thicker than I thought it would be. When I peeled off the failed mold, I got a couple of air bubbles on the surface. Because clay is so very prone to scratching, I am very hesitant about using a paint brush to get the print layer, so I was thinking of using a foam brush to spread the silicone into those hard-to-reach areas. Rebound being as delicate as it is, though, I don't want to use anything that might contribute to cure inhibition.
Third, I've gotten a few suggestions saying I should seal the clay, somehow. I've got some clear acrylic spray and some primer, but I do need to be able to re-use the clay, and I'm afraid those materials might prevent me from doing so.
Last thing, I need a good, cheap, readily available, idea for registration keys. I considered using keys from an old keyboard, but after pulling them out, I don't think they're going to work. I've seen Ben Streeper's video suggesting wads of cheese cloth saturated with more Rebound 25, but if there's something I can embed into the silicone instead (like Master Cheeze's ceramic keys, only available in my area) I'd prefer to go that route.
Really last thing, how do you get the "mohawk" parting seam in the mother mold to work? I tried this on a test mold with clay and strips of scrap plastic and had an absolutely terrible time of it. Do you embed the plastic strips into the silicone and leave them as a permanent parts of the mold? One video tutorial I saw said they should come out, but I'm not sure how you'd remove it at that stage, and it seems that leave a gouged line in the silicone.
Okay, I think I'm done for now. Any advice would be appreciated.
Fortunately, the Rebound 25 spec sheet says it doesn't need to be vacuum degassed, so I did something more akin to the "bombs away" method described in the video. The sculpt was on a low table, so I just poured it from a medium height. It seems to have worked, not much in the way of bubbles that I could ascertain from my inspection, but the real proof will be in the casting, so we'll see. As for the mohawk, I tried to get two thin sheets, as you suggested, but I couldn't get hold of two of anything large enough (I could have kept looking, but I'm two months behind where I wanted to be, and I'm getting impatient with myself). I tried cutting them into smaller strips, as I've seen in other videos, but after working for two hours I had too much trouble keeping them together and on the model at the same time, so I gave up and went with the single large sheet I found. Tonight I laid down a strip of thickened silicone and put the trimmed plastic sheet in it. I'll likely remove it after I put on the first half of the mother mold. Thanks for all your help!
