Well, I actually recorded the entire process. And am planning to upload it as a tutorial somewhere along the line.
. But until I get round to editing and voicing over it I guess words shall have to do.
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You are correct! Its a 2 parter, I was originally going to do a 1 but I've had bad experience with tearage so I thought I better not.
To start with I set up a clay divider, I guess a sort of channel thing around the entire mould And dented some keys into the channel to serve as keys into the other side of the silicone. This would also serve as the seam of the join. I then poured 200 ml of Silicone and another 200 just to get the surface covered (I used a paint brush to get into the details and avoid airbubbles forming. Next I used more silicone (can't remember how much) and mixed it with ground up silicone from an old mould (I use a meatgrinder) This works as a kind of filler and makes your new silicone go a lot further. Few layers of that, until all I could feel when I pressed on the silicone was silicone and not a hard clay underneath. Whew. Next was the mould keys. In order to do that I filled a cup with the ground silicone and then poured the new stuff in there, It bonded together and worked a charm. All you need to do after that is cut them up into qaurter circles.
. Bond them to the mould and that side was done. I try and spread the keys out around points that are likely to sag.
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I then peeled of the clay barrier and refined where it had sat. Peeled of the drippage of silicone that had gotten past my diligent eyes. From there I set up a new barrier of clay to work exactly like the other one. Just in reverse, This was a bit of a problem as the clay does not bond to silicone well, In the end I used Vaseline to plug up the edges. (worked a charm!). Then I just repeated what I'd done to the otherside, in reverse. Making sure to get all the details. Also should not that I used a mould release to make sur the silicone seperated easily.
Now The mothermould. I cut up an icecream container and used those pieces as shims. I slid them carfeully between the 2 pieces of silicone, but not too far, otherwise it will push apart the keys and make a massive gap later on. From there I lathered the shims in Vasaline (seems to be the only thing that really works for fibre glass).
. Then I fibreglassed that side. Let it set, reversed the mould, Trimmed the edges, pulled out the shims and fibreglassed the other side. Then, trim. Took ages to get it all done, but when I pulled the silicone off and saw how good it looked I was pretty happy, well worth it.
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Hope that was enlightening!
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Any questions? Don't hesitate to ask.
Cheers, Dave.
Don't know how long before the footage will be up, but I'll try and get onto it ASAP.