Spear update
Sadly my Spear of Logius master broke demolding. It was "Stuck" pretty badly and I had to use a lot of flexing to pull it free. Now I know why. The brush on rubber was polyurethane based and I didn't use enough (or maybe the right kind of) mold release.
Parts of the Bondo "blade" coating the PVC core broke off. :(
The Bondo does not stick to the PVC sheets I got. I thought the Bondo would work better with the plastic. I guess it is just the wrong type. Next time I will use wood and use epoxy puddy for the inner core to add strength. I was avoiding wood because I was worried about the thin wood warping over time (mosture). But if it is properly sealed this probably won't be a problem.
The mold is crappy, only getting partial coverage of one side. But I am thinking I can cast a couple of partial blades and glue them together. Then sand and fill in the missing bits, building up a new master. Still a lot of work but less that starting from scratch. I could fix the damage to the master - but it will only happen again.
Not that I need the spear anymore with the game over. But I would like to finish it anyway. And it is a good prop to add to the prop box.
BTW - prop lady has a good trick for easy 2 part molds.
1 - make a box (I skipped this because I was using brush on rubber)
2 - fill the lower part of the box with a fast and disposable mold compound - In this case an alginate based mold cast you can get at the craft store.
Put some marbles or something in the edge for mold indexing. Let that set (it is quick) (Jut a quick way to fill the lower void space.)
3 - Do the top half of the mold in silicone.
4 - flip it over, remove and discard the disposable (it will probably have air bubbles and weirdness anyway) cleaning of any residue. (This should be a lot easier than removing the clay residue would be.)
5 - mold release, mold release, mold release
6 - re cast the explosed half in silicone.
I need to give this a try. It seems easier than building up a clay seam line. Especially later on when you don't have to clean it all away.
Parts of the Bondo "blade" coating the PVC core broke off. :(
The Bondo does not stick to the PVC sheets I got. I thought the Bondo would work better with the plastic. I guess it is just the wrong type. Next time I will use wood and use epoxy puddy for the inner core to add strength. I was avoiding wood because I was worried about the thin wood warping over time (mosture). But if it is properly sealed this probably won't be a problem.
The mold is crappy, only getting partial coverage of one side. But I am thinking I can cast a couple of partial blades and glue them together. Then sand and fill in the missing bits, building up a new master. Still a lot of work but less that starting from scratch. I could fix the damage to the master - but it will only happen again.
Not that I need the spear anymore with the game over. But I would like to finish it anyway. And it is a good prop to add to the prop box.
BTW - prop lady has a good trick for easy 2 part molds.
1 - make a box (I skipped this because I was using brush on rubber)
2 - fill the lower part of the box with a fast and disposable mold compound - In this case an alginate based mold cast you can get at the craft store.
Put some marbles or something in the edge for mold indexing. Let that set (it is quick) (Jut a quick way to fill the lower void space.)
3 - Do the top half of the mold in silicone.
4 - flip it over, remove and discard the disposable (it will probably have air bubbles and weirdness anyway) cleaning of any residue. (This should be a lot easier than removing the clay residue would be.)
5 - mold release, mold release, mold release
6 - re cast the explosed half in silicone.
I need to give this a try. It seems easier than building up a clay seam line. Especially later on when you don't have to clean it all away.