Thursday, December 8, 2011

Necron Terrain: Mold Making Failure & Success

Progress on my Necron blocks has been slow going over the past several weeks.  My wife lets me do some modeling in the house, but for all the really messy stuff (sand blasting, pouring silicone and plaster) I have to work out in my garage with just a tiny space heater.  Lately most days have been below freezing and my little heater just couldn’t get the garage over 45 degrees, which is too cold for either plaster or silicone.  I did manage to sand blast my second set of masters though.  I used a Badger 260 mini-sandblaster with 220 grit aluminum oxide abrasive.  The blocks came from the printer with a fairly grainy surface to start with, so I didn’t have to hammer the plaster copies too much with the sand blaster.  Mostly I went for just rounding the corners and pitting the surface.   I experimented with some really harsh sand blasting but it was hard to control and tended to eat away at the faces more than the corners, making the blocks look more like melted butter rather than sand blasted.  I sand blasted three full copies of the masters from the first mold and picked the best to make my final mold.
I had the blocks all prepped for molding for a week waiting for it to warm up.  It’s been super frustrating and when I finally did get a warm day to make a mold of my new blocks I rushed it and didn’t de-gas the silicone resulting in bubbles in the mold.  Bummer, there’s $20 of silicone down the drain.
So I had to wait a few more days for warm weather and re-poured the mold and got it right this time.  I took my time and de-gassed the silicone and got a great looking mold with good fidelity to the blocks.
I cast this a few times along with Hirst Arts mold #93 (Egyptian Tower) to make the first test piece shown below.  It’s tough to tell without paint and weathering, but the surface textures between the two molds are pretty close.  The proof will be once I get it painted and stained this weekend.  So far, the results have been better than I expected.