Rubber Molds & Green Stuff

Technically the title of this post isn’t entirely accurate but I’ll get to that in a bit.

Any one who’s read my previous posts will have come across my use of Blu-Stuff putty to make simple push molds and simple Green Stuff casts. Whilst I’ve found this immensely useful there are limitations. Because the Blu-Stuff mold isn’t very flexible it’s quite difficult to cast anything really three dimensional and as such most of my uses have been replicating surface details.

The answer to this is to cast with conventional silicone rubber and resin, allowing complete 3D replication. My two main gripes with resin casting  are the time frame with the silicone rubber curing and the general toxic nature of resin. When I managed to acquire a material I called Liquid Blu-Stuff it solved the issue to a long waiting time as it cures within about 20 minutes.

I’ve had some successful casts using this and resin, but my general unwillingness to use resin unless absolutely necessary has meant I rarely use this technique. What I really wanted was a quick and simple way to make Green Stuff casts but I couldn’t make it work with the Liquid Blu-Stuff because the Green Stuff was too firm.

So last week I came across a 2 part putty called Magic Sculp on eBay that advertised itself as finer than Mulliput (link here) that I figured I’d try it out as a Green Stuff replacement. I’ve never really been a fan of Mulliput and so haven’t used it in years. This product smells just like Mulliput and whilst I can’t offer a proper comparison, I didn’t find it suitable for miniature sculpting. So I put it to one side and never expected to use it.

Then I remembered being told of how some people had tried mixing Mulliput and Green Stuff (something I’d never tried because of my dislike of Mulliput). So I tried mixing this Magic Sculp with Green Stuff (in equal amounts) and I have the admit that I was really pleased with the results.

The mix is softer than regular Green Stuff and using clayshapers I managed to get some very smooth finishes, far smoother than normal. When using spit or water as a lubricant there is a small amount of residue from the Magic Sculp that ends up on the chapshaper when sculpting, which makes it a little messier than plain Green Stuff.

Getting back to casting… it suddenly occurred to me that this mix is softer enough to push into a Liquid Blu-Stuff mold without distorting the mold.

So long story short, I found a really simple easy way to duplicate components in putty. I suppose just using the Magic Sculp without the mixed in Green Stuff might work too, but overall I think mixing the two different putties results in a much more suitable material.

Moving on…

My first test piece uses the torso and arms from a Reaper Barbarian miniature that I bought ages ago and never got around to using. I wanted to try and use this torso on the plastic Bestigor models to try and give them a move muscular look. As you can see it’s a very nice chunky piece and I hope a nice fit for my Beasts.

After selecting what I wanted to cast I took a small pot big enough to fit the piece with room for a reasonable thickness of silicone around the outside of the component. I used a small piece of poster tack to attach it to the bottom of the pot. Knowing the pot to be about a 30ml volume I then took a small measuring pot.

I added 15ml of the blue half of the Liquid Blu-Stuff to the measuring pot, followed by 15ml of the white half. I then mixed thoroughly with a wooden stick until it was a consistent light blue colour.

Next up I slowly poured the mix into the bottom of the pot. At no point do I pour directly onto the component, instead I let the pot fill up from the bottom until the component is fully covered.

After giving the Liquid Blu-Stuff 20 minutes to cure I removed it from the pot, and making my best guess used a sharp scalpel to cut open the mold, trying to slice the mold open down the center line of the component (where you’d expect the mold line). I had intended to cut it all the way through but I found I could remove the original component without completely separating the two halves.

Next up, I cut holes in the top and bottom of the mold, connected to the hands, bottom of the torso and neck of the miniature. I also cut corresponding hole into the bottom of the original pot just as I would if I were going to fill the mold with resin. The plastic pot and the fact the mold is still in one piece rather than two mean the mold will go back together accurately.

Moving on to the putty mix. I mixed equal amounts of Green Stuff and Magic Sculp, trying to estimate that I had a bit more than the actual volume of the original component. I have tried altering the ratio of these putties but I personally find a 1 to 1 ratio to give the best feel. I invite you to experiment if you wish to try this yourself.

After mixing I simply push the mix into the mold making sure all the negative areas are filled. I then forcefully pushed the two sides of the mold together. The putty is soft enough that with enough force the excess mix is forced out of the holes perviously cut into the mold.

The mold is then pushed back into the original pot to force the mold to hold its proper shape and put pressure on the soft putty inside.

I left this overnight. I’ve so far forgotten to time just how long this mix takes to cure. The Green Stuff is normally 3-4 hours whilst Magic Sculp is roughly 12 hours, so I’d estimate about 8 hours for this mix.

The next morning I removed the mold from the pot and very easily opened the mold and removed the cast.

As you can see the level of detail in the cast is very high and there are no air bubbles (I also did a cast in resin and did get air bubbles). The flash around the edge is about half a millimetre thick. This is dependent on just how much excess putty is used and how much pressure you can add when squeezing the two halves of the mold back together.

Another advantage to the Green Stuff & Magic Sculp mix is that it is a lot nicer to cut and carve than just pure Green Stuff. I can’t say for sure whether Magic Sculp is equivalent to Mulliput or not (it smells the same) but I assume it is.

Next post I’ll show how I put this to use with my Bestigor prototype.