Forum adverts like this one are shown to any user who is not logged in. Join us by filling out a tiny 3 field form and you will get your own, free, dakka user account which gives a good range of benefits to you: No adverts like this in the forums anymore. Times and dates in your local timezone. Full tracking of what you have read so you can skip to your first unread post, easily see what has changed since you last logged in, and easily see what is new at a glance. Email notifications for threads you want to watch closely. Being a part of the oldest wargaming community on the net. If you are already a member then feel free to login now.

So I'm attempting to make some terrain for a competition over at another forum. If anyone is wondering I need to make 5 Gorinko:
http://en.wikipedia.org/wiki/Gorinto

So I first had the idea of finding a bunch of beads and sticking them together, but for my entry I am going to want them to look suitable ruined, and resin/plastic/wooden beads arent exactly the easiest thing to mangle, so I had the idea of making one master, then using air-drying clay to cast a bunch, which I can then 'distress' much more easily, and will also give me consistent results.

Does anyone have any experience/guides for the total newbie/suggestions on the subject?

Thanks

if you would mention a scale that would help

Air dry clay needs air to dry (shocking I know ), so if you are casting larger items with solid lumps of clay, you will find that it will not actually dry inside the mould. Use thinner layers of clay inside an open 2 part mould to ensure they dry.

I would use the beads...scratch them up by walking on them on concrete, or by rubbing with sand paper.

You can also always make them look "distressed" with the paint job...(lots of dry brushing). etc.

I do a lot of casting, but have never used air dry clay in that way so have no input there (its sounds difficult...but again, I have no experience in trying to cast with it...how would you even do that?).

davethepak wrote:I do a lot of casting, but have never used air dry clay in that way so have no input there (its sounds difficult...but again, I have no experience in trying to cast with it...how would you even do that?).

I've used both silicone moulds and re-usable moulds with air drying clay - it doesn't give a lot of detail and you have to use quite thin layers in order that the clay furthest from the air actually dries out in a reasonable length of time - ideally you want something less than 1cm thick, preferably less than 0.5cm.

Hydrocal/plaster is what you will want.

Most air dry clay will work OK for open faced molds (smush it in and then pop them out to dry) but for a more complicated mold like this - you are asking for problems.

Make your master how you like and do a mold (latex rubber works fine for plaster molds - and it is cheaper/easier to work with than silicon rubber). Head to a hobby shop that deals with trains - pick up a small carton of hydrocal and a bottle of your pigment of choice (they have pigments for most common stones as well as things like concrete). Mix it up per the directions on the container - pour and shake the bubbles out (I use a cheap sander on my casting table to vibrate it). Let it set up for a bit (over night is what I do - but you can actually strip the molds sooner - plaster container will have the details). Clean any flashing and proceed to weather/damage as you want to.

Once the plaster has fully cured, it is fairly strong. During the first few days after you cast it you can scratch and carve it pretty easily though. By adding the pigment to the mix before you cast, it ensures that you will be able to do damage to the cast object and the same color will be present all the way through.

I've used it to do very small details as well as things like walls for buildings as thin as 1/8" thick.

http://www.hirstarts.com/

They have all the information you need to know on their website (except of course how to make your master - you will need to sort that out yourself).

Thanks for the input guys, I'm a complete newbie to this casting stuff so all your advice is much appreciated

@Dijnsk - these are 30mm scale, gonna need to be about the height of a space marine I think.

I was thinking about making a two-part mold, mushing the clay into the mold, pressing the two halves together to create the model and then pulling it out to dry (seeing as how its a lot denser and more rigid than GS/Milliput/etc) but it seems that this is definitely not the way to go about things. My issue is cost more than anything, latex/plaster of paris seems a quite expensive set-up (the latex more than the plaster).

Someone on another forum suggested using Oyumaru/instant mold as the mold material, anyone have any experience with that?

As for weathering, I mean some pretty extreme weathering (breaking chunks off, maybe break one in half etc) which I thought would be ideal for clay, as it is a lot more brittle, but I'll be painting them so I am not so worried about pigments etc.

Leigen_Zero wrote:Someone on another forum suggested using Oyumaru/instant mold as the mold material, anyone have any experience with that?

Instant mould is pretty awesome, though don't rely on it for making 2 part moulds that you are going to be pouring resin/plaster into. You can make pourable 2 part moulds, but it works best with more viscous material as the IM can stick to itself when you make the second part, and also can be difficult to create a perfect seal between mould halves. 2 part press moulds are doable.

I find it works best by IM'ing one side of the object, cooling, then trimming the 1st half of the mould with a knife to get a lock and key type shape that the second half can fit over.

Then heat the second side and press to the object. When it cools you may find it has bonded to the first mould half, but you should be able to pull/cut it apart reasonably easily.

The problem can come when you push the mould halves together, the IM is not hugely strong and will flex easily, distorting your cast.

Leigen_Zero wrote:My issue is cost more than anything, latex/plaster of paris seems a quite expensive set-up (the latex more than the plaster).

Back when I was broke, poor, didn't have any money and all of that - I used to use latex caulk for creating the molds for small things like these (pillars, tombstones and the like). You do need to fudge with it a bit more than regular molding latex (the molding latex is generally thinner so it flows better) but you can actually get really clean casts from it for dirt cheap. I think a tube of cheap latex caulk will probably run you a dollar or so and give you enough rubber to create a dozen or so small molds.

You should be able to find videos over on YouTube that explain the various issues regarding caulk molds.

Even with the molding latex - you are probably looking at $10 or so for enough to make a mold of your face (or arms or some other body part). Between the coupons and the volume sales that are done for the people who like to do that sort of thing...it is hard to find a cheaper option.

The various friendly plastics (Oyumaru/Instant Mold included) have the problems which were mentioned by SilverMK2 - as well as a few others. If you build your master out of beads (or something like that) you need to make sure that they are solid and won't come apart easily. Although the stuff gets fairly soft, you still need to use a fair amount of pressure to get it into all the nooks and crannies to make a good mold from. Because of this, I wouldn't bother making a normal 2 part mold - rather I would just squeeze the stuff all around it in a single go. After it had set up - use a sharp hobby knife/scalpel to cut a slit on one side and remove the master. Since it is somewhat translucent - you can see the master through it and it is pretty easy to cut out.

However, holding it together tightly after the fact for casting is a PITA. You won't have a mold box to do that for you - so you have to figure out some way of clamping it with rubber bands or something (less problematic with a single seam than an actual 2 part mold...but still, annoying).

Air drying clay really isn't ideal for this.

Make a master.
Make a 2 part flexible mold.
Band and brace your mold together.
Pour Plaster of Paris into it.

You can make your master out of air drying clay.


As long as you avoid overhangs you will be fine.

Cheapest flexible mold material that I know of that works well if 100% silicone caulking mixed with Corn Starch in a 50/50 ratio. Makes a putty that will hold detail well and is about $4 in materials.

Plaster of Paris is the easiest and cheapest casting material you will find. You will also be albe to easily carve into it to distress it.

Just got this e-mail from Hasselfree re thier sculpting comp -
2: The Final piece must be able to be castable in metal by us. This means you will need to use epoxy putties like Greenstuff or Milliput plus you can add other items like guns or parts of other figures. Fimo is not advised as it can crumble under the pressure exerted on it when a mould is being vulcanised.

Spincasting, like Hasslefree would use, involves vulcanized rubber molds. Vulcanized rubber molds are heated and you squeeze the master into them. It's brutal on the master, requiring them to be able to survive lots of heat.

It's entirely not the tech you would use to make a half dozen small terrain pieces for yourself.