Casting Resin

[Furt]

I am considering venturing into casting with resin, a scary and possibly quite costly area of terrain making.

Can anyone tell me what type of resin is used in a lot of commercially cast terrain pieces, the gray stuff in particular?

Alternatively is there some other product backyard mold makers use?

I am looking to do this as cheaply as possible.

[Major Weenie]

Don't know how helpful this will be, but here goes.
My local hardware store tends to sell two types of resin.  Casting Resin, which I suppose has some advantages when used to cast 'things' and Laminating Resin which isn't as good in casting as CR, but is used to laminate fiberglass on boat hulls, etc.
The downsides of using resin, for me, are;
Resin is thick, so it doesn't flow into especially thin parts of your mould, and bubbles tend to stay inside and not float to the surface.  Perhaps you might try non-expanding urethane (sometimes spelled eurythane).  It's reasonably priced, compared to the cost of the silicone moulding compound it's frequently used with.  Try looking up a company named Silpak.  They're here in the US, but might ship overseas, or even have a local distributer.  I'll use resin for stuff like boulders, but not to cast up sombreros, kepis, etc.
Resin is not so great to sand.  Our local group has sollved that problem by using something we've named Hooverite.  (Because the chap who invented the technique had the last name of Hoover.)  Track down some ceramic automobile body repair putty.  In the US it's usually refered to as BONDO, but that's a specific product name.  Bondo is ground up ceramic suspended in resin. If you haven't used it, it's around the consistency of butter, you mix in a catalyst, and it sets up pretty fast.  But you couldn't cast with it.  To make Hooverite you buy a can of Bondo, buy some resin, pour the resin into the Bondo, and stir it up to make 'Thinner Bondo.'  You can use the same catalyst that comes with the resin to harden the Hooverite.  I sometimes mix in the Bondo catalyst as well, not becuase it makes it set up any faster, but because the color of this catalyst helps indicate when I have the Hooverite fully mixed.
How do you intend to make your moulds?  If you're just thinking about rocks, etc. you could use 'Press Moulds' created by pushing a master into sulfer free modeling clay.
Hope that this helped.
Regards,
Maj. Weenie

[rjandron]

Resin for terrain pieces can be quite expensive, since you're putting in a lot of resin into a typical terrain piece.

I would recommend looking at products from "Smooth-On", which features resins that can flow like water into molds, as well as many other viscosities. If you want to start experimenting with resin, you can always try Alumilite, which sells resin casting kits in many hobby shops in North America (not sure about elsewhere). Alumilite is a thicker resin that flows like honey.

If you plan on working with resins, make sure you take appropriate precautions. Some resins can give off toxic fumes as they set up, so working outdoors or in a well-ventilated area is crucial--and good practice in any circumstance where you work with chemicals. I'd also suggest using a vibrating table to help loosen up air bubbles that may work their way into the mold as you pour the resin--it's not as effective as (nor as expensive as) a vacuum chamber, but it can help.

Molding compound can be acquired from Dow Corning, Smooth-on, or Alumilite.

I've played around with Alumilite, creating masters from Super Sculpey and molds using alumilite molding compounds, and had fairly good success with it--even with fairly complex 3-part molds.

To get the best value, you're going to have to buy resin and molding compounds in bulk. Even so, it can still get pricey.

One other option you may want to look at if you are casting terrain pieces, is to use Plaster. Check out Hirst Arts for tutorials on plaster casting. Plaster of Paris is dirt cheap, especially compared to resin, and works great for thicker castings. Or you can try harder plasters like Dental Plaster.

Have fun!

[Skrapwelder]

I'll second the recommendation for Smooth On resins. The quality and consistency are well worth the little extra you will pay.
Here is the web site for their Australian distributor. I use the Smoothcast 300.
http://www.rowetrading.com.au/

You can lighten your pieces reduce the amount of resin in a casting by using an extender make out of micro bubbles. The Smooth cast 300 costs about $85.00 for a two gallon kit. (1 to 1 mix ratio) from my distributor in the states. A gallon of two part mold rubber runs about $120. To give you an idea of resin yeild, I can get about 14 buildings like this out of a two gallon resin kit.

The building measures about 3.5x8x7 inches.

Hope that helps.

[Ramshackle_Curtis]

I use polyester resin, the same as for fiberglass stuff. Its cheaper. Also I use grey pigment as it helps to see detail.

[Grekwood]

you may need a Polyurethane Fast Casting Resin with Polyurethane black pigment....

not done any commercial resin casting yet...but the best stuff we've used is the G6 urethane Biresin from Tiranti, a 2 part resin which is Very fluid, with an easy mixing ratio (1 : 1) and very quick setting, it has a 5 minute pot life and a 30 minute cure. It's a cream colour...to make it grey we just add a small amount of the black pigment.

a couple of commercial wargames resin casters in the uk get their stuff from Mouldlife but they don't deal with individuals at present..

[Hammers]

I've always heard that for a quality job you need a vacuum chamber to get the air out of the resin. Is this true+ And here could I get an affordable vacuum pump for hobby use? (No smutty replies please...)

[Grekwood]

I've always heard that for a quality job you need a vacuum chamber to get the air out of the resin. Is this true+ And here could I get an affordable vacuum pump for hobby use? (No smutty replies please...)

yes..vacuum moulding/casting does give better results.....although it's also depends on the resin used, mould quality, size of casting etc.....i've never used a chamer and so far had good results with the biresin, although most things we've cast are small and chunky so they tend to cast quite easy and bubble free.

if you can afford a chamber, have the room for one and are thinking about commercial casting...i'd say get one......trouble is they tend to be quite expensive

[Dewbakuk]

If you're doing anything complicated or with lots of detail then really you need a vacuum chamber. Also if you're casting commercially and getting saleable casts every time matters then you also need a vacuum chamber.

Cheapest one I've seen recently was £400 for chamber and pump, but that was second hand on ebay.

[Alfrik]

When I cast resin into my mold the first cast shows where the bubbles are most likly to form, so I use a 6inch long copper wire, very heavy guage, with the tip filed smooth to run around in the mold to chase the air bubbles out. Just an idea of how I do some of my casting, especialy for figures.

[Cheeky Monkey]

One company that I haven't seen mentioned is Micro-Mark -
http://www.micromark.com
they have mold making silicone as well as casting resins. While I have never used their casting resins I have used their 10:1 mold rubber and it works just as well as the Smooth-On product although it is a bit more expensive - it seems to me to be basically the same product. I would stay away from their 1:1 silicone as it tends to be too brittle. And they ship world-wide! I have talked to others who have used their casting resins and have been told that they work well even without a vacuum chamber. You just have to be careful which resin you use - longer pot life = fewer air bubbles - generally speaking.

[Sangennaru]

I'm from Italy, (the really other side of the world, for you), but I'm pretty happy using PROCHIMA SYNTAFOAM 1.1

it is more fluid than honey (like olive oil) and I hardly find bubbles in my products. It is pretty expensive (around 100 - 110 US$ for two gallons), and I'm looking for a cheaper one for cheaper casts and less detailed parts...

I'll follow this topic, if someone has also suggestion for me, I'm also into this stuff since a short time!

[Major Weenie]

I actually posted this image earlier when someone was asking about 'Bell Tents.'  Here it is again, with a pair of Wagames Foundry figures in frame to give scale.
It's cast out of 'Hooverite' the mixture of Bondo and casting resin that I mentioned in a previous post.  It's a simple 1-piece 'Drop Mould' without any bottom.
When I read the first post I thought you were considering methods to cast up hills, rocks, etc.  But it seems that you might actually be interested in buildings.  If so, my recomendation would be to construct/sculpt the front wall of the building lying flat on its back.  It wouldn't be very thick, and you could them make a drop mould of that.  Then cast it up, pop it out of the mould, and tilt it up to vertical for the front of your building.  If you were making row houses then you'd only need to make moulds for the house fronts.  If you were really energetic you could make multiple moulds for several fronts, backs & sides. Then mix and match them.
Helpful-Maybe,
MW
PS - I still haven't looked up the web site for Silpak, which is the two part casting urethane that I like best.

[Donpimpom]

I'm sorry to raise a dead thread, but  I though it's better bump it to avoid redundant threads.

I'm thinking also to get into resin cast, I have read is better to use acrylic resins than polyester resins, they don't release toxic vapours, they are less aggressive with the silicon mould, and because they are water based it's easier to clean the tools.

Seems acrylic resins are all advantages, but as far as i see everybody is using other kind of resins.
Anyone has experience on acrylic resins? is any difference on detail level  and viscosity between each type of resin?

[FramFramson]

I haven't done anything with casting since plaster skulls in university, but I do remember a very nice article on the subject of eliminating air-bubbles and the like.

Rather than using an expensive vacuum pump, you can build a rotocaster. It's not as good as a vacuum pump, but can be built quite cheaply and still gives you a lot more options and better mould penetration that you can get with plain regular sit-n'-pour.

It was an old ShiftingLands article and can be found here