Tuesday, April 12, 2011

[Lantz's Corner] Casting Tutorial Part 1

Adorable As I Am, This Cute Mug Don't Pay The Bills

Hello again. It's time for me to start pulling my weight around here, so let's get to what I do best; tutorials. This will be a pretty long segment, and so, I'll be splitting it up into two sections so your bottoms don't fall asleep too terribly. These tutorials will cover a step-by-step process of casting resin models and duplicating them for your gaming pleasure. We've all done a conversion we wanted to duplicate without having to put another four and a half damn hours back into it. After starting my purchases of Adeptus Mechanicus models, I found myself more than stuck in this situation. It was finally time to dip my toe in the waters of casting, make the mistakes and learn from them. Now I'm here to show you the mishaps I've made so you can avoid them and get going on your own casts.

First, what you'll need. Casting being a complete mystery to me at the time, I asked John over at Dark Future Games for what to purchase. He suggested I use Alumite High Strength 3 for the cast which will be flexible and rubbery when dry and Alumite Regular Casting Resin for the resin models to be created (both look to have massive price drops from when I purchased them, you lucky sons of..) After getting these in the mail, it was time to get to work. The models I wanted to replicate are small in size, and so I would need a container for the silicone rubber to dry in. I've seen people use Legos to construct their container, and for larger molds you'll definitely want to find a solution like this. However, for the smaller models like the ones I wanted replicated, I went with the two dollar packages of plastic bathroom cups:

Now that we have the supplies we'll need (measuring cups and mixing sticks come with the rubber and resin kits,) it's time to choose a model to cast. For this tutorial I'll be using the Adeptus Mechanicus symbol found in the Manufactorum kit from GW. Be sure to cut, clean, GS and do whatever you want to your model before you get ready to cast. For the AdMech symbol I needed to cut the symbol out from the original model:

And while the intricate wiring and detail on this model is fantastic, it's not the style I wanted for the future projects I have (and the Manufactorum box comes with two of these, so I have a spare if I ever do want the wiring replicated.) So for this instance we'll need to GS it to get it the way I want:

Typically you'll want to glue the back of this symbol to the bottom of the plastic cup for the "below" method of casting. For this model, however, I'm going to be using an "above" method of molding to give you all an idea of what can go wrong. This means I'll place the model on top of the silicone rubber. Keep in mind this is not the preferred method of casting, but I'll touch on that in a bit. First, let's prepare the model for its endeavor. Once the model is placed in the silicone, I don't want it to sink into the mold before it dries, so we'll need something to hold it up. In this instance, I'll be using a plasticard tube glued to the model like so:
That's Right Ladies; Clean Fingernails. Try To Contain Yourselves.

And a clip to suspend the model exactly how I want it:

With that preparation in place, it's time to get a-mixin'! Let's grab our rubber base (the big tub) and get two measures of the rubber into a plastic cup, just shallow enough for our model to not touch the bottom of the cup:
This part can be a bit messy if not done carefully. Use one of the wooden sticks the kits comes with to scrape and slop around the rubber. This will keep your fingers clean during this whole process (and trust me, this stuff takes a while to get off your fingers, and unlike glue this sticky crap doesn't dry out.) The wooden sticks the kits come with are fine, but you'll honestly only get a couple uses out of them as the pores of the wood absorb the rubber and after one to two uses makes it difficult to work with. I ended up breaking the handle off of a plastic spoon instead which works wonderfully. Moving on, we'll take a tiny bit of the catalyst (the tiny bottle) and pour this into the rubber base keeping in mind the rubber to catalyst ratio is about 10:1 for your mix to come out correctly:

Now we'll mix the two together thoroughly. And I mean spend at least a full minute mixing this stuff. You don't need to worry about it drying out as it takes hours for it to start solidifying. Making sure this combination is thoroughly mixed together is an extremely important part of the process, so get your arm into it and mix like there's no tomorrow. Once your mix is ready, you'll probably have an abundance of air bubbles:
You'll notice if you take a minute that the air bubbles will pop on their own since the rubber is just dense enough to push itself down and air, up. You can wait 10-20 mins for this process to complete on its own since it takes a couple of hours for this stuff to actually start solidifying. To speed up the process of eliminating these air bubbles you can carefully blow into the mixture forcing more pressure downward. Take precautions when doing this as breathing in this stuff will give you a contact-high. And I'm not talking about the kind of high you get where Rachel McAdams shows up and wants you to take her back to your place, you'll just simply get a headache.

During/after the mix has settled, let's take a look at the model you're wanting to cast. Probably the most important task with casting is air bubbles and the steps needed to eliminate them. Taking the steps necessary beforehand to prevent air bubbles will save you a lot of hassle later on. Lest you want to GS your model over and over filling gaps...
I Don't Want To Talk About It...

For the symbol I've GSed, there's not much work to be done here. There's a huge potential for an air bubble in the skull's empty eye socket exampled here:
This is the disadvantage to the "above" method of casting. When you place a model on top of the rubber, your chances for air bubbles are increased substantially. I wanted to show this method to show you all how this can be avoided, though, so here's how to go about it.

Identify potential air pockets before placing your model in the rubber first, then take dabs of your rubber mix and fill these problem areas like so:
After pre-filling these problem areas, it's time to place your model in your mix. When doing so it's okay to move the model around and tip the cup in all directions so you're assured little to no chance of air bubbles. Let the cast sit for about 6-12 hours depending on how full your cup is, you silly optimist, you.

At this point (hoping you're reading this entire tutorial before attempting your own,) let's touch on the do's and don't of casting.

#1: Pewter
First, I want to get something out there. Do not attempt to cast pewter models. The rubber silicone will bond to pewter like nobody's business. I almost lost a pewter model to this discovery; spending the 4-5 hours of cutting, shaving and dremeling the crap out of it was not my idea of fun. You may be able to coat the model in something like soap, but I have yet to experiment with this. Until someone speaks up about a way around this I would not recommend attempting it.

#2: No Way Out!
Placing your model with no way out (like in the above image) means you will have to cut into your mold. This can be dangerous to your model as you'll need a very sharp tool to easily cut through the rubber and thus chance damaging the original. You can use this method if you don't give two pickles about your original, but keep in mind that cutting open a mold can get quite messy when it's time to pour the resin in.

#3: Pink Pants Of Doom
Gluing the model's feet to the cup is the right idea for the "below" method of casting, but here's the problem with the example above. The pink area between the legs (/giggle) and, depending, the armpits will prevent the whole model from getting out without some cutting. As mentioned above, cutting is bad. Essentially, you'll have your mold wrapped around both legs like an incredibly large and durable pair of pink pants. I don't know about you, but I've never been able to take off my pants through the hemmed butt. If you've done this however, please email me your mysterious ways of pant evasion. A similar issue occurs with the next Don't.

#4: I'll Never Let You Go!
The meltagun beautifully (cough) illustrated above has a "power cable" in its design. Just like the previous Don't, you're going to have your rubber mold wrapped around the tube in its entirety. If you attempt to pull the model out of the mold using shear force, your hose will break off (I chose my words carefully on that one.) The thing you need to understand before getting into this project is that the solidified rubber mold is strong. Ridiculously strong. Easy to cut through, but nearly impossible to harm otherwise. You can stretch one of your molds over your fist and the mold would still hold its original form when you take it off. This stuff is tough. So how do you solve this problem?

#1: Less Friction Can Be A Good Thing, Fellas
The easiest way I've found is to use a thin layer of GS around the problem areas. Keep in mind the solidified mold will be very flexible. You'll have some wiggle room to get your model out. But in the end, the easiest times you will have getting your models out from the mold will be if they're as close to a triangle shape (large end being the exit) as possible so when removing the model from the mold you'll have little friction to deal with:

#2: I Am Batman
Keeping this in mind your models will need some GS help like so:
As I said before, you'll have wiggle room with this flexible mold. But try and get as close to the triangle shape as possible using GS. When casting new models, you'll simply have to cut/shave the previously GS flaps, so the thinner you can make them the better.

#3: The Lizzy Borden Method
Another alternative is splitting up the parts of your model when it's possible. This will cut-down on and often eliminate the need for GSing as shown in the examples below:

Now that you have a basic understanding of the Do's and Don'ts of your mold, let's check back with our AdMech symbol:
On this attempt, I think I may have added a little too much catalyst as after 12 hours it's still a tad sticky. It happens to the best of us, don't judge me. If you ever run into this problem, have no fear. So long as your mixture was very thoroughly mixed, if you ever add too much catalyst just give it more time (this attempt took an additional 12 hours) and it'll eventually solidify completely. The only times your casts won't dry completely is when there's either too much rubber or it's not mixed thoroughly enough which will cause splotches of white (the rubber) in your cast; those will literally never dry.

So after additional time, our cast has dried! Let's get that thing out of the cup. Simply cut a bunch of slits into your cup (careful not to cut your cast):

And peel the cup down like a banana:

Now that we have an AdMech lollypop (The Magnet Pro is not responsible for the aftermath of licking casting molds,) it's time to get our original out of the cast. Again, your cast is tough. Run this thing over with your car and it'll still hold its shape. So if you need to be a little rough with your cast to get your original or self-casted models out, don't be shy about it. This stuff can handle anything you can throw at it with your bare hands:

A little hint for those that will end up using GS on their casts; the cast can sometimes bond to GS. Sometimes it does and sometimes it doesn't. For the life of me I can't figure out why it's so fickle, but worry not. It doesn't bond to GS like it does to pewter. Simply be a little more rough pulling your original from the cast when casting GS than you normally would be and your original will come out just fine, though you may have a little bit of cleanup work to do on the original:

Now, let's look at the cast. You'll notice the disadvantage of the "above" method of casting in the picture below. There is an abundance of little air bubbles across the flat surface of the symbol's indention. This will merely mean I'll have some filing to do when I make my resin models from this. However, for you Dark AdMech players out there, this could look a bit Nurgly.
You'll also notice the eye socket came out beautifully thanks to the steps we took earlier on. That will save a lot of work in the future casts I make from this. Once you've got the process down, you'll be making molds for all manner of bits and models!

And that's about it for Part One of this tutorial. In Part Two we'll take a look at using the resin for your casts so you all can start duplicating till your heart's content. As always, if you have any questions feel more than free to either comment below or email me at Sinaura40k(at)gmail(dot)com.

TLDR Version: You are doomed. Go back up and read the post again.

More on the horizon, stay tuned!

~Lantz aka Sinaura


  1. For starters into casting you should really recommend a 1:1 mix ratio silicone. It has no problems adhering to pewter like improperly mixed 10:1 silicone can. Also- if you're having issues with ANY silicone sticking to your original- you need to study up some on your technique. A light coat of mold release agent will prevent that issue, and for anything thats pourous, such as a plaster original, can be 'sealed' with a casting sealant or good coat of polyurethane spray(or even a light coat of spray paint).

    Using an entire cup for something as small as a single weapon....thats using alot of silicone thats essentially wasted. This is why alot of semi pro casters use legos to make mold frames. They are cheap, easy to use, and let you control the size of the mold you're making. Silicone on the other hand- not cheap at all.

    For air bubbles- theres several methods. Always pour it into the mold with a thin stream from several inches up- this is the first step as the thin stream will pop most bubbles in the mixed silicone. Next, is to let it flow from one side to the other- keep your thin stream pouring into the same spot-try not to move it around as this can cause the pouring silicone to fold and trap air.

    The way you filled in the eyes on your samples is a good start- but you can go one step further and use a small peice of foam dipped in the silicone to cover all of the fine detail and recessed areas with the silicone. To help even more-using a light dusting of talc powder on the original will help wick the liquid into the recesses.

    If your cast items have holes in them- thats from air bubbles formed from poor casting technique-air bubbles trapped in the resin because your mold designs dont have a way for the air to flow out as the resin flows in(this is why many use pressure chambers). If your casts have little blobs or bumps on them, thats from air bubbles in the silicone.

    There are dozens of molding videos on youtube these days. While most are not geared towards smaller items like minis, the fundamentals involved are the same and theyre worth checking out. Casting is time consuming, often frustrating, and it is not cheap. The time a good caster will put into learning the tricks is more than most people are willing to devote since it can be more involving than almost any other advanced modeling skill to learn. Its a pretty steep learning curve that usually takes a few batches of silicone to figure out.

  2. Use a spray lubricant to allow your master to separate from your mold. It'll also reduce the micro airbubbles you get across flat surfaces.

    The only reason you were able to even pull your master piece out of the casting rubber is cause it was a light grade silicone. If you used any regular strength casting rubber like the standard RTV (Room Temperature Vulcanizing) that master piece would be stuck forever in your mold and you would have ripped the mold apart to get it back out rendering it useless. Use something like this: http://www.smooth-on.com/Release-Agents-and/c9_1123_1226/index.html

    Pigment your resin before you pour and you'll eliminate 80% of your air bubble problem. The pigments thin the resin to a water like consistency and they diffuse bubbles on contact.
    like this: http://www.smooth-on.com/Urethane-Plastic-a/c5_1119_1213/index.html

  3. This is splendid. I have never been courageous enough to work with resin, but this tutorial is a great step-by-step guide for beginners. I will be linking this from my blog.

  4. Hi there, wicked article, theres not enough out there on casting.

    If I might suggest two things?

    the first is an explanation - the reason is sticks like hell to pewter and occasionally to GS is to do with the porosity of the surface, all the tiny, alomst imperceptible surface bu,ps of pewter, and sometimes GS, allow the silicone to grab like a tick.

    the way round this is tu use some for of mold release, you can buy them, or use silicone safe lubricants of various kinds :)

    second point, you didnt mention in your "how to cast difficult shaped objects" section the possibility of a two-part mold.

    say for the melta. use the "from above" method you describe with the melta half submerged, let this set, then using a mold release, pour more rubber, what you will be left with is a two part mold. now it's advisable to include things like siting pins/holes s the two halfs match up, and a pouting channel and vents, but you could cut all this in after if you really wanted :)

    anyway, brilliant article, and I will indeed stay tuned

  5. The above method should be considered a method. It´s illogical to have the model above, considering that the silicone curing process produces air bubbles, and they go UP. The model MUST be above so that the bubbles don´t mess with you. Also, for better avoid of bubbles, use a vibrator (no, no *that* one xD)or punch the table for some minutes, to create some vibration and get rid of most of the bubbles.

    I'll be waiting for the second part, would like to see how you manage to solve your problems and hopefully explain some new things ;D

    I've done a tutorial about resin moulding casting on my own, but new approaches are always welcomed ;D

  6. Im rather curious why my comments werent approved from my 6 am reply? Too critical?

  7. damn, typo again.

    The "above" method SHOULD NOT be considered a method...

  8. @Mistress of Minis - Nope not to critical at all. In fact Im sure Lanzt will love the advice from you and others.

    Sometimes when I approve a comment it takes awhile to input. No idea why.

    @everyone else :) - Keep in mind the tutorial part 1 and tomorrows part 2 are from the point of view of a beginner. Not a pro. There are way to many pro tutorials out there that are far to complex for someone just starting. These 2 parts are perfect for someone learning the trade :)

    Lantz is a natural, lets all sit back, relax and enjoy the show :) And I know for a fact he thanks you all for your feedback, so keep it coming!

  9. Very helpful commentary, thank you. As I mentioned in my post I'm completely new to the process and didn't have much to go on. Also as mentioned in the post the "above" method is not the way you would typically want to go because of... well, the problems I mentioned in my post.

    These comments alone have given me so much more info than I had before, thanks to all of you. Just be sure to pour a tiny bit more time into actually reading the whole post before making commentary. ;)

  10. @Mistress
    I forgot to mention I've never used a whole cup for one weapon. I'm not made of money! The illustration above was used to show the issues with getting models trapped, nothing more. (I should have noted on this in the post, but seeing as it was a novel as it is, I left a couple of lesser items out hoping common sense would be used to a certain extent.)

    I would actually recommend using the top and the bottom of a mold to get full use out of it when possible. Though keeping a good amount of space in between each model so you never end up with a meltaflamerplasmagun attached to a tail is a good idea.

    Again, thank you all for the new hints!

  11. clay is my favorite meathod. SULFUR FREE CLAY!!!!! or else watch the chemical reaction ruin your model and mould.

    it will be in the section with mould suplies in your local hoby loby/ suply store.

    Push model bases or ETC into them and it's my favorite way. It will give a flat base with limited smoothing for those two types of models.

    This symbol alone was why I started looking into how to caste. I am looking foreward to titan converting. This is my key.

    My other newely revisited passion is terrain building. Bunkers and modular fortresses are fun, but this above meathod will work for pllascrete texturing as I apply stucko to my models for that sandable finish.