Resin Casting Tutorial: Part II

(versión en Español)

PART I
PART II
PART III
PART IV
PART V

Hi again:

We saw yesterday how to make the first half of our two-part mold.

Once 24 hours have passed, it is time to put the mold upside down and remove its bottom.

This is how it looks. Now I remove the excess of silicone (you can save it for later recycling) and the casting frame.

Now it looks cleaner.

I remove the plastecine used to mask the parts we did not want to include in this half (Don't use for this anything with a cutting edge or you could damage the mold).

I clean any plasticine rests with rubbing alcohol and a tissue.

Now I put the piece back to the mold and rebuild the casting frame.

I add a demolding agent to the silicone. This is to avoid that the silicone that I am about to pour reacts to the first mold half, forming a solid block with you model in the middle!.

I use 5% vaseline disolved in 95% white spirit, so I let it dry before pouring the rest of the silicone. You can also put a little blob of vaseline, heat it with a hairdrier and spread it with a brush (pay attention to not damage your model with the heat). In any case, you don't need to apply vaseline to the model, just to the mold, as it can obscure detail.

The rest goes exactly as in the other half. "Paint" the silicone.

And pour the rest.

Now we must wait for further 24 hours to let the mold cure.

In the meantime, we'll learn how to do a vibrating tray to avoid bubbles during resin casting.

NEXT

Resin Casting Tutorial: Part I

(versión en Español)

PART I
PART II
PART III
PART IV
PART V

Well... Yesterday you saw a custom resin tank. But, the original model has to come from somewhere, isn't it?

The model used to make the silicone molds is called a Master Model. I did it using scratchbuilding techniques (that will be discussed here later on), divided in some basic parts and cast them separately.

Now I going to show you how to cast one of those parts, in particullar the hull piece of my KV-II like futuristic tank.

First, we must be completely sure that the piece we are going to cast is completely airtight. That mean that you must close all little gaps or cracks before starting. Once everything is ready we'll start making a mold from our original piece.

I am going to do a two-part mold, so I start making some masking with plasticine (modelling clay). I use rubbing alcohol (isopropilic alcohol) and a soft brush to clean and seal the joint betwen the model and the plasticine.

I put the plasticine covering the lower hull and making a gentle slope (you'll see why later). The mold line will be at the same level of the plasticine, so be careful when where you put it.

I also add four small stumps using more plastecine, this will serve to make the two halves fit once the molds is ready.

Then I build a box around the model and seal it with more plasticine (those are casting blocks that I got from www.hlj.com, but you could use Lego blocks, plasticard, wood, etc...).

This is the Room Temperature Vulcanizing (RTV) that I use. I get it hera, at Spain, from www.feroca.com, but you can buy similar products locally. RTV means that the silicone cures without need of heat (wich would be fatal for our litte plastic model). The small flask is the catalizer, you add it at 5% of the silicone weight (that means, you add 5 g of catalizer for each 95 g of silicone). I recommend you to have a spare bottle of catalizer around, as you normally use more than you really needed.

You can also see that there are some silicone chunks lying around. those are old molds that I am going to recycle. I will use also a handy disposable brush (those little thingies are very useful, come in great quantities and are dead cheap. What can I say?)

I weight the silicone and mix the catalizer.

Now I do some evil things to the brush. I bend the point and cut the bristles. This is to fix the bristles in place and make it easier to access to difficult places.

Then I add a little silicone to the mold and reserve the rest.

I use the brush to force the silicone into difficult places and remove superficial bubbles.

It's a bit like painting...

Now I start recycling all those old silicone chunks.

I simply push them carefully in the mold, to be later covered with more silicone. Once the silicone vulcanizes it will become a solid piece... So, just don't throw away old molds. Recicle them!

You can see all the bubbles raising to the top. Now, it's time to put it in an even surface and let it cure during 24 hours.

As this is real-time, we'll have to wait until tomorrow (or later, as I simply run out of silicone) to continue our little tutorial. Next day we'll learn some things about demolding agents and how to produce the second half.

See you...

NEXT

Soviet-themed wargame army

(versión en Español)

Hi you all again.

As a crazy modeller and wargamer with not enough time to play, I tend to direct my frustration on the later subject on crazy projects. One of my recurring ideas was to create a tank that was completely mine. I mean, completely built from scratch, without any bits from vendors, and cast it to form a massive army of custom resin models wich I could trow at the heads of my would-be opponents (I have not played a game in the last ten years, so my grasp of the rules could be vage). I finally decided to do something soviet-themed... big threads, boxy shapes... and the first model would be close to a KV-II... You can take a look at the final results and whole WIP here.

Next time, You'll follow me as I cast a copy of one piece of my master scratchbuilt.

Here I am... And in the beginning was: The Baneblade

(Versión en Español)

Well, it seems that finally I have decided to post my ramblings on behalf of the modelling community.

I will try to maintain here a log of all my work in progress and, from time to time, I hope to finish something, place it here and share points of view with you.

My main interests lay in Warhammer 40K and WWII modelling. Mainly in the scratchbuild part, making my own personalised vehicles (for the Imperial Guard, I am at hreadhead after all) as I find very difficult just to mount something just "out of the box"

This blog wil be hopefully full of tutorials and techniques someday, so if you just come here and find something that you like and you want an explanation, just write me a word and I'll do a little tutorial.

Enough spoken. I want to share with you my first piece of pure scratchbuilding. A Baneblade... Looking at this, I just think how much time I losed and how many mistakes I did two years ago...

I never finished this baby (you'll see that this is a classic on me), as it is not in my hands anymore. If the current owner sees this post someday, I'll wish him many happy victorious battles!

You can see the whole WIP here.