Ishkur Cinderhat:
@Sharp: that’s why I’m using one-way containers and spoons for everything. It’s impossible to properly clean any stuff from the un-vulcanized silicone and you definitely don’t want to contaminate your original material with any residue on your spoons.
Use cheap stuff like empty yoghurt cups as I do, so you don’t mess up any important glasses or something similar. 
asheira:
All Hail Ishkur Cinderhat The Greatest Hobbiest This Game Has Ever Seen!!!
Thanks for posting this totorial!
Hashut’s Blessing:
I’ve just realise something, when actually casting them, do you fill both halves of the mould with the liquid and let them set, then trim and glue the two halves together or do you fill both moulds and somehow press them together whilst liquid/part-solid?
I thought the two halves might be easier and produce less air bubbles. Is it possible to drill a hole or two into the top of the mould of each model and pour it into that, so you fill the model from feet to head? (the second hole would be for air…) Cheers and thanks again!
GRNDL:
@Hashut’s Blessing
That is recommended for doing large pieces, but generally speaking with a two-piece mold you pour once and get the whole thing. If you do each side seperately, you’d do 3 pours. One for each side, then close the mold and pour the last one to bind them all together. You shouldn’t have to pull the pieces out and glue them together, unless you’re doing a multi-part figure/kit. (ie: body, head, arms/legs, weapon, all seperate)
(sorry for chiming in on Ishkur’s tut)
Hashut’s Blessing:
So, how do you actually fill both sides of the mould at the same time wholst it is closed? In the method I mentioned where there are holes drilled down to the model to fill from the top?
P.S. Thanks.
asheira:
@ HB
Usualy you’re suposed to make an opening when making the molds so your can pour the resin into it.
(my hobby book [though it’s about 20 years old] says to make it with some of the clay, or use some cylinder of some sort)
That way you don’t have to drill anything.
Ishkur Cinderhat:
This shall be answered right away, Hashut’s Blessing! 
PART II: Casting
[1] What you need: two-part resin, some clean cups to measure and mix the resin, a toothpick and the mould-release agent.
[2] Prepare the mould: I apply a thin coat of mould release agent. This is not necessary for each and every cast, but will help with the cleanup after casting, so I usually apply it after every third or so cast. 
[3] Mix the resin: I put a small quantity of resin from the original pot into a smaller cup, from where I will take the required amount with the plastic spoon and mix it in a third cup. This ensures you cannot contaminate the original pot, where a chemical reaction is highly undesirable. Stir the mixture until the two colours have mixed, by doing so try not to produce too many air bubbles.
[4] Use the spoon to fill each single piece in each mould half. Try to keep the resin where it belongs, but don’t worry too much about any spillage. This step needs to be done quickly, as the chemical reaction between the two parts of the resin starts as soon as you mix them. You usually have about 2 minutes.
[5] Use the toothpick to remove air bubbles from the resin. Poke into the deeper recesses of the mould. In my case, some air will inevitably stay inside the horns and the nose tip. By hitting these parts with the toothpick, you encourage the air to get out of there and you will soon see an air bubbles rising from these spots. In the background, you can see the resin inside the middle cup has already started to set. A rule of thumb is that the more resin you have mixed, the faster it will set. Very thin pieces or little amounts of resin will take longer to set.
[6] The resin is starting to harden now after about 2 minutes. Keep watching the resin until the colour starts to change to from clear yellow to a milky white. Now you need to act fast.
[7] Pick up the mould half with the smaller amount of resin in it carefully and quickly close the mould. Press it together, you may also use some sort of weight to make sure the mould halfes are closed as tightly as possible. The resin will now fully harden inside the mould and emit heat while doing so.
[8] After a few minutes, you can pull the mould halves apart. This should go rather easily. You will see that this method produces a lot of flash, which however can be removed quite easily by just tearing it off.
Basically you do this “open mould casting” just to have a chance to remove all the air bubbles from the piece. While a “closed mould” casting would produce practically no flash at all, I always suffered from incomplete casts where air was trapped inside the mould. A centrifuge or vacuum casting method may solve this problem, but until then I find the open mould casting and pressing method to suffice for me.
[9] The final result. Your mould, clean and undamaged, the cast pieces, some removed flash. Shown here is the first casting attempt with the new mould. Once you have cast your first few pieces, you can estimate the required resin amount more precisely and won’t end up with as much hardened resin in your cup as I did here. Eventually you will have about 80-90% good and useable casts with this method.
Hope this was useful. If there are any questions I’ll be happy to answer them. Feel also free to pass your own ideas of how to improve this process! :hat off
Hashut’s Blessing:
Cheers! I shall read it after posting this and then edit my reply. Thanks for the help asheira and thanks for the quick tutorial reply, Ishkur.
EDIT: Excellent. So, had you tried the two hole closed method that I suggested, Ishkur? I thought it may help to reduce air bubbles, except possibly at the top because of the extra hole. So, air bubbles are difficult to avoid on little points? How runny is the resin when you are putting the two moulds together?
Sorry for all of the questions, I’ve just never been shown this and so never thought to ask them before.
torn:
i find resin is quite runny, probably about he same consistency a cough medicine.
i might try this method, although it looks a little messy. what i have been doing is implanting a cone into the mold while it is setting and pour into that with both halves together. i do get a lot of air bubbles but im going to try one tommorow with extra air escape tunnels, as i didnt really think about that first time. If it doesnt work ill have to try your method.
once again a great guide! its no wonder you won that trophy 
Hashut’s Blessing:
torn: that method is what I was suggesting (with the air escape tunnels). Let me know how it goes, please.
Is it possible to let the resin thicken a little more before placing them together? That could reduce flash and possibly air bubbles (air getting in during the rapid movement?)…
GRNDL:
Interesting. Thats not the way I do it at all, but obviously it works.
I add vents and pour holes to my molds, so that they come together and you just need one pour and know where the resin is going to run out. The pour hole is a wide cone at the top. As you pour the resin in, air is slowly forced out of the vents as it fills the mold up. It works pretty well, but if you have “long, spikey” bits pointing toward the outside of the molds, you will get lots of air.
Ishkur’s method definitely allows you to see where the air is trapped and gives you a chance to get rid of it. In order to do this my way, I’d have to do what I described as the “3 pour” way.
Ishkur Cinderhat:
Is it possible to let the resin thicken a little more before placing them together? That could reduce flash and possibly air bubbles (air getting in during the rapid movement?)...That's what's happening when the resin starts to set. I wait for the first milky spots to appear, as then the resin starts to harden and won't spill everywhere during the closing but pretty much stay in place.
Hashut's Blessing
Xander:
A very interesting method, for sure! I had only read about the air venting method. Hehe.
I am eager to try this now. Hehe.
Hashut’s Blessing:
I thought that may be the case. Is it possible to leave it a little longer so that it’s even less runny, or would they not bind together as well?
GRNDL, that’s the method I was talking of.
torn:
A very interesting method, for sure! I had only read about the air venting method. Hehe.that is a lot of HeHe's. it sounds like Xander has already locked himself in a small badly ventilated room with mixed resin whilst reading this . . . . and coming up with a dangerously fume inspired master plan?
I am eager to try this now. Hehe.
Xander
Hashut’s Blessing:
It’s the sheer amount of posting he’s trying to keep up with as well I asked if it’s easier that way and got a reply and if I could be bothered to scroll up, I’m sure I;d find it, but it should be in the thread somewhere 
Kera foehunter:
thanks again this is going to be great when i turn to the resin molding your figures rock !!!
Ishkur Cinderhat:
with that 2 half method is it not easier just to let both halves set and then glue them together?Oh, don't forget that the mould line is not straight, if you leave it in halves like that and then glue the two pieces together they will not fit or parts will be missing.
torn
GRNDL:
I think its important to tell people how resin “sets”.
When you first mix the two parts together, it goes very runny - like hot [/align]honey. Its thick but still very watery. At this stage, it will begin a chemical reaction. Depending on the resin and the proportions you’ve mixed it in, you have about 1-2 mins before it “blooms”.
As soon as it blooms, the stuff has to be in the mold or you’re in trouble. It will become very hard, very quickly and also generate a lot of heat. (If you get it stuck to your hands, you will be very hard pressed to get it off you.)
The idea is to get the resin in the molds you want and degassed before it blooms. After it blooms you just need to wait 10 mins or so before taking it out of the mold. You can accelerate this by slapping it the molds in the fridge.
I’ve also heard that some people powder their molds with talcum powder. Doing this draws the resin into sharp cracks by means of capillary action. I don’t have any experience with this though, at least, not a scientically “provable” way of see if it works.
torn:
i have come accross adding powder, apparently putting it into the mix makes the finished piece harder, but ive yet to try it.
the resin i use isnt the 2 equal parts type, but 1 part and a hardener, and has a longer play time of about half an hour before it loses its fluidity.