Sculpting/ Molding/ Casting Tutorial Thread

[dinonikes]

Here is a plaster mold- it is for casting a scale modle of a Metoposaur. It is a two piece mold- the top of the head is cast in a separate mold which is also a two piece mold. THe casting is made in a liquid latex. The latex is poured in through the hole in the top half. I will also be giving a tutorial in then ear future on this method of casting, which is one of my favorites- a much more economical material than either casting in resin or urethane, and much less work too as you basically just fill up the mold ad walk away from it, and let is sit then pour it out after proper time has passed. This is a real old mold- from the 70's. i have sold many of these models- one of my more popular pieces. You can see the finished piece on my Classified 'Prehistoric Models' thread. Rush Studios made a full size model of this critter using this scale model.

[dinonikes]

So I ended up having to do the unerside piece of the mold before the second main side of the mold as I decided it would be too hard to get the release agent down into between everything if the two side pieces were surrounding this underneath area- confused yet? Anyways- I had to set up a wall around this underside area to make a containing wall to pour into-







Then I just fill up this cavity with silicone. I use vaseline as a aprting agent on the existing silicone of the first piece of the mold- this vaseline makes the two pieces come apart when I am ready to take apart the mold when it is done.Silicone will stick to itself otherwise, without the release agent I would end up with a block of silicone with my sculpture trapped inside. There are commercial release agents available, which are aerosol sprays- but i find that the vaseline is much cheaper and just as viable as a release agent- plus it is much more convenient to acquire- any drugstore has it- so ok, I pour the silicone-



Once the silicone sets up- I remove the clay walls from the mold- this is what the two pieces of the mold end up looking like once the clay is removed-







So then i had to first clean up the sculpt- fixing any damage done to it by the last step in the mold making- then I set up clay walls again to pour the last side of the mold- unfortunately I don't have any more photos to show this step. It is basically the same as the first side i poured. I set up the walls to follow the lead edge of the silicone where it meets the fiberglass casing- right along this line. I put the vaseline on all of the silicone of the existing parts of the mold that will come into contact with this third part. I fill up the form with silicone. Once this is set up I clean away all of the clay again and vaseline the fiberglass casing and make the second half of the case in resin backed up with fiberglass- just the way i showed in the previous step shown in a prior posting. Once the mold is completed I pull apart the mold and remove the clay pattern. I clean up the mold cavity with acetone to remove all clay residue and my mold is ready to cast- voila! Fin.

[Dinotoyforum]

I see, very cool. So the middle part of the mold covers the ventral surface and the inside of both legs and arms. I guess the outside part of the right leg required the most fixing up?

[dinonikes]

Yeah, that and the mouth- the mouth needed the most attention- gettting out all of the clay that split the mouth down the middle inside was a bear to get out- no one has seen it yet but I sculpted a pretty deep cavity down to the back of the throat,plus a pretty nice roof of the mouth too- and i had a little leak back there of silicone that had to be removed- real surgery-lol. I fixed it up nicely and the cast looks pretty darn nice inside the mouth, real deep back of the throat-

[dlindeman]

great tutorial ...I will review the casting part ..that where ive always had problems

I had made a video one up here is the link to the 1st episode .
www.youtube.com/watch?v=7sWgGvKaL6g
Best
DL

[dinonikes]

Here is how I set up the parting line for the Muraenosaurus- it will be a two piece mold so I just run the parting line down the approx. middle point between the top and bottom as this will interfer the least withthe details of the sculpt- I run the line along the bottom of the lower jaw so as not to cross through the details of the face, especially the mouth area-





I set up the retaining walls with stiff cardboard, that is hot glued at the bottom and any connecting points between the pieces of cardboard that make up the wall- then it is ready to fill up with the silicone-

[dinonikes]

I made the Para mold in two halves- you can see in these photos how the parting line was set up to create this two piece mold-

[Seijun]

What's next??

[dinonikes]

The process forthe Para mold or the Muraenosaurus is the same as i already show for the T-Rex- the silicone is poured and then the whole thing gets flipped over to make the pther side- I just posted these as alternative ways to set up the parting line- to show how each figure is different in the way the seam or parting line is set up- but once the parting line is set up the process is pretty much the same as i showed completely with the T-Rex- i didn't want to tie up[ the thread with repetitive info- when I make a different style mold i would post photos of that process completely-

[Seijun]

I thought you might show how you go about pouring a casting with it.

[therizinosaurus]

Are all of your molds 2 parts, or are there any that will require more?

[dinonikes]

I had planned on showing the casting process- it is basically mixing the two parts of liquid urethane materials together (there is the base urethane Part A, and the hardener Part B)then pouring it into the mold once the mold is assembled(pouring as slowly as the QUICK set up time of the material allows, so as to not create bubbles in the cast- you wantto let the material fill the mold up slowly, rising and pushing out any air ahead of the material towards the opening that you are pouring into)- wasn't sure how to photograph that to really show it, plus the material sets up in a few minutes so there is a real time crunch involved- will have to get my wife to take photos of the process as i do it-

The Rex mold is actually a three piece mold- I try to make two piece molds when I can, but sometimes the sculpt is too complicated and needs the extra piece or possibly more-

[EmperorDinobot]

Sweet process. Thanks for sharing!

[dinonikes]

This mold was a pain to set up- the piece was big- 23 inches long approx.- the wide position ofthe fins made it stick up a lot off the base board- so i had to construct quite a support system under the parting line shelf to hold up the weight ofthe clay used to make the parting line- I usually use blocks to build up and shore these mold shelves- but in this case I just used up the pile of clay I had on hand to make the supports- this goes pretty quick once you figure out how you are going to go about it-

[Gorgonopsid]

Hope its ok to post this here.

I made a Meganeura out of playdoh type clay. Just haven't taken a pic of it yet.

Its just sitting on my computer desk.

[camara]

You should use sculpey or Chavant.I see that you have some problems with the sculpt while molding,and it suffers a lot.Sculpey is GREAT for details,equal as Chavant or Roma.Try Super Sculpey Firm mixed with fimo!

[Gorgonopsid]

Jan 31, 2009 15:56:29 GMT dinonikes said:

Here is a plaster mold- it is for casting a scale modle of a Metoposaur. It is a two piece mold- the top of the head is cast in a separate mold which is also a two piece mold. THe casting is made in a liquid latex. The latex is poured in through the hole in the top half. I will also be giving a tutorial in then ear future on this method of casting, which is one of my favorites- a much more economical material than either casting in resin or urethane, and much less work too as you basically just fill up the mold ad walk away from it, and let is sit then pour it out after proper time has passed. This is a real old mold- from the 70's. i have sold many of these models- one of my more popular pieces. You can see the finished piece on my Classified 'Prehistoric Models' thread. Rush Studios made a full size model of this critter using this scale model.

Do you have the finished product of the first mold?

[stormnl]

wow,,i like that mammoth,,great work

[[][][]cordylus[][][]]

Orthocone, it's a metoposaur, and it's $50

[stormnl]

Orthocone,,,were can i found ,,more of that mammoth?