Moldmaking Moldmaking Links & Tips

Great Thread! I posted this before but I'll post it again to keep everything organized and since I love it.

Hellboy Bust and Matrix Mold Making Tutorial: Two part mold done by making a hard, outer shell first than pouring the silicone in the shell around the part.

To help with bubbles if you don't have a pressure pot or vacuum chamber, you can "paint" a thin layer of silicone over the model first than pour over that (right after the thin layer, before it starts to cure).

To make tiny air vents (so it doesn't take much cleaning up) I used plastic coffee stirrers (from McDonald's :p) and I just used a tiny bit of hot glue to hold it in place (it wasn't very sturdy but enough to stay put as the silicone cured). It worked well; I just had to make sure there wasn't any resin in the holes the next time I cast.

Make sure to make a large enough pour spout! You can get away with making it thin, just if you do make sure it is long enough. You want to have enough volume to overfill the mold because if it is perfectly level with the top, if the resin settles or leaks a tiny bit, it will cause a gap if there is no more resin to fill it.

Plastic syringes, like this are super useful for filling small molds with a thin pour spout. They are also useful for measuring small amounts of material. You can't get much use out of them though since the resin will wear away the lines and it is difficult to prevent it from getting clogged.

I am sure I will think of more stuff later. I am going to try to make a glove mold next week so it that is a success I am sure I will have info to share on that. Also, I could be wrong, but I doubt the Silputty would hold up to casting resin. The tear strength also sucks. It would be good for wax or pushing clay into though.

 

Re: syringes and marks on measuring cups... they do wear away, but what can help is putting some clear packing tape over the top to protect the lines.

 

Thanks for the tutorials! The Hellboy tutorial has a way of mould making I would have never thought about before. Casting still looks really scary to me. o_o

If you ever do make those chocolate dollies, post them, Morgan!

 

Here is my tutorial I am making for a glove mold.

Here it is:
Glove Mold Tutorial

I should be done it next week.

 

I thought I'd share this tutorial from the Concept Art Forum, Its a tutorial for making a two-part Matrix Mold which is one of my personal fave techniques, its done with a Hellboy Bust but the same technique is easily applied to doll casting.... Whilst its very time consuming its also great for really sturdy long-lasting molds that are super strong and use a LOT less silicone... I used this type of mold for my Mermaid Tail...

Hellboy Bust and Matrix Mold on Concept Art by Ivar L

 

firefly, that's the best mother mold ever!! :XD

 

Here is a great source of moldmaking knowledge and products....

http://www.smooth-on.com/index.html

 

any ideas on how to cast something with a hollow centre? ^^; are there any links? if i like the first doll i make, i'd make a cast of her so i can remake her a good few times

 

http://www.bjdartists.com/joints/showthread.php?t=1406&highlight=hollow

 

Just another link with threee video tutorials. This guy does not cast figures, or dolls, instead he casts little axes for (probably) warhammer-type figurines. He is, however, very thorough explaining all the bits and pieces that come with pressure casting and I've learned a lot just watching how he works.

http://www.the-warforge.com/pressurecasting

 

hello ,
i think im very confuse... i dont know how im going to make my doll's head hollow on mold, my prototype have hollow head , i read a lot of thinks about molding the face but i can find any tutorial of how i leave the head's inside hollow. please healp !!!!

 

If you have a DoA account you can view these threads, the tutorials are very simple, but explain the process in text and images: http://www.denofangels.com/forums/showthread.php?45964-How-Do-You-Cast-A-Hollow-Head (by Kaye)
http://www.denofangels.com/forums/showthread.php?61538-first-try-at-resin-head-merlady-added-too (by Patl)

 

thanks twigling , i have a account on DoA , im going to see the tutorial !!!!

 

Are resin torsos cast hollow?
If so, how is the core removed after casting?
Is the torso cast in two pieces and epoxied together afterwards?

In all the pix I've seen so far, it looks like the torso is cast in one piece.
That seems like it would use too much resin, and be too heavy?
Especially for the larger dolls.
Even if the torso has two pieces, the lower torso really doesn't have
a hole for removing a core, that I can see.

I do not own an ABJD, so I don't know about the ones made in Asia.
KW

 

A one-piece torso cannot be cast hollow, it would need to either be drilled or have rods placed where the holes will be. The rods are pulled out when the resin is hard. I suppose a one-piece torso could also be hollow if it were slush-cast.

Two and three part torsoes are cast with an internal core but is cast in one piece. The core-mold is simply pulled out like a plug from a socket, but the shape of the hole must be considered, you cannot remove a 5 inch sphere through a 1 inch opening. Whatever hole is made in the torso it must be wider at the top than at the bottom, so that the silicone coremold plug can physically be removed.

The outer and inner mold must somehow interlock beyond the cavity where the resin is poured.

The top of the lower torso is usually the larger opening where the coremold is pulled out, some dolls have a separate resin piece that is glued into that larger hole after demolding, to make the hole smaller ~ this limits range of motion which is sometimes good and sometimes you wonder why they did it.

I see that I didn't show specifically the inside of the lower torso or the lower torso core mold in my tutorial threads, but you can see here (sort of) that the lower torso has a hole in the top, this hole is about 1 inch by 2 inches and extends deep into the torso and exits through the hip sockets, without really changing shape or bulging out. When molding, the hips are filled with clay so the silicone cannot escape. When molding the outside mold part, the walls are built beyond the top of the torso, and so the silicone also will rise higher than the torso. After the first part is cured, the second part can be poured and will fit like a plug into the top of the outer mold and also into the inside of the lower torso. The plug pulls straight out after casting, because it is straight.

It can be very hard to wrap your head around this without seeing a doll and being able to pull at it to look inside the joints and stuff.

 

Silicone Rubber molds made easy

OK Im tired of you guys trying to kill your selves lol.The easyist rubber to use is made by
Alumilite.The hs3 is the best for making doll molds.
1. make your mold box out of foam board 3/8 "is best,seal edge with hot glue.
2.mix a small amount of the rubber
3. paint your piece
4. let it set for an hour
5. mix the amount you need for the entire mold
6 pour your mold and let rest for 24 hours
7 cut a small slit to remove piece, the is the most elastic of all silicones
8pour a small amount of alcohol in the mold and twist it to relieve the suction
9 remove piece
10.let dry and your gtg
Note this is a 10to1 silicone,
Please get a dig. scale as it is important that it be 10/1
This silicone has 2 parts one is white and one is pink ,your mold should look like bubble gum
Also due to the dye in the catalyst pore you new mold for a waste as the first resin may have some pink dye.
NO VAC OR POTS JUST YOU AND YOUR RUBBER . HAVE FUN

 

Have you worked with that new mystery-magical resin yourself? If so can you give any hints about what it was like to work with, what sort of viscosity, potlife, curing time, mixed and cured colour etc it has. Is it opaque or transparent?

The method you describe for the silicone is interesting, but as I prefer to pot my resin, I also need to pot my molds first, otherwise there will be undesirable instances of the 'porcupine effect' when I pot the mixed/poured resin. I have also used materials with similar properties as the HS3, and I agree that the soft-soft silicone is great for some applications like one-piece and glove molds wherein you get a minimum of seams to have to clean up. However HS3 is a tin cured silicone which means it has higher shrinkage and lower durability than platinum cured silicone. Tin cured silicone is okay but some resins cannot be poured in it without negative consequences.

 

i prefer the 50/50 rtv silicon as even measuring carefully the 10/1 just didn't work.
plus i don't have to pay any extra as it's in the uk already, doesn't need a pressure pot and i only ever had about 2 bubbles in 3 molds with hand mixing.

 

Well you asked for an easy product to use and i gave you one lol.But you should use what you know best i just hate seam lines.this product works very well for doll molds i have used it alot in the past.fyi if you dont know who i am, google me ,i have been on every cover of every doll mag there is lol and sold over 500,000 dolls in my life time. and yes you can go see it on my web site that will open monday or tuesday cindykochdolls .com have fun tig

 

You might be able to create a hollow, one piece torso with a wax core. It could be held in place in the mold at the holes in the neck and where the legs would go. The wax could be melted out after the resin cures. Obviously, you would have to make a new core for every piece. I don't know if the heat from the resin would mess up the wax though, or how melting the wax would affect the resin. Just a thought.

 

hello, and kisses from the hot Thessaloniki the tempature today is almost 40c and i went for some shoping for mymold , ok i buy plastelin but i could not find any material for the mold box and im so confused... ok my for head im going to use a plastic cup but for the other parts? i saw the legos in some tutorials but it was very expencenve what else can i use for mold box? if i use very strong paper you think it will be ok?
thanks
gerakina

 

Mold box

You can use whatever material you can seal for a mold box, basically.
The Legos are a bit expensive initially but where they save you money is twofold:
1. They are reusable
2. You can EASILY make complex boxes to fit your piece so you save money with mold rubber usage....In the long run saving money on the mold rubber is what counts IMHO.

 

thanks jco415 for the quick response to my message, i going to think all about legos
thanks
gerakina

 

Hello Gerakina.

Legos make quite an expensive mold box.

Cindy Koch recommends using foam board, with the edges sealed with hot glue.

Twigling made very functional mold boxes from PVC pipe.

The most important things to consider when making a mold box are:
1. Will the mold box material react with your molding rubber?
2. Will the mold box material be strong enough to contain the liquid mold rubber?
3. Can the mold box material be sealed against leaks?

Why buy an expensive mold box when an inexpensive one will work?
I have used both plaster and wood as mother molds to pour silicon rubber into. A mother mold is another term for a mold box. Using plaster as a mother mold, I was able to save silicon rubber, because I could form the plaster very close to the part I was molding. With the wood mold box, I was able to place blocks of wood in areas to reduce the amount of silicon rubber used.

It is a difficult question to answer because you live in Greece, and I don't know what kinds of materials are readily available where you live.

Hopefully Helpful.

 

I also use corrugated plastic for some of my mold boxes, and use plasticine to seal all the edges. I prefer clay to hotglue because clay can be reused over and over again. I also slick it down with vaseline. I don't get many leaks. The corrugated plastic I use came from the for sale sign of our house when we bought it. I think the estate agent was meant to come and pick them up, but I figured it would came in handy and tucked them away. You could even use cardboard as long as it has a glossy (non-absorbent) surface... even regular corrugated cardboard can be used in a pinch. Sometimes also have used small plastic buckets and tubs/containers; the round ones, not the square or rectangular ones. Just make sure you have a nice smooth and rigid baseboard, such as a piece of plexiglass or laminated woodchip.

 

KW&twigling thanks for your help!!! that was real helpfull to me , and i get the point ... i can use almost everything that is strong to hold silicon inside and do not react with the silicon i think i have many products in my home that ca do that!!!! thanks you again you give many many ideas!!!! im going to post my photos soon!!!!

 

hello once again for today, i start bulding my plastelin base and i post the photos http://www.bjdartists.com/joints/showthread.php?t=3259&page=4
can you please tell me if every think its ok so far?
thanks
gerakina

 

If this is your very first attempt at making multiple piece silicon rubber molds, the best advice I can give to you is: do not rush. ( Δεν βιασύνη ).

Suggestions:
First, make sure you know all the steps to making a flexible rubber mold.
Read all the instructions that apply to the mold rubber you are using.
Make a checklist of all the steps of making the rubber molds.
As you make the molds, check each step on your checklist.
Don't forget pouring sprues and air vents!

 

hi KW thanks for the quick responce, i read all the articles and the post here and to DoA for mold making and in theory i know all the steps, but only in theory, is my very first time that i make a mold , i make the check list( i read that in a previous post of you!), i send the photos, so if someone saw a mistake to mold to correct me, it will be very heplfull to me.
thanks again
gerakina

 

Keep sending the photos as you progress in your flexible rubber mold making adventure! Many eyes can see more than two eyes. I think you are off to a good start! You are familiar with the mold making process. You have made a checklist. You are sending photos and asking others to look at what you are doing. You are not in a rush. Keep up the good work!

 

PolyTek Mold Making & Casting Manual & Catalog

PolyTek Mold Making & Casting Manual & Catalog.

This is a 68 page mold making & casting manual and catalog in PDF file format. You need a PDF reader to view this file. The PDF file size is 2661586 bytes (2.5MB).

 

thanks Kw !!!!

 

hello , im going to poore silicon this days so i have a question : should i use vazelin or talk powder for the first half of the molds ? or only on the second, when the one side is silicon and not plastelin?

 

Please read the instructions for the silicon rubber you are using.

Generally speaking, silicon rubber does not stick to most materials, however, it does stick to itself. If the plastiline contains sulphur, and the silicon rubber you are using reacts with sulphur, then you need to seal the plastiline with an appropriate separator before pouring the rubber.

When in doubt, only mix enough silicon rubber to pour one mold, let it set, and see if it works. This is good advice that I have seen on more than one molding tutorial. If something goes wrong, you only have to redo one mold, not all of them.

 

Use spray-on mold release on your master model, brush off excess with a soft brush. Wait till it is dry and mist on a little bit more. Use vaseline only in an emergency if you have nothing else, vaseline is more likely to make a mess and flaws in your mold surface because the silicone will conform to any dips and bumps formed my vaseline, rather than flattening the vaseline to the master.

Use spray-on mold release or vaseline on the silicone between the first and second pour, because silicone sticks to itself. Using mold release on your master and on the inside walls of your mold box/mother mold means the silicone will release more easily from those items.

Talcum powder or corn starch is only for sprinkling inside a complete and cured mold, tapped and round and the excess shaken (or blasted with compressed air) out. This is to aid the resin in releasing from the mold, to help prevent the formation of surface bubbles and to protect the mold (to a degree) from the heat and chemicals of the curing resin.

 

thanks KW&twigling

 

hello, i have a question , how im going to clean the first part of the mold with the prototype from plasteline?

 

Gerakina, do you mean the klean klay that holds the piece up? I use rubbing alcohol.

 

yes but i didnt know how to writed, thanks Renzi !!!

 

Sometimes I use a wooden or metal or plastic spatula to scrape out the clay, maybe a spoon (for inside the head etc), otherwise sometimes wipe with rough papertowel. But it depends a little on the type of clay, I usually just use plasticine.

 

This is an awesome series of videos, silk! Thank you very much!

 

What silicone will be the best for smooth cast 305 or 320?

 

oh boy I have just found an amazing site with tips on resin casting - this post in particular is great

http://www.resinaddict.com/forum/viewtopic.php?f=3&t=80

 

This quote, early in the post, is worth repeating:

The first and most critical thing to remember as you start venturing into the world of casting is that a lot of mistakes will be made. Accept that you'll screw up and that the early projects may not come out well. Successful casting means constantly experimenting and refining your work, so don't get frustrated if the first attempts fail. Figure out what did work correctly and figure out ways to correct the things that didn't work.​

 

ha ha yes indeed, but the idea about vent from the top and filling from the bottom is fantastic also using talc I cant wait to try it

 

That's one of the clearest explanations I've seen! Makes me think I could actually do this!

Thanks for sharing the link-- did he ever do a part 2?

 

No he replied to my post thanking him for the first post and said that he had intended to but had not yet

 

Smooth-On Cast 305 resin has been recommended for beginners, in other posts. :confused:

 

This is brilliant!!! Not doll related but brilliant:

http://www.tapplastics.com/info/video.php

The two-part tutorial is great - especially the section about using RICE to determine what volume of silicone you need.... very cool