Two Part Moulds

[Anglia105E]

Hi everybody, hope it has been a good Christmas for you all.

Sometime early in the new year I shall be using Liquid Blu-Stuff to produce moulds for casting 1:24 scale engines, and if all goes well I would like to mould and cast a complete body shell. The product used for the casts will be Black Milliput epoxy putty, and I have studied videos showing the use of a box assembled from Lego bricks. My question is what do forum members recommend to pack out the interior of the body shell for the second mould? They appear to use some sort of plasticine type material that is white or brown in the videos. I understand the process for producing the first interior part of the mould, so it's just the process for the second mould of the body shell exterior. Already practised by casting a radiator grille and a wheel and tyre assembly, but using Oyumaru instead of Liquid Blu-Stuff.

Thanks for any helpful replies., David

Edited December 27, 2016 by Anglia105E
Sorry, confused first and second part of the mould

[my66s55]

Kleenklay  http://www.sculpt.com/catalog_98/clay/kleanklay.htm

Also this video may help  https://www.youtube.com/watch?v=dBEK_Jyfvek

Edited December 27, 2016 by my66s55

[Mark]

If the black Milliput epoxy is similar to the other colors, I would have doubts about having the ability to press it into a open, one-piece silicone rubber mold without the mold itself distorting.  I can't see two-piece molds of any kind being workable with epoxy putty as the casting material.  

[Ace-Garageguy]

If the black Milliput epoxy is similar to the other colors, I would have doubts about having the ability to press it into a open, one-piece silicone rubber mold without the mold itself distorting.  I can't see two-piece molds of any kind being workable with epoxy putty as the casting material.  

Exactly. You need a pourable product.

Edited December 27, 2016 by Ace-Garageguy

[Anglia105E]

Thanks to both Mark and Ace-Garageguy, and sorry for the delay with my response. The Liquid Blu-Stuff product is poured into a 60 ml container, and around the original assembled part, in this case a straight-6 cylinder Rolls-Royce engine which is placed in the centre of the container. Once the mould is carefully cut open with a scalpel knife, and the engine part is removed the Black Milliput Two-Part Epoxy Putty would then be pressed into the mould and the blue mould would be placed back into the same container. Any excess putty should be squeezed out as the mould returns to the container in which it was formed. I am hoping this will work, so the first engine to be cast will be an experiment as it dries overnight !

[Anglia105E]

Thanks also to my66s55 and I realise now that in my original post I was asking about moulding and casting a body shell, so my point about the engine part is not quite the same issue, sorry. My thinking is that if I can successfully produce a 1:24 scale engine then I would like to use a similar technique to produce a complete body shell. It's been a busy week and my brain has turned to mush !  Sorry guys.  David

[Ace-Garageguy]

 Once the mould is carefully cut open with a scalpel knife, and the engine part is removed the Black Milliput Two-Part Epoxy Putty would then be pressed into the mould and the blue mould would be placed back into the same container. Any excess putty should be squeezed out as the mould returns to the container in which it was formed. I am hoping this will work...

Probably not. Those of us who cast things always use a pourable product...unless you do the old "slush-cast" technique, which just doesn't work very well.

You can try to reinvent the wheel if you really want to, but I'd bet money you'll be very disappointed with the results.

There's simply no way that something with the doughy viscosity of Milliput will flow into fine details, etc...unless you have rigid steel dies and inject the stuff under high pressure.

I don't know which videos you've watched, but this is one of the best series in the known universe...made by the people who make the products you need, so you don't get any fubar idiot information included...

http://www.alumilite.com/store/pg/21-How-To-Videos-Alumilite-Mold-Making-Casting-Materials.aspx

Here is another very good series. I've used these techniques and materials from both manufacturers, They work, pure and simple. No surprises, no BS.

https://www.freemansupply.com/video.htm

Edited December 30, 2016 by Ace-Garageguy

[dodgefever]

Yeah, there's no way you're going to get Milliput to work with a silicone mould,  You need a low viscosity polyurethane resin.  That Blu-Stuff looks pretty expensive too - I use EA Silicones, a 1kg kit comes in around £20.

Edited December 30, 2016 by dodgefever

[Anglia105E]

Ace-Garageguy and dodgefever, I shall certainly take your advice and I am fortunate that you have pointed out the potential failure of my plan. Thanks for the impressive selection of 'How To' videos which I intend to study closely before proceeding. The Milliput did work well in respect of the fine detail with the Oyumaru product, but the liquid resin looks like the way to go. The Blu-Stuff is pretty expensive as you say, but many of the American products mentioned on this excellent forum are not always available in the United Kingdom. or indeed Europe generally.