Only another molding question!

[Dr. Robotnik]

Hi guys,

I have been looking into making reproductions of the parts for my Hobby Products 1/8th car restoration for some time and have finally got the help of a UK RC car body manufacturer. I can get a body molded for £12 and the radio boxes for £5 if I can supply the molds myself.

My big job this weekend is to create some plaster molds of my Hobby Products Texas Wild Baja body, radio box and radio box lid. I have 3kg of Herculite No.2 which I have been advised is a good medium.

The first part I will try and mold is the radio box lid as it's about the size and shape of a tupperware container lid. Next the radio box and then finally the body.







The thing is, they have all been cut and cracked used and abused! So how can I prep. them to mold properly? I was thinking if I taped over all the cracks and filled the gaps with card to build up the sides and make it like an uncut body I'd be well on the way right?

However do I need to make a molding box to support all this in too? What do I fill it with? Sand?

I know I have rambled and asked a million questions but any help is much appreciated. I am reviewing the past threads but any further assistance or links to websites would be greatly appreciated. I only get one crack at this so I need it to go right!

Warm regards

Ed

[Erich Reichert]

I would definitely make a box and fill it with sand to support the body. I actually just got back from the molders talking to them about reproing a bunch of stuff i have and he suggests using sand for everything just to be on the safe side.

[mikedealer]

hydro stone is the way to go for molds.. strong as hell

plaster.com sells it

[Erich Reichert]

I bought some hydrostone to experiment with... got a question. How does it release from the body? Do you use anything to help matters?

[mikedealer]

i use vaseline. Not the Prison Pleasure stuff... like real vaseline in the white liquid form.

i have heard people use Meguiar's Car was also, or beeswax.

The real vaseline stuff should be available at good quality art supply places in the mold sections. It cleans off the bodies easy too so they arent ruined... wax seems messy

[Dr. Robotnik]

I am using Herculite No.2 which is pretty much the same as Hydrostone. I was told that wiping on a thin layer of WD40 acts as a release agent but on lexan or other polycarbonates that shouldn't be an issue.

[Erich Reichert]

i use vaseline. Not the Prison Pleasure stuff... like real vaseline in the white liquid form.

i have heard people use Meguiar's Car was also, or beeswax.

The real vaseline stuff should be available at good quality art supply places in the mold sections. It cleans off the bodies easy too so they arent ruined... wax seems messy

real vaseline? like the stuff in the tub... this?

[dangermouse]

I recently made a few moulds from an uncut Frewer Dog (Cat XLS replacement) body. I just used casting plaster to get the hang of making moulds.

I read somewhere you can use dishwashing liquid for mould release. I mixed some up in a spray bottle and sprayed the inside of the body before pouring the plaster. Removing the mould seemed initially difficult as the body didn't want to come off the mould. After a bit of cursing, I had a bit of a brainwave, took it up to the shed and blew some compressed air between the body and mould.... It just popped straight off.

DougM

[Dr. Robotnik]

I recently made a few moulds from an uncut Frewer Dog (Cat XLS replacement) body. I just used casting plaster to get the hang of making moulds.

I read somewhere you can use dishwashing liquid for mould release. I mixed some up in a spray bottle and sprayed the inside of the body before pouring the plaster. Removing the mould seemed initially difficult as the body didn't want to come off the mould. After a bit of cursing, I had a bit of a brainwave, took it up to the shed and blew some compressed air between the body and mould.... It just popped straight off.

DougM

Was it a struggle with or without the mould release? I don't think for the radio box lid I can get an airline or something similar in to do that...also apparently mold release agents can make the form untrue. I was going to do it this weekend but I didn't have a measuring jug and a weighing scale. I now have some and will try sometime this week...

[dangermouse]

It was hard to remove as the mould was stuck into the body due to a vacuum effect. LOL. Being such a snug fit and still being damp, it is hard for air to get between the body and mould, to allow them to separate easily.

That was using the dishwashing liquid as mould release. The plaster didn't stick to the polycarbonate at all.