Casting/Silicone question for the silicone guys (non pen related)

[capcrnch]

I'm thinking this is the best forum for this..

I have 2 cement VW Beetles that are garden ornaments.. They're about 10 years old and the cement has taken a bit of a beating over the years.
I got these from a guy that was making them as a hobby, but died years ago.

I'd like to make new ones, but I don't know how he was doing it.

There is some nice detail to these, ie the wheels, doors, etc etc

I was thinking that I could make a wooden box (about 1-2 inches bigger than the Beetle) fill a good portion with silicone mold, spray the beetle with some non-stick, stuff the beetle into the box, continue to fill with silicone for the sides and pray that the form takes to all the detail.

Does anyone have any thoughts? Am I thinking correctly?
I can take pics of the cars if it makes life easier.

TIA for ideas/tips!

 

[Glass Scratcher]

How big is the Beetle? Many concrete lawn ornament companies use a latex mold with a fiberglass mother mold to support it.

 

[capcrnch]

How big is the Beetle? Many concrete lawn ornament companies use a latex mold with a fiberglass mother mold to support it.

Maybe 12" long at best, 6" wide, 6" high?

I'll take a picture of it (them) when I run outside later.

 

[PTownSubbie]

You will get excellent detail. Maybe too good if it has voids or any areas in which the silicone will make a connection through causing difficulty in removing the mold from around the beetles.

What are you planning to cast it in? If you plan to make a mold, I would recommend doing some research and checking with a supplier to make sure the silicone you get has some pretty high strechability and tear strength. I would think you will have to stretch that silicone quite a bit to remove the casting....

 

[capcrnch]

You will get excellent detail. Maybe too good if it has voids or any areas in which the silicone will make a connection through causing difficulty in removing the mold from around the beetles.

That's good to hear. I planned on filling the small voids to get a clean production mold.

What are you planning to cast it in? If you plan to make a mold, I would recommend doing some research and checking with a supplier to make sure the silicone you get has some pretty high strechability and tear strength. I would think you will have to stretch that silicone quite a bit to remove the casting....

Wow, good points. I originally intended on going with cement again, but I hadn't thought of the "stretchability" factor.

 

[Glass Scratcher]

Of the reasons for using latex is the stretch factor. You peal it off like a, well- condom. Another reason for using latex it is relatively inexpensive. You have to lay-up a mother mold over it but the detail is equal to silicone. The latex mold can be used dozens of times before you need to pull your master and make a new mold.

This preview/sales video gives an overview of how to make molds for 3-d concrete casting.
http://www.youtube.com/watch?v=ZxgMnzVdMQ4&feature=related

 

[capcrnch]

Thanks for all the tips!
That video was a good hint at what im looking for!

Here's the pics of the 2 Beetles..

 

[DurocShark]

Those are cool! I want the classic beetle one!

 

[sbell111]

I'd use latex to make the mold. I'd likely use spray foam for the mother mold as it would give the latex mold enough support but still be quick, easy, and inexpensive to make. When I have cast things like this, I have used Quikrete Vinyl Concrete Patcher instead of regular cement. It handles temperature changes better and appears to whether better, also.