Making a master for casting

I haven't done any recasting myself, but i stumbled on this website on how to make a mold... this might help.

http://www.microer.com/molding.htm

QUOTE: Originally posted by berny13 I picked up some Sculpey today. I'll have to make it in several sections though. Once one part is baked, can other items be added to it and rebaked?

It think it can be, never tried it myself. I tend to use sculpey rarely due to the cost and the need to watch it like hell while baking.

I normally tend to first make a core and than overlay that with the sculpting medium, reduces the cost.

I like to make most of my masters from solid styrene.

I picked up some Sculpey today. I'll have to make it in several sections though. Once one part is baked, can other items be added to it and rebaked?

Ok, here is my opinion it really depends on the detail level and size of the part that you are after.

Personally, I prefer a selection of materials:
1.) Waterbased clay for large parts that hold little detail(figs, etc)
2.) Balsafoam sealed with resin for parts with good detail in larger scales.
3.) Super Sculpey for smaller to medium scales (pricey but works well), needs to be baked in order to harden. Fimo clay is a good alternative.
4.) 2-part epoxy putty or similar for small=teenie parts that need to hold good detail, create a rough shape and than remove as needed.

Wire-Loops/Dental tools are a good addition to your tool-chest for any type of sculpting( you can make your own too).

HTH.

P.S.: Make your master about 10~12% bigger than needed and emphasize the details.
Won't really matter if you after only one pull of the mold, but casts of any master tend to be smaller and with poorer detail than the master.

I haven't made resin copies of it yet, but I have made a master of the Star Safire FLIR ball used on Marine hueys out of sculpey modelling clay. Mold the soft clay as close as you can to the contours of your part, but leave some extra material on there for sanding and scribing. Bake it in the oven, and the piece is now hard enough to sand down and scribe in the lines. A small pack is about 98 cents at any craft store.