www.TK560.com

[TroyO]

My table is coming along, all but the oven is finished and the oven should (Hopefully) be done this weekend.

Which turns my thoughts to moldmaking, etc.

Couldn't you sculpt in clay, then put the clay master in the freezer to "firm" it up and then pull a vacuum mold with some Med weight plastic and fill that with plaster (Hyrdostone or similar) to make solid pucks for pulling duplicates?

Just a thought... the MDF masters sound great but it seems you'd have to be copying something dimensionally "known" rather than just creating something from imagination where you might want to shape and detail it as you go.

[crashmann]

Using clay for the master sounds like a great idea to me. My neighbor is a professional sculptor, and she gave me a 25 pound block to play with. It's important to keep working at the clay, spritz it with water from a spray bottle, then cover it up tight every night. You don't want it drying out prematurely.

Also, instead of making the form out of solid clay (really heavy, and takes a boatload more clay!), you might try making a rough form from the expanding foam in a can. Squirt out enough to be 70% of the final size of the piece, then layer on the clay.

My friend is using 4 pound insulation foam, and we pull .060 HIPS directly over it. Of course, we need to be gentle, since the foam is brittle, and you don't want to break the master when releasing the original sculpt. Clay should be just fine on the forming platen, even without the freezing.

Then fill the new mold with Hydrostone, sand down any rough spots (I like to use a random orbital sander) and carve out the details (everything gets softer on the table ) and voila!

(Quoting Bill Cosby) "Buck Buck number one!"

Then, when you're done with that part, you can reclaim the clay, and use it to make a different piece.

Furthermore, with the .060 pull, you've got a mold master so that when a buck deteriorates beyond repair, you just pour a new one

Let us know how it turns out!

Charlie
TI-386

[TroyO]

Hmmm, sounds like you are talking water based clay. I hadn't thought if that, I was just thinking of regular oil based clay. The way water based/pottery type clay dries hard that would make a lot of sense.

[ANH trooper]

One thing to note though,the water based clay can crack big time if it is applied too thin and allowed to dry.It must be kept moist and covered up when not in use as suggested above.

I made body castings for sculpting my armour moulds and I had quite a few crack up before I realized what to do.No fun sculpting the same part 3 times

You can coat the clay with a hardener if you want before forming over it.I reckon it should be OK as long as the clay is quite firm before forming over it.

[crashmann]

You can also use oil based clay, but believe me, you will not need to freeze it in preparation for forming! My friend is sculpting a clone trooper helmet from that stuff, and it is really difficult to work with. The clay needs to be warmed up before it becomes pliable, so I loaned him my heat gun to help with the project. Also, it is very difficult to smooth out the clay 100% Supposedly it can be thinned with lighter fluid, but that just sounds like a really bad scene waiting to happen

At this point, you can still see where the clay was carved out with the sculpting tools. So we're making a silicone mold, then casting with plaster. The plaster will be sanded glass smooth, then we'll make another silicone mold from that. This mold will be used for production.

Obviously, the benefits with the oil based clay is you don't have to worry about it drying out, but it's just really hard to work on (literally!)

You will probably lose some details when forming plastic over the clay, since the plastic is at ~300 degrees and the clay softens with heat.

Good luck!

Charlie
TC-386

[ofthesith]

I've found that putting oil based clay in a microwave softens it up alot faster than a heat gun, lol. And while it is difficult to smooth out, using a regular spoon and mineral spirits may be what you need to get that baby bottom smoothness... I've used this method on projects and it seems to work out well for me. Might cut out a step in your mold making for ya.

[jegner]

good tips. My mold making for vac-forming is MDF plywood and bondo. Since I have access to wood working tools, and have 20 years of experience dealing with the stuff, this is the medium I prefer for the vac-molds. Block up the shape, then grind the design out. If you boo-boo, bondo that puppy, sand and start over!

IMHO

Jim

[TroyO]

I just realized another method that will probably work best for me.. i do lifecasting, and as part of the supplies for that I have tons of Alginate so I can easily make a mold of a clay sculpt with that and fill it with hydrostone.

I could do the MDF route, I have most the tools... table saw, several varieties of sanders, router etc. I'll probably reserve that for stuff I plan to make a lot of, tho.

[!AliG]

I think you are right guys!
_________________
I like to like it!

[propsculptor]

Here is another option from TK560's how-to Guides,
Vacuform molds from MDF by Blaxmyth
http://www.tk560.com/blaxmyth/blaxmyth.html

Awesome series of pics, and very helpful,
Thank you both TK560 & Blaxmyth

[TK161]

One thing with alginate though it tends to shrink pretty quick.

When I smooth oil base clay I use a tool called a rake. It basically a loop tool made out of a saw blade. You rake the clay in various directions. You start with a large tooth tool and work your way down to the small tooth rake. Then you can smooth the oil clay woth a brush and rubbing alcohol. Rubbing alcohol works great with roma plasticina clay. That's what I use.

There is a really nice water base clay called WED clay. It was created by Walt Disney, hence the name WED. The automotive industry uses it and it can dry with less cracking than normal water base clay. Once it dries a bit it can be tooled to an extent. It can crack with the tooling though. It's a very nice clay for working into a smooth surface. It can be built up quickly and then let it dry for awhile and then you can carve in detail and it would hold the detail pretty well. There is some shrinkage when it dries though.

[TK161]

Also, Thurston James mentions about vacuum forming clay in his book. He vacuum forms a thin sheet of plastic over the clay first and then forms the thicker plastic over the thinner plastic.

[propsculptor]

If you are going for a machine finish I would suggets that you go with Chavant Clay, it is a clay without Sulphur in it , Rob Bottin's FX Crew sculpted Robocop out of because it can be smoothed-out and polished, they even use it for sculpting Car designs out of:



Here is their website:
http://www.chavant.com/

[thebluecanary]

I got my clay from here: http://www.artmolds.com/category78.cfm

I got 40lb of the stuff, but I only paid $100 at the time.

I can build a box in wood. I can build a deck, but sculpting in wood... Yeah... not so much.