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reevz666 Profile
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Caped Crusader

Registered: 05-2004
Location: San Diego
Posts: 2689
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Plaster Mold of a Urethane Hardcopy


okay, I'm going to make a plaster mold with my collapseable Urethane foam filled cowl. I wanted to know if I needed to spray anything on the urethane to help it release from the plaster mold ? and do I powder the mold before pouring the....

Latex!..I was going to go thought FX warehouse( are they any good?)...and I have heard many ways to color mask latex( acrylic paint, ink,ect)...does anyone have any experience with this or a better solution?...

thanks guys!

Last edited by Deadly Lemur, 3/20/2006, 11:52 pm


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10/12/2005, 7:43 pm Link to this post Send Email to reevz666   Send PM to reevz666
 
cursedbat Profile
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Apprentice

Registered: 02-2004
Posts: 297
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Re: Latex and Urethane questions?


I've never used any release with stone to urethane. If you do it can make it even harder to get the stone to lay on the piece.

The bigger challenge might be doing the stone mold if you dont have allot of experience with it. Especially on a flexible piece it can be a pain. I know I've broken many things from getting frustrated with stone in the past.

Fx warehouse is good. Thea will treat you right.

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Dont disrespect the archetype with the pathetic sides of the human condition


10/12/2005, 8:32 pm Link to this post Send Email to cursedbat   Send PM to cursedbat
 
reevz666 Profile
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Caped Crusader

Registered: 05-2004
Location: San Diego
Posts: 2689
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Re: Latex and Urethane questions?


instead of stone, could I use fiberglass instead??

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10/12/2005, 8:39 pm Link to this post Send Email to reevz666   Send PM to reevz666
 
JBrown437 Profile
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Caped Crusader

Registered: 08-2004
Posts: 2122
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Re: Latex and Urethane questions?


This is what I did...

First I sprayed the whole urethane foam filled bust down with Epoxy Parafilm release.

I used Ultra Cal 30. It's not expensive at all, compared to silicone at least. First, I poured a little water into a bucket and scooped up a cup of plaster and sifted it into the water. Using an electric beater, I stirred the mixture. You need considerably more plaster than water, so keep that in mind while mixing. I added plaster and water as necessary until getting an “icing” like thickness. From here, I brushed it all over my foam filled urethane cowl, covering the whole thing in a fairly thin layer of plaster getting into all the crevasses. Once that was done I let it dry for about 30 min and then repeated the process 2 more times. Then, I cut up lots of 2” srips of burlap. Then, I mixed up a little bit thicker batch of ultra cal and dipped the burlap, one strip at a time into the plaster getting it completely covered. Then I covered the entire thing with the plaster coated burlap, smoothing each strip out to make sure the were no air bubbles trapped under the strips. I let that dry about 30 min and repeated the process another 2 times. Then, I mixed up an even thicker batch of plaster and completely covered the entire thing in very thick plaster. I completely filled in the gap between the ears and flattened the top so it could stand on its head later. By the time your done, you should barely be able to tell where the nose chin and eyebrows were, but the ears will be completely buried. Then, smoothed the whole thing over with water and I was done. I let it dry overnight.

The next morning, I pulled the urethane foam filled cowl out of the plaster mold. To do this, first, I reached my hands down the sides of the mold between the urethane cowl and the plaster and separated the two. Then, I had to scrunch it up real good to get it out. All in all the plaster mold came out beautifully and I just took 220 grit sandpaper to the inside smoothing out the rough spots and filling any holes with the bondo glazing and spot putty and sanding it down once that dried. The smoother the plaster mold, the smoother your cowl will be.

Hope that helps.
10/12/2005, 8:59 pm Link to this post Send Email to JBrown437   Send PM to JBrown437
 
reevz666 Profile
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Caped Crusader

Registered: 05-2004
Location: San Diego
Posts: 2689
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Re: Latex and Urethane questions?


thanks for the advice!...where did you get the Epoxy Parafilm release??

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10/12/2005, 9:03 pm Link to this post Send Email to reevz666   Send PM to reevz666
 
cursedbat Profile
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Apprentice

Registered: 02-2004
Posts: 297
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Re: Latex and Urethane questions?


The way to apply stone is to do it all at once. If you dont you get a mold that will be slightly weaker and will wear down faster if you want many flawless pulls. Also stone is pourous so you can run into problems with using non pourous materials to do patch work. You can get parts that dry uneven. It can though be done but...And again you dont need a release for stone to urethane it can contaminate the mold and makes it a pain.

Yes its much easier to put on polyester resin but will present some new challenges. Order yourself a can of polyester parafilm, you can do a google search should be about $12. A thin coat for a release on the urethane is all you need. Lay down a gel coat and than a reinforced coat with resin and fiber strands.

When I first started doing the application of the latex it was a bit different from that of slushing into stone in that I wanted to slush in the second and third layers instead of hand painting every layer. But if I didn't get a good base layer down often the tiniest of bubbles would show a little. Sometimes even a bubble just below the surface would get heated up by the sun and the air would expand making it show on the outside until it cooled off.
You just need to work out a system to get the material on the inside of the fiberglass easy, bubble free, and do a quick build up. Use a fan and some good sunlight to dry in between coats.

You can use molding latex but it isn't necessary. FXwarehouse has some god RD latex.

Good Luck!



Last edited by cursedbat, 10/12/2005, 9:21 pm


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Dont disrespect the archetype with the pathetic sides of the human condition


10/12/2005, 9:13 pm Link to this post Send Email to cursedbat   Send PM to cursedbat
 


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