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I've been using smooth-on silicone to make molds for casting hard to find small parts... 

does anyone do casting and what do you use...thanks

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Posted (edited)

what silicone do you use from these companies that are best for parts...

the other thing is that I use 1:1 silicone,it's much easier for me...

Edited by retroguy

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Micro-Mark sells 50:50 two part mold making RTV.  it is easy to mix and sets up well in about 4 hours.  Not cheap but you can get quite a few nice molds from one package.  If you do two part molds you would need to purchase some mold release agent as well.

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9 minutes ago, Chariots of Fire said:

If you do two part molds you would need to purchase some mold release agent

Good Sir!

   I am in need of said " silicone to silicone" mold release..... do you have suggestions ....seen a few listed & have been pricey.

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Micro-Mark does have it.  I am not sure if ordinary silicone spray would work or not.  I have not experimented with it.

 

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I've been making molds for 20 years...I always use petroleum jelly for rubber to rubber release. Never had a problem. All you need is a thin coat!

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I tried the white Smooth-On resin and it worked pretty well, except that both bottles needed to be shaken before use. This gave me a lot of problems with bubbles forming once mixed, and I don't have a pressure pot, so I switched to the Alumilite slow set. So far I have less bubble trouble.

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I've used Smooth On resin for 10 + years. The secrete is to pour parts A & B in their individual containers and wait a bit for the bubbles to go away.  If then  you use a pressure pot, you will get excellent parts. I also use petroleum jelly for a release agent.

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Will coating the part to be casted in WD-40 work?

 

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On 6/27/2018 at 7:13 PM, BigTallDad said:

Will coating the part to be casted in WD-40 work?

 

Or perhaps cooking spray, such as PAM

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I use Smooth-On and baby powder as a release agent.

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13 minutes ago, BigTallDad said:

Or perhaps cooking spray, such as PAM

When I was doing All American Models, I simply used Vaseline petroleum jelly, about 1/4 tsp of that to a 4oz jar of ordinary enamel thinner--to coat the cavity and top surface of the first half of my molds, worked EVERY time without fail.  Nowadays, on the rare occasion that I might duplicate a model part for a project, I still use it and it still works.  Very inexpensive too, I might add!

Art

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Alumilite has a 2-part silicone putty that is VERY easy to use. You knead it together, 50-50 by weight or volume, press it over what you want, and it's ready to use in about 15 minutes. You can use only what you need. One pound--a lot of the stuff--is $30 at Hobby Lobby but I've used the 40% off coupon on two boxes of it, which should last me a LONG time. MUCH easier to use than measuring and mixing liquids, and building up dams to pour them, and so forth. Great stuff! 

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Posted (edited)

Polytek Plat-Sil 71-11 silicone & 1512X resin is what I have been using for years. Mold making & casting in a 2 gal. pressure tank, no vacuum or mold release needed. The resin is white, color differences are due to the lighting in the photo.

Resin copy of a scratchbuilt 1949-1950  Merc. door handle fresh from the mold. The aqua colored thing is the mold.

5b36f5d05dfc9_door_handle1.jpg.3603f188b1b56994cd5f6619e03ce26a.jpg

After a little cleanup.

merc_cranks.jpg.57882029489506eb2e5ab5f4f126ff1c.jpg

Resin copies of scratchbuilt 1949-1950 Ford interior parts.

ford_cranks.jpg

 

After black enamel & Alclad II chrome.alclad1.thumb.jpg.f0b76eebd022ad95f0ad33bab36ef04a.jpg

 

Resin copies of scratchbuilt flipper hubcaps & 1935 Olds side hood trim.

castings.thumb.jpg.a06bfd72c97aba7081a76e3bb8e89109.jpg

Castings come out as smooth & glossy as the patterns are.

 

 

Steve

Edited by sbk

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21 minutes ago, sbk said:

Polytek Plat-Sil 7 1-11 silicone & 1512X resin is what I have been using for years. Mold making & casting in a 2 gal. pressure tank, no vacuum or mold release needed. The resin is white, color differences are due to the lighting in the photo.

merc_cranks.jpg.57882029489506eb2e5ab5f4f126ff1c.jpg

 

After black enamel & Alclad II chrome.alclad1.thumb.jpg.f0b76eebd022ad95f0ad33bab36ef04a.jpg

 

 

Ah yes. THIS is the kind of quality to strive for. Beautiful work, Steve.  :D

Did you make the masters as well?

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Thanks....it's been a long day. I've been editing this post for the past 15 minutes or so.:blink: Hopefully, the version I saved is correct. Yes, I did the masters on all of these.

 

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On 6/25/2018 at 6:26 PM, Chariots of Fire said:

Micro-Mark sells 50:50 two part mold making RTV.  it is easy to mix and sets up well in about 4 hours.  Not cheap but you can get quite a few nice molds from one package.  If you do two part molds you would need to purchase some mold release agent as well.

Mold release for making two-piece molds is as close as your medicine cabinet--for over  a decade of commercially casting in resin, making 2-part RTV rubber molds,  the most foolproof mold-making barrier, and the cheapest, which I used exclusively. ordinary Vaseline Petroleum Jelly,  which I added to a 4-oz bottle of ordinary enamel thinner, to make my own mold-release in order to keep the second pour (the inner core of a mold) from adhering to the first (cavity side of the mold) pour.  Worked without fail every time.  

Art

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