Reconditioning RTV Silicone molds?

Discussion in 'Replica Props' started by Jimbo890, May 3, 2006.

  1. Jimbo890

    Jimbo890 Well-Known Member

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    I have an old Plasil 71-20 mold that has taken a beating. It's outside is still very much alive, but the surface, where the resin met the mold, has turned a slight pale color and to the touch is more stiff and less pliable than the rest of the mold. Any ideas on a method to rejuvinate this mold, or is it on its way to the meat grinder?

    I know mold release agents will extend the life of a silicone mold, but for how long? These things tend to wear out after some time. I was going to try and use this mold a few more times and save myself the expense of remaking the mold.

    Thanks for any tips.

  2. TK1536

    TK1536 Sr Member

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    I seem to recall reading here that putting them in a 250 degree oven for a few hours does the trick.
    I'd like confirmation on that, especially with Smooth-On Oomoo silicon.
  3. AnsonJames

    AnsonJames Sr Member

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    Try silicone oil on the mould - after a certain amount of use the oils will start to dry out and the mould will become brittle.


    <div class='quotetop'>QUOTE(Jimbo890 @ May 3 2006, 02:12 PM) [snapback]1237501[/snapback]</div>
  4. BrundelFly

    BrundelFly Sr Member RPF PREMIUM MEMBER

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  5. Jimbo890

    Jimbo890 Well-Known Member

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    Silicone Oil? Where do I get that? Hardware store? Autozone? Or special order item?
  6. gobler

    gobler Sr Member

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  7. Hadleys Hope

    Hadleys Hope Active Member

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    Dont bake it unless you are going to put frosting and candles on it. :p

  8. fettpride

    fettpride Well-Known Member

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    <div class='quotetop'>QUOTE(TK1536 @ May 3 2006, 09:44 AM) [snapback]1237649[/snapback]</div>

    Don't even bother trying to rejuvinate the Oomoo Silicone when it's gotton tired :lol Meat grinder .

    Smooth-On has some great products, and oomoo is great when you're starting out. But I've lost about
    14 molds made of 30 recently due to age alone. The surfaces even still seemed to be good. But it got so brittle that picking them up they fell apart in CHUNKS . :lol Thy're only 3-4 yrs old, and were treated and stored properly. The shelf life of cured oomoo is just crap. :confused

  9. Galane

    Galane New Member

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    Old thread but if you're planning on keeping molds long term, platinum cure silicone is the only way to go. I have some molds dating back to 2004 and they're still good. If you think of the molds as an investment instead of as a consumable, you'll see the slight cost savings of tin cure silicone doesn't really save much, especially if you have a need to cast an item again at a future time when the tin cure mold will be deteriorated.

    As for baking the molds, most tin cure silicones advise heating the molds to around 200~250F to finish curing. That may also alleviate some cure inhibition problems with some resins. I've found that convection heat using a food dehydrator or countertop convection oven works much better than radiant heat.

    Since I buy platinum cure silicone in 5 gallon buckets, it's no big deal to use some for small, one-off projects. My 97 Taurus was missing some of its vent handles so I made molds of the ones it had then cast a full replacement set, in bright orange. :) Should I get bored with the color in some years time I'll still have the molds to make black ones.

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