Thank you very much for your answer.
I have taken time to answer to you because I was making tests.
Now, the situation is better. I use plastic frames around the molds.
The last point to solve is to find something to avoid that the resin
stick to the plastic frames because I still have small leakages.
I keep your idea of using resin for making a new frame for molds. I
think I will test it soon.
--- In casting@y..., "Mike" <mikejac@m...> wrote:
> From: "pat72creation" <moulage@9...>
> > Just a question : how do you use your molds during casting ? I
> > do you use a frame around the molds ?
> Hi Patrick,
> I suppose that if a mold were humongous (very, very large), one
> to use some sort of frame in order to avoid having to allow for
> massively-sized side walls in the RTV mold.
> For the types of molds that I do, most are less than a square foot
> about 30 x 30cm. I've found that in that sized mold I need to keep
> outer mold walls at least .5" to 1" (1.25 to 2.5cm) to have the
> its shape during casting.
> The deeper the mold, the thicker the mold walls, because the mass
> resin will exert greater pressure against the mold walls. I have
> the ol' budget, so at some point it will involves less cost to use
> rather than increase the mold wall thickness.
> I know that some of the folk here do truly massively-sized castings,
> especially in the movie and museum-related fields, and I would
> they use frames a lot. The largest casting that I've been asked to
> so far, has been a sign that measures 2' x 3' (61 x 91cm).
> Because it would require a shallow mold for the back piece, I wasn't
> concerned about the extra .5" or so I would have had to add to the
> walls. Now, had it been several inches deep, I would not have had
> thoughts about building a frame to hold the mold in shape during
> Hmm... just had an idea. One could build a box around an already
> mold, and fill the space between the mold and the box with resin.
> between the box and the mold would not have to be very large. When
> resin cured, one would have a perfectly fitted resin "jig" to brace
> during casting. (Note: Be sure to use a release agent on the inner
> of the box!)
> Demolding might be a challenge, but one could always powder the
> slip it back into the "jig" for the next pour. And, it would
> better to pour the "jig" with the mold face up. The table surface
> mold supports the bottom of the mold, one is really only concerned
> supporting the sides of the mold, and the open bottom of the "jig"
> allow for easy removal/re-insertion of the mold itself.
> Hmm... another idea. The "jig" could also be reusable for other
> one used it (empty, of course) for the mold box when pouring a new
> I shall call this creation... the "Jackson Jig", or "JJ" (jayjay)
> short! <grin>
> (Then again, it's really only a variation of the mother mold
> Back to sanity... :O)
> TTFN - Mike Jackson
> Casting Fool & Son
> Augusta, GA USA
> http://www.cfnson.com (reserved, not active)
> Temp URL: http://www.melas.org/cfnson