Is there an inexpensive way to enlarge molds? (for small parts)

J

JCarey

New Member
I'm working on some pendants and I have a piece that I want to enlarge to almost twice the size. I tried googling for a solution, but I only found options for large quantities with high prices, very short shelf-life, and questionable reviews. Does anybody have suggestions for something inexpensive that works well for things that are about coin-sized? Or something a bit pricey but that can be saved for years and used for many small projects?

And while we're on this topic, how about something for going the opposite way and shrinking things?

Thanks!
 
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IIRC there is a molding material that will shrink in scale but I don't think there is anything that will enlarge one.
A lot of resins and silicons shrink by themselves (that's why recast are always smaller than the original)
 
Holluba said:
I don't know how you define inexpensive, but there are two products that may be of interest to you.

Hydrospan - does exactly what you're asking for.
http://www.sculpt.com/catalog_98/CastingMaterials/HydroSpan.htm

And then there's Hydroshrink, this does the opposite of the above product.
http://www.sculpt.com/catalog_98/CastingMaterials/HydroShrink.htm

You can decide whether you consider these products as inexpensive or not, but the smaller batches do seem to be priced fairly reasonably.
Click to expand...

The smallest they offer is 3 quarts (for $84.99 and I'm not sure about shipping costs). That's a lot when my piece is the size of a nickel, and the Hydrospan would go bad before I'd want to do another project with it.

Has anybody tried soaking a silicon mold in mineral spirits, naptha, or gasoline? I've seen this mentioned, but no instructions or specific products.
 
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We have enlarged pieces by casting them in silicone and then soaking them in diesel fuel. This causes the silicone to swell up, and then you can pull a new mold off of the swollen casting. To double in size you would have to repeat this process a couple times, because it doesn't continue swelling past a certain point.

Coin shapes work pretty well for this, but objects with thick and thin areas can distort because the thick/thin areas swell at different rates, and you may lose proportions.

We did try soaking a mold in silicone; and it worked, but it took a long time (weeks) to swell up enough and it made the mold rather fragile to handle. Not to mention stinky!
 
I've tried Hydrospan, and it's pretty tough stuff to work with. My experiment was a failure.

What's the part?
Maybe you could draw it in 3d and then have it printed at a larger scale.

Dan
 
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