Using Silicone Mold in a Pressure Pot?

[vtgaryw]

Was wondering if anyone has tried making a "frame" that a silicone mold could fit in so you can use it under pressure? And if so did/could it work? It'd be a great way to pressure cast more blanks at a time without having to invest in more rigid molds.

-gary

 

[Dieseldoc]

Gary:
All I use is a 1/4 ply wood frame glued wth hot glue and it works every time.
Charlie

 

[bmachin]

Maybe I'm being a little bit dense here, but I don't understand the need for the question. There are all sorts of silicone molds commercially available out there for casting pen blanks. and none of them require any sort of frame and all work quite well under pressure as far as I know.

Any enlightenment would be appreciated.

Thanks,
Bill

 

[Robert Taylor]

Maybe I'm being a little bit dense here, but I don't understand the need for the question. There are all sorts of silicone molds commercially available out there for casting pen blanks. and none of them require any sort of frame and all work quite well under pressure as far as I know.

Any enlightenment would be appreciated.

Thanks,
Bill

there are many thin/flimsy silicon molds in the kitchen dept at many stores. a support frame would be a plus indeed.

 

[Dieseldoc]

Maybe I'm being a little bit dense here, but I don't understand the need for the question. There are all sorts of silicone molds commercially available out there for casting pen blanks. and none of them require any sort of frame and all work quite well under pressure as far as I know.

Any enlightenment would be appreciated.

Thanks,
Bill

Bill:What we are making reference to is molds like the one sold by . ETSY 3- blue silicone mold for pen blank casting. These are the one we purchased several years a go $49,00 for three, and the need support. I have cast over 100 blanks with these mold. How saying that the new type molds which I think you are making reference to don't need extra support.

Charliie

 

[bmachin]

I was thinking more along the lines of those made by Fred Wissen (ptownsubbie) and others which are much more substantial. I didn't realize that purpose built blank molds that flimsy even existed.

I think there has always been some concern that using silicone under pressure somehow changes things--like the pressure will somehow cause the silicone to deform and somehow ruin the casting. Unless there are bubbles in the silicone, it ain't gonna happen. If you can get the pour into the pot intact, it's going to survive intact. In short, the pressure pot should not have any effect--although I'm willing to be corrected subject to experience.

Seems that this question has come up every couple of years or so.

Bill

 

[1080Wayne]

The pressure exerted on the mold in a pot is uniform on all sides , so no deformation of the mold is caused by it . The only cause of deformation is gravity acting upon the resin put into the mold . If the mold is too thin to resist that , some support would help . I regularly fabricate mold extensions on odd shaped pieces or individual pen blanks using duct tape , without problem .

 

[Skie_M]

Try taking some thin cardboard and duct taping it around the sides of the mold ... that should add enough support that it will stand up properly without adding a bunch of volume or weight to your mold, and should also remain flexible enough that you may demold from the silicone with no issues.

 

[vtgaryw]

The pressure exerted on the mold in a pot is uniform on all sides , so no deformation of the mold is caused by it . The only cause of deformation is gravity acting upon the resin put into the mold . If the mold is too thin to resist that , some support would help . I regularly fabricate mold extensions on odd shaped pieces or individual pen blanks using duct tape , without problem .

That was absolutely not true in my experience. I had tried using a pink Smooth-on type of mold, and it deformed enough to ruin a casting. The pressure may be uniform from all sides, but the different walls can deform different dependent upon their thickness, length of the section, etc.

-gary

 

[jalbert]

I poured this silicone mold last weekend and used it in my pot without any stabilization. I didn't have a problem with deformation issues ¯\_(ツ)_/¯

 

[its_virgil]

Make a frame and move on and enjoy casting. I use silicone molds on my pot with no problems. They are not home made. Cast at 45 psi.
Do a good turn daily!
Don

 

[vtgaryw]

I poured this silicone mold last weekend and used it in my pot without any stabilization. I didn't have a problem with deformation issues ¯\_(ツ)_/¯

I'm talking about Tube-In molds. I talked to "I forget his name" from Royal Palm resin, and he confirmed that soft tube-in molds are not a good idea in pressure pots.

Gary

 

[its_virgil]

Not sure what he means by soft. I use the molds sold by Fred Wissen with no problem at all. Love them.
Do a good turn daily!
Don

 

[Curly]

That is contingent on the pressures you want to cast with and the type of mould. If it is one with built in plugs it will leak past the plugs when you get to moderate pressures. Ones with separate plugs will take more pressure. If you make your own moulds with a hole through the plug it will equalize the pressure and be better at resisting leakage. You need to ask yourself why you need pressures that will distort for tube in casts? Most of the time it is totally unnecessary but the more is better mentality prevails. Any side distortions are insignificant and won't matter when you turn the pen.

Want to know how much pressure given mould will take? Put water in it and test to a given pressure and then remove to see if there is any water in the tubes. Repeat with a few more pounds each time until you get a leak. Back off a 5 pounds and you should be good with resins. Still can't get to the pressures you want? Make the mould from denser silicone.

 

[1080Wayne]

The pressure exerted on the mold in a pot is uniform on all sides , so no deformation of the mold is caused by it . The only cause of deformation is gravity acting upon the resin put into the mold . If the mold is too thin to resist that , some support would help . I regularly fabricate mold extensions on odd shaped pieces or individual pen blanks using duct tape , without problem .

That was absolutely not true in my experience. I had tried using a pink Smooth-on type of mold, and it deformed enough to ruin a casting. The pressure may be uniform from all sides, but the different walls can deform different dependent upon their thickness, length of the section, etc.

-gary

Thinner wall thicknesses will certainly deform more than thicker ones under the weight of the resin being cast . The other factor is that curing reactions are exothermic . The heat will soften the thinner sections more than the thicker ones .

 

[sbell111]

The pressure exerted on the mold in a pot is uniform on all sides , so no deformation of the mold is caused by it . The only cause of deformation is gravity acting upon the resin put into the mold . If the mold is too thin to resist that , some support would help . I regularly fabricate mold extensions on odd shaped pieces or individual pen blanks using duct tape , without problem .

That was absolutely not true in my experience. I had tried using a pink Smooth-on type of mold, and it deformed enough to ruin a casting. The pressure may be uniform from all sides, but the different walls can deform different dependent upon their thickness, length of the section, etc.

-gary

If the silicone wasn't degassed properly, then it could have bubbles within it that are compressed under pressure, resulting in mold failure. I doubt that this issue exists with those molds that are available commercially.

 

[MRDucks2]

Equal pressure on all sides will not deform a solid.


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