Cold cure silicone moulds.

[Lucie]

Hi all,
Have any of you ever had any experience of having cold moulds (not vulcanised rubber ones) made directly from wax masters?
Can you tell the difference between a direct cast from a wax and a cast from the mould?
Thanks in advance :)

[Gemsetterchris]

I've done a couple & they come out fine. I think they cast first anyway & then make the mould?
The best way is to clean up a casting & then get a mould from that.

[Lucie]

I've had a problem with cracks appearing in the casts, so one caster suggested that I could get a cold mould made from the wax master, they can then re-cast as many times as they like to get a flawless cast (no charge if a cast fails). Chances are it'll probably cast right first time anyway, but I have deadlines and can't keep remaking waxes - Just had a very sleepless weekend after I got a phone call at 4pm on Friday to say that a whole casting run had failed & all my masters had been destroyed :(|

[Dennis]

Once this crisis is over, find a new caster Lucie. Failed casts should be quite rare and in they have them they should have a back up in place, not pass the buck to you.

[Lucie]

Hopefully sorted Dennis. Unfortunately, my existing caster has now gone on holiday for the whole of August, so I spent the weekend making up 10 identical master waxes.
I've sent 4 to Merrells and 4 to Jewellery Casting Scotland (Wallis Hunter) for direct casting from the masters.
I've also sent a couple to Weston Beamor who are going to make a silicone from the wax so I can make a comparison - they were the most reasonable for the service.
They have assured me that there will be no shrinkage, but I wanted to see if there was any loss of detail.

At this rate, I'll be able to give a pretty comprehensive comparison of just about every casting company going. I just wish it wasn't necessary!

[Dennis]

Good for you Lucie, there is no excuse for poor service, but jewellery makers seem to be particularly disrespected.

[Tabby66]

Not sure if this is helpful Lucie, but my understanding is that if you supply a wax, then it is a one off use, since it will be burned away during the casting process, the risk therefore lies with the person supplying the wax.....using waxes with no mold being made, therefore has an inherent risk.....if a master mold is made, then the process is repeatable and though the initial outlay may be slightly more, the risks and additional work can be avoided.

There is no shrinkage with silicone moods.

I look forwards to hearing how the various pieces work out :)

[Lucie]

Thanks Dennis :) I'm exhausted now! Casters definitely seem to be a breed of their own, especially if the bulk of what you make is "only" in silver.
I've had several actually ask me if I really only want things in silver (with the note of disdain not particularly well hidden).

[Lucie]

Not sure if this is helpful Lucie, but my understanding is that if you supply a wax, then it is a one off use, since it will be burned away during the casting process, the risk therefore lies with the person supplying the wax.....using waxes with no mold being made, therefore has an inherent risk.....if a master mold is made, then the process is repeatable and though the initial outlay may be slightly more, the risks and additional work can be avoided.

There is no shrinkage with silicone moods.

I look forwards to hearing how the various pieces work out :)

That definitely seems to be the way it works. For gold pieces, making a mould is worth it - I can absorb the £18, but for little silver charms, etc... not so much :(

It might be a good idea to make up 2 x the masters, then get them to cast them one at a time? Then they can use the 2nd one only if the first one fails.

So far, none of the casters think there is anything fundamentally wrong with my waxes, but the guy at Jewellery Casting Scotland seemed very knowledgeable & also willing to spend time discussing it with me (always a plus). He's going to take a look when the waxes arrive tomorrow to see if he can suggest anything.

I'll update on the results from all of them :)

[ShinyLauren]

Wishing you good casting mojo Lucie! Do let us know how it goes and who you get the best experience from.

I've used West One for years and only ever had one duff batch of castings from them. And they don't care a jot that I only make things in silver!

[Lucie]

Wishing you good casting mojo Lucie! Do let us know how it goes and who you get the best experience from.

I've used West One for years and only ever had one duff batch of castings from them. And they don't care a jot that I only make things in silver!

Thanks Lauren - think I need it with my track record lol :) The guys at West One are great (plus they're one of the only casters in Hatton garden that don't disappear for the whole of August! !), but they have no finishing / laser service at all if I'm desperately busy or if something goes awry.
I'm tempted to send off a bunch to Niagara Falls & Nexgen, then I really would have tested them all out :)

[Tabby66]

I use Nexgen and can recommend them Lucie!! If ever (which has been rarely) I have had a problem, they recast without question. I do cast from a mold when casting pieces, so recasting isn't an issue. They have a comprehensive finishing service, but I've never used it, so I can't comment!

[Lucie]

Oh dear - better get making more little wax beads then I can try them out too lol.
Out of interest, do you get cold moulds made? Can you remember how much they are? Weston Beamor is £18.40 plus the vat.
Its handy to have a finishing service available for cracks in castings, etc (or for school holidays whwn I'm running out of hair to pull out ;)

[josef1]

I think You will get shrinkage when you inject the wax into the mould, the mould itself will not shrink the shrinkage amount will depend on how the wax is injected temperature etc and the size of the model

[Tabby66]

I believe (and wait to be contradicted!!) that you don't get shrinkage in the wax (or cold mold), but in the latex mold (which is heated to conform), when taken from the master and it cools it relaxes and expands very slightly and thus shrinkage occurs......

I go directly to a mold cutter and then collect and take to casters.....so my time and shoe leather.......reduces costs!!

[Gemsetterchris]

They probably do shrink technically, but a lot less than vulcanised, & turn out near enough identical.

[Lucie]

If they shrink at all I'll not be happy - they have told me that the casts will be exact replicas.
They're handmade beads to go onto a well known (ahem) bracelet, so if they shrink, they'll be good for nothing :N: