Delft clay

[Skieferins]

Hello

I have recently bought a delft clay casting set of rings which have a "Side hole" which is roughly the size of a 50p piece.

When I bought the rings, I was offered a set of rings with or without a side hole...when I asked the seller what advantage the side hole was for, she said it helped when casting flat objects like coins, which is exactly what I bought the delft set for.

However, I looked on YouTube for a video which showed a casting ring with a side hole but no videos are available.

So, can anyone explain ...or share a link...how I use the side hole to cast a coin please ?

Many thanks

[enigma]

Ive never seen these so hoping somebody knows!
Is the side hole large enough to pour through?

[ps_bond]

I've seen casting flasks for Delft that have a pour hole at the side, but not rings. http://www.ottofrei.com/Sand-Casting-Flask.html is one.

Got a picture?

[Didi]

Hi there, I've recently done some casting using the traditional delft clay set - no side hole. I was casting Daisies, not coins but it was a similar flat object.
To make the delft mould the daisy had to lay flat between the two rings. Any object to be cast using the traditional ring has to be of such a design that the two halves of the mould can be separated cleanly. That means you can't put an object in the mould edgeways because you won't be able to separated the two halves. In my case the funnel for the molten metal HAD to be directed to one face of the daisy. There was no option but to sacrifice detail on one face of the daisy. This wasn't a problem for my design but the backs of the daisies needed significant cleaning up and any detail would have been lost. I'm thinking that a side hole would enable one to create the funnel to go 'edge on' to the coin.
Does the side hole come at the junction between the two rings?
If it does, my guess, and this is all I'm offering, is that you use the side hole to create the pouring funnel. The molten metal will effectively come in at the side rather than down onto a face. This will enable you to create a mould in the normal way, making sure you've got your air vents etc. but then, instead of creating the pouring funnel at the top, use the side hole to create it. This would, I think enable you to get a clean face on both sides of the coin.
I've tried to include a pic of the result of pouring from the top, but for some reason I can't make the photo small enough to upload. Have look on my blog under 'step by step -daisy chain necklace' and you will see the large sprue projecting from one face of the daisy. If I could have poured from the side I would have preserved both faces.

Hope this is helpful and not too rambling. Good luck.
Didi

[Vos]

If it's the ones I looked at prior to purchasing mine (without) it is indeed a pouring hole

[mizgeorge]

Slight thread hijack - but can I just say how much I love the finished daisy necklace Didi - I was admiring it only yesterday :)

[caroleallen]

I'm going to hijack this thread too to say how much I enjoyed reading your blog Dee. The delft clay bit was very interesting to anyone who's struggled with it, as I have.

[Tabby66]

Another one hijacking your thread Didi, today how much I enjoyed reading your blog and how helpful the delft clay process was!!
The necklace is gorgeous, but I absolutely love the bracelet!!

[trialuser]

Have to say also, brilliant blog, could read ones like that all day, really inspiring.

[Didi]

George, Carole, Jill and Trialuser. Thank you so much for your very kind comments. To have such wonderful jewellers as yourselves like my stuff is, well, it's a bit amazing. Thank you.
Didi

[vernon]

What a brilliant set of instructions, pity you didn't have photo's of the pour Ha Ha! very informative I am trying to cast a 3mm thick ring and cannot get it to cast yet. I think you are right lots of air holes and big funnel. Every time I cast the silver freezes before filling the mould, still try again. But brilliant walkthrough.

[Didi]

Oh Vernon - I feel your pain! The operative word I think is DUMP the molten silver not POUR the molten silver! To pour implies steady whereas what you need is speed. The problem I found was that it's kinda counter intuitive to tip the scorifier as fast as you need to. Some how just chucking red hot metal into a mould seems wrong. Try and dump it into the mould as fast as you possibly can. Keeping the heat on the silver as it goes in seems to make a difference.
Thanks for liking the blog.
Didi.

[vernon]

As I work in my conservatory I cannot fit a centrifugal caster in so I am persevering with the clay. Do you think one of the thin circular scorifiers would soak up less heat, maybe?

[Didi]

Hi Vernon.
Centrifugal caster! ha ha! That would be a pipe dream for me too. I don't know wether the scorifier soaking up the heat is a problem. Mine got so it glowed read as I heated it up. I use the 2" scorifier that Cookies sell, it seems to work ok for me but I do use my seivert torch with a medium burner to heat it. Do you have a big enough torch? It did work better when I built a little kiln with fire blocks to keep the heat in. Melting the silver does seem to take longer than I expected it to though. The silver has to really wobble and slosh around in the bowl before you're ready to pour. Other useful things I found out - If you remelt silver several times it loses it's ability to flow cleanly. Several of the later daisies didn't fill the mould and I think it was the degraded silver rather than technique. Borax powder is essential, not a luxury. Rest the scorifier right on the mould over the funnel before you pour it and then whip it in. Patience is a virtue - or so I'm told!
Good luck.
Didi

[ps_bond]

When you're pouring the silver, it's best to have it at what's termed "superheat" - where rather than just being liquid, the molten silver is spinning in the scorifier. Keep the flame on the lip of the scorifier as you're pouring too.
Centrifugal casters use centripetal acceleration to force metal into the mould, vacuum casters use air pressure, steam casters use steam pressure but all the poor Delft system has to rely upon is the hydrostatic pressure of the molten metal. Hence large casting spouts, fairly chunky sprues and relatively simple moulds...

[vernon]

That's all great advice. I use the Smiths Little Torch with the melting tip and I am sure that I do not wait long enough for the silver to get hot enough, Impatience! I really should take longer but I want to see the result!

[ajda]

What advice can anyone give re sourcing Delft clay of reliably good quality at reasonable price? Reputable jewellers' suppliers sell it at prices that seem steep to me for a bit of sand and oil - or am I underestimating what goes into it? A while back I bought a couple of kilos relatively cheap on eBay and did some experimental casting with pewter, but I don't want to risk too much silver if the stuff isn't what it should be... Does anyone make their own?
Alan

[Wallace]

I posted this link before, but it never hurts to repeat I guess.

Petrobond is a good and economical alternative to Delft. It is reliable and produces great results.
http://www.mindsetsonline.co.uk/Catalogue/ProductDetail/petrobond-sand?productID=db57155a-95db-4e35-87a4-8b3fa4dcdf95&catalogueLevelItemID=00000000-0000-0000-0000-000000000000