Delft Clay Casting

[BarryM]

I have just had 2kgs of Delft clay and the 60mm aluminium rings delivered from Cookies to try some casting. I have looked at the videos by Andrew Berry on Delft Clay casting (very good by the way) - any tips before I try my first cast?

The intention is to cast some natural products in sterling - acorns, small fossils, sea shells, nuts etc. to make into pendants.

[Dennis]

I don't do it, but the main advice here is to be generous with the thickness of the sprue and to add accessory sprues for a wide piece. Then add plenty of channels for the air to escape, so that there are no dead ends.

Lastly keep heating the scorifier while pouring, so that the metal remains fluid.

I would also add as a note of caution, to do it in a large metal tray, like a roasting tray to protect against spillage. Dennis.

[BarryM]

Dennis, Thanks for the very good pointers - already bought a large metal tray to work in ... just in case ....

[Vos]

My first mistake was making the air holes too small. I've since found a 3mm drill works, but I'm nowhere near an expert.

There is one YouTube video that advises to make the pouring throat AT LEAST 4mm wide. I'll see if I can find it. Other than that, remember to breathe

[BarryM]

Cheers Vos


Sent from my iPhone using Tapatalk

[Vos]

I should add that I'm only casting small stuff so the 3mm vents are adequate for me.

[Hans Meevis]

Natural objects often have many tiny undercuts. Careful with that.
I make my throat 7mm if I can.
I never bother with air lines, the sand is more that porous enough.
Here is some more information .

[enigma]

Thanks for sharing that Hans

I can't imagine not needing air vents, I know with mine if I don't have a big enough air vent in the right place the horses ears don't fill with the metal ? Maybe it depends what shape you are casting?

[Nick martin]

If there's no adequate air vents, then there's nowhere for the hot air to escape to.
This in effect creates air pockets which then stops the molten metal from flowing properly around the mould.

On certain intricate castings, and depending on where you place the sprue, placing your mould on a slight incline can also help greatly.

Nick

[BarryM]

Thanks to all for your input. Tried my first casting today using an old english threepenny piece (12 sided ones). Got a very good result on my 3rd attempt, the main things I found are that air holes are very important in getting a good full cast, and that the silver must be really well melted and then some more. The first couple of attempts I don't think I had the metal hot enough and it was solidifying too quickly.

Overall very pleased and like everything in jewellery making, the preparation must be done carefully and there are no shortcuts if you want a good clean result.