Delft clay as mold for ingot

Jewelry Discussion
1

I have been reading the responses to the melting gold question and
saw the mention of using Delft clay as a mold for the ingot. I have
heard the term/name Delft clay before but I have no idea what it is.
Where do you get it and how is it used in forming the ingot? Please
elaborate.

Thanks, Tim

2

Delft clay is made in Germany basically used for sand casting comes
in a metal container and aluminum mold frames. However if you want to
use it just for melting, don’t need to buy the frames, you can use
any metal box of the size you need, fill it with the sand dig out the
shape you want or make an impression in to the sand by pressing an
object of the desired shape. I know you can buy Delft clay from Otto
Frei.

Vasken

3

Hi Tim,

A simple Google search will tell you all that you will need to know.

The following is from Contenti’s website (shown below) including
YouTube videos.

http://www.ganoksin.com/gnkurl/ep7z3l

Instructions

Delft Clay Casting Set

The Delft Clay Method is a highly refined form of sand casting that
substitutes genuine Delft Clay from Holland for ordinary casting
sand. The process was invented by Hans Karreman, a Dutch goldsmith.
Delft Clay is much finer than casting sand, providing remarkably
sharp and highly detailed castings in gold, silver, copper-based
alloys, pewter, etc. Castings require very little finishing work.
Once you have cast your piece, the Delft Clay can be re-used. Since
this is a cold-molding process, molds can be made from patterns
composed of wood, wax, epoxy, plastics, and, of course, metal.
Because this is a type of sand casting, it is best suited to
producing castings without pronounced undercuts. A Delft Clay mold
is created in these steps:

  1. Fill and compact the Clay into one half of the aluminum ring
    frame

  2. Remove excess clay with a straight edge (e.g. a flexible steel
    ruler)

  3. Press your original pattern halfway into the clay.

  4. Brush Mica Powder or talcum powder over this surface of the mold

  5. Install the other half of the aluminum ring frame, fill with clay
    and compact

  6. Open the ring frame and remove the pattern

  7. Carve out a pouring channel and vents

  8. Pour in molten metal

The Delft Clay Casting Kit includes 4.4 lbs. of Delft Clay, a 60mm
dia. Aluminum Ring Frame, and detailed instructions. A 100mm
diameter Aluminum Ring Frame is available separately. View the Delft
Clay video for complete step-by-step instructions on the Delft Clay
Method. Made in Holland.

4

Cant believe some of us have not used delft clay so i wanted to chime
in. I love delft clay. Not only can you make ingots with it, but just
about anything else without undercuts. I am very new to jewelry
making and self taught so my initial investment was small. You would
not believe what you can make with the delft clay kit (comes with
aluminum 2 piece mold). There is a large mold and a smaller one.
Until I built my small workshop I was using delft clay and disposable
oxy/mapp gas to make ring blanks, spoons, pendants, etc. I had a
blast and it got me hooked. Steam casting to me is slightly superior
if I need to get fine detail or undercuts But delft clay is so fast
and easy. There is a video or two out there that has demonstrations.
By learning to make things with delft clay and steam casting and a
torch, I was able to put my crumbly school teacher salary into a
rolling mill.

5

Hi Tim,

Here’s the companies website :-

You should be able to get it from any jewellery tool supplier.

Delft clay is basically a fine casting sand.

To make ingots you just need put the Delft clay in a container (a
soup can would do). Ram it in tight, and insert your ingot model. I
use a piece of brass stock gauge for stock gauge, and for sheet I use
copper sheet.

I used a piece of 1mm copper sheet as a model the other day and
poured the ingot out of red gold. The fun thing was that I cast the
ingot economically, I didn’t need the bottom corners of the sheet, so
I cut the sheet close to the final shape that I required :slight_smile:

Definitely not rocket science, basic foundry/casting techniques.

Regards Charles A.

6 
Because this is a type of sand casting, it is best suited to
producing castings without pronounced undercuts.

:slight_smile: Sand casting can produce undercuts, but it requires a little
more work.

One of the tests of a foundry man’s ability is to make a sand mould
of a tea cup, sauce and spoon as a single unit.

Lots of undercuts, and you have to be very careful, one mistake and
you have to start over.

Regards Charles A.