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Delft Clay Casting

Antone familiar with Delft Clay Casting? Is it a good alternative for
someone learning casting?

Bob B

I’ve worked with Delft Clay Casting, and I’ve had a lot of fun with
it. You can order it from Rio Grande or Swest and get a video
that’s pretty good. I’ve done a few demo’s too. It’s certainly more
limited than centrifical or vacumn assist casting, but then it costs
a lot less get into it. Probably not very usefull for fine jewelry,
but certainly it has a lot of applications for art metalsmithing.

David L. Huffman

Hi Bob, I don’t know how good an alternative it is, but it is quick. I
started out casting with Delft clay using both sterling and fine
silver and I still use it sometimes even though I now have the
equipment for lost-wax investment casting. Maybe I just haven’t gotten
the hang of investment casting yet. One thing I like (and one of you
chemists out there please correct me if I’m wrong) is that when the
delft clay burns upon pouring it removes oxygen that might otherwise
cause oxidation of the silver, leaving a surface that almost requires
no pickling. However, it is only good for items without undercuts and
without massive surface detail (you will have seams). Good luck with
it, I have made some awfully nice peices (for a beginner at least)
using Delft Clay- just remember it’s limitations. Michael Bowles Eye of
the Moon Jewelers, L.L.C.

Actually, Delft clay casting is very good for converting solid carved
waxes and solid carved rings into silver models ( this means waxes
that are not hollwed out on rings and that there are no undercuts ) If
the part or wax model can be lifted out of the clay without disturbing
the clay, then it will be castable.If you see parts of the clay
lifting out with the wax, then this is considered an under cut.In this
case, clean the area where the undercut was in the clay… cast it
into metal … then clean up the area that you modified in the clay as
this will now be unwanted metal.

This is an excellent way for beginners and models makers to create
their metal models using wax and can also be used with solid metal
models to reproduce usable shanks and parts. Daniel Grandi Casting and finishing for
designers,stores and people in the trade. We have a 24 hour turn
around capability on cast items in gold between now and New Years for
those who need it.

In all respects, Delft clay casting is similar to sandcasting, but
allows finer detail. The casting molds supplied only allow horizontal
pours, which is restrictive. You can use a regular sandcast or
homemade mold with a vertical pouring gate to allow for either
vertical or horizontal pouring. It is a good method of low-tech
casting, as long as you get good directions for sandcasting, but it
will not allow for very thin sheets or extreme undercuts. To learn how
to cast effectively, begin with the simplest patterns you can find,
the more uncomplicated the better. Carving wax masters can be made,
but it must be the extremely hard carving wax which is green. Almost
all other waxes are either too sticky (causing the clay to be lifted
and destroying your negative mold) or unable to be carved successfully
with any amount of fine detail. Since the clay is finer than sand, it
is able to pick up details such as etchings, as long as there are no
undercuts to impede the release. Once you learn to do simple
castings, then you can progress to learning how to pack hollow forms
and 3-D objects. If you can find someone already familiar with
sandcasting, go learn from them. It will greatly shorten your learning
curve :-}

There are 2 important points you must remember: The first is that
your pouring gate must be a minimum of 5mm in diameter, which is only
slightly smaller than the diameter of a pencil eraser. Second is that
you must be scrupulous about packing the pouring gate and vents, as
well as making sure they are free from debris. If the clay is carried
into your casting when it is poured, it will ruin the casting.

Have fun learning. You don’t really lose much with casting other than
time. The flops go back into the melting pot.

Bob, There was much discussion within the past two months about delft
clay casting. Check the Archives and “delft clay” as search words.

Orchid Rules!..Karla


I’ve been casting sterling silver using Cuttlefish bone for about a
year now with reasonable success. I’ve now bought a Delft Clay
casting kit to try and get some better quality castings but I’m
having great difficulty getting the mould to fill properly no matter
how well I vent the mould.

can anyone out there with experience of this casting system give me
any pointers.


You’ll ‘probably’ get a lot of helpfull response and there is quite a
bit in archives. Basically, you need more and betterplaced vent
holes. I don’t know about Cuttlefish bone but, when you pour molten
silver or gold into Delft Clay, the air must come out of vents that
you create. Pour where the mass is largest and vet at every point or
extremity. Excellent process for “one-of 's” Good luck,


    can anyone out there with experience of this casting system
give me any pointers. 

I’ve recently had similar difficulty with a thin shanked ring a
student tried to cast this way. The model was a hard wax ring shaped
much like a typical signet ring, sprued to the heavy top and vented at
the bottom, and while the top came out well, the shank was incomplete.
From mem ot was about 1.5mm thich, half-r section. Not heavy enough to
allow the quickly cooling stg to get into the thinner parts. Tried 3
times, and it was better on the third (tho still incomplete) when we
did a combination of two things: beefed up the feeder sprue to 4.5mm
and wiggled the model around to make the cavity larger.


B r i a n � A d a m
Auckland N E W Z E A L A N D


The problems may be:-

Delft clay chills the cast a lot quicker than Cuttlefish so go for
thicker, simpler pieces first. Are you pouring through the flame to
keep the metal as hot as possible? I cut a pouring hole at least 4mm
in diameter and as short as possible - say 1cm (half an inch) at most.
It is important to hit the big areas of the model with a fat ‘sprue’.

Are you venting out to the top of the mould? (I use a high tech
straightened paper clip for vents). If I don’t see smoke from the
vents I suspect an incomplete cast. How much metal is in your button?
I reckon an at least as much as is in the model and a lot more on
small pieces. One of these days I’ll photograph a casting session but
I haven’t got enough hands!


Andy Parker, Agate House Lapidary
Ulverston, Cumbria, England
Tel: 01229 584023

I cast with Delft fairly frequently. When I first began, I wasn’t
very successful with it either. I did discover several things,
however. First is the packing method. Unlike typical sand casting,
where you riddle it and pack it quite tightly, with Delft I seemed to
have better luck with just overfilling (making a mound) and packing
once before striking. I think you can’t pack it too tightly because
the grains are finer than sand. Second, the size of the pouring gate
is essential. It has to be fairly large (about 5mm) so the metal
doesn’t cool before it gets to the end of the model. On some things
which will pour better in a vertical plane, I use my sand casting
mold. Third is the placement of the air vents. These are best placed
at the opposite end of the main pouring gate, so the force of the
expanding gases help push the metal to fill the mold completely.

When I first began with the Delft casting, I also experimented with
the same model, over and over. I took notes on what I did differently
and how it affected the casting. With this method I started learning
how to pack different types of models successfully. Sometimes it
required placing the pouring gate and air vents in different places,
usually aiming the pouring gate for the very thickest or largest part
of the model, and the air vents towards the smaller parts of the model
and as opposite as possible from the pouring gate.

If you still don’t seem to be making progress, contact me offline
with more specific details about what you’re trying to cast and what
your results have been. Maybe I can help with some shortcuts on the
troubleshooting part.

Hello Bob,

About Delft clay casting, I think you should heat up the sterling
more. The heat absorbance of the clay is much higher than the
Cuttlefish bone. The opening to pour in should be at least 5 mm.

Martin Niemeijer

Hi Bob, Without more specific details of the problems you encounter,
and of the sort of objects that you are trying to make, it is
difficult to decide how to improve on your technique. However, in my
experience by far the most important thing is that the silver is
really very hot, and that you continue to heat it while pouring it
down in the funnel. For flat and thin objects the ratio of volume to
surface area is very unfavourable, so that heat is lost quite rapidly
to the Delft clay and your mold may fill incompletely. In the case of
thin, flat objects it is my experience that it pays off to see to it
that the Delft casting rings are level (I even check it with a spirit
level), particularly when objects are relatively large so that the
silver has to travel an appreciable distance: one part up-hill if the
rings are not level, another part down-hill, where the former
obviously is at a disadvantage. In the case of larger and flat
objects position the funnel in such a way that it will be about at
the centre of the mass of of the silver object. My wife and I
initially had great difficulties in using the technique for making
thin objects that we could then enamel (cloisonnE9 or champlevE9
technique), but by paying attention to these points our failure rate
is now low. We have kept a log of all our failures, analysed these,
and this boiled down in a detailed description which you can look at
if you wish (, click on the Union Jack for
the English text).

Good luck, Philip Quanjer from Holland.