There has been alot of recent items about delft casting. I’ve never
used this technique. Is it a technique that’s useful for certain
things? Why would one use delft as opposed to lost wax, for
instance? Thanks KPK
Delft clay is usefull for duplicating items with little or no
undercut. One of the best usees of Delft is to replace a lost earring.
If the remaining one does not have much undercut, you can make a new
one in just a few minutes (plus solder post). You get fairly good
(better than I expected) detail. If you are just making one (or a
very small quantity), it’s quick, good quality, and very inexpensive.
Good luck, Regis
Hello kpkelly
Delft casting just like sand casting. what they use for casting iron,
steel etc… However the trick is to find good sand and a good binding
material. This technique is already used since the bronze age. But
there was a guy in the city of Delft who has taken Brussels earth ( a
very fine limy sand) and bind it with some oily stuff. I do not know
if he had help from steel casting firms, but he was the one to
introduce it with the two rings . This he published in the jewellery
branch and since then it is called Delfts clay casting. But it is a
name only used in the gold and silver branch. If you ask Iron casters
they will not recognize this name But I think that they are using this
limy sand and binding material for years.
Martin Niemeijer
About Delft casting I have been following the discussions about Delft
casting. One of the statements was that you cannot use the technique
for casting thin objects. That depends on how thin you want to go. My
wife and I, after extensive experiments, have now adopted the
technique to cast silver objects for either champleve or cloisonne
enameling. To that end we first make a design, transfer it onto an
overhead sheet, the expose it by UV light in contact onto a piece of
UV sensitive polymer (in fact MiraclonAE with metal back). The
unexposed polymer is then washed out with a soft brush in lukewarm
(about 35 B0C 3D 32 + 35*9/5 3D 95 B0F) water (be careful not to
continue not to continue too long, say <4 min, as the exposed polymer
will soften and detach), dry it carefully with a hairdrier, then give
it a ‘long’ UV exposure to harden the polymer, and you have a
negative replica of the drawing. The minimum thickness of the washed
out polymer is about 0.15 mm (0.06"), so we paste pieces of sheet
(anything that is stable and stiff enough to survive the following
steps) using double-adhesive tape, to increase the minimum thickness
to 0.7 mm (0.28"), depending on the object. The minimum thickness
depends on the object and its dimensions (see below). Next one makes
a matrix in Delft clay as usual, prepares the pouring gate (make it 5
mm wide or wider, see to it that none of the clay can get adrift
while pouring the silver), be generous with the number and diameter
of the vents (make sure, prior to casting, that these are not
obstructed by pieces of clay!). The pouring gate is a point of
pivotal importance: in preparing it one may inadvertently cause the
clay to encroach on the cavity, so that when pouring silver the
entrance is ‘obstructed’. So before closing the two rings again, put
your mold in it and press it against the pouring gate to make sure
that the latter does not bulge. We have learned that prior to casting
it is very important indeed to carefully adjust the clay so that the
matrix is as perfectly horizontal as you can get. Simple geometrical
considerations show that even a slight angle can cause two ends of
the mold to differ in height by 2-4 times the thickness in a
horizontal plane. In that case the highest parts often do not fill up
properly, particularly when the object is thin.
When casting such thin objects you are immediately punished for not
sufficiently raising the temperature of the silver: it has to travel
a long distance compared to the thickness of the mold, so it cools
down very rapidly and does not reach the perimeter of the object
If the final object is ‘large’ we may have to make it a bit thicker,
if it is small 0.7 mm suffises. For example, one object is a giraffe
6x2 cm (2.36x0.79") with a few cloisons, worked fine. For champleve
thickness is somewhat less demanding, because the average thickness
of the matrix is greater, and this influences the ratio of mass and
surface area favourably, so that the silver cools down somewhat less
rapidly.
We have described the ins and outs, including photographs of what can
go wrong and reasons for it, and put it on the internet in an
experimental site. You would not believe it, but being of Dutch
tongue I have had the audacity of writing it in … Dutch. If there
is interest I can translate it into Denglish (3D Dutch English).
We have used the technique for various cloisonne objects. One is a
necklace of tulips (how Dutch can you get) and of cats, with pendants
of different sizes: using a computer to design makes resizing the
same object, mirroring, turning a positive into a negative of the
object, a breeze. Philip H Quanjer, @Philip_Quanjer
I’m busy building a fantasy steam punk piece called the Palindrome
Cannon.
I had to do some Delft Casting so I did a small HIDI (how I do it)
on my Ganoksin blog.
Check out
https://www.ganoksin.com/gnkurl/ep802t