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Casting Clay


#1

Hi All,

Has anyone in the group ever tried casting with Delft Clay? I’d
love to hear about its limitations and potentialities.

I’d be grateful for any comments, so thanks in advance, Vira.


#2

Yes, I have tried casting with Delft Clay and have had poor
results. The metal freezes in the “sprue” part of the clay and
almost never fills the casting. Once I was able to cast a small
14K gold ball, but that is all the luck I’ve had. I’ve tried
casting in it with sterling and copper also.

If you are looking to do home casting with inexpensive
equipment, you might want to try using cuttle-fish bone (like the
kind parakeets sharpen their beaks on). The castings aren’t
lost-wax quality, but I have had better luck. If you cannot find
instructions for cuttle-fish casting, write back and I will do my
best to try and explain it. Instructions can be found in
"Jewelry - Concepts and Technology" by Oppi Untracht (a very
thorough jewelry book) and “Jewelry Making Manual” by Sylvia
Wicks (not as comprehensive, but easy to follow).


#3

Yes, I have tried casting with Delft Clay and have had poor
results. The metal freezes in the “sprue” part of the clay and
almost never fills the casting.

BIG SNIP…

Sand casting is an aquired skill… The fineness of the delft
clay requires air vents in the mold, you can get very good
results, but need to set up properly to do simple rings (dowels
and sand-packing tubes… etc). If you put the mold in the oven
and heat it to 200 or 300 degrees, you will be surprised at the
quality of casting you can get. At one point, we took one of the
extra centrifugal casting machines and altered it to accept sand
patterns. We would spin it by hand, very very handy to have
around! I really like sand casting to create particular sizes of
ingots, the ingot quality is better than normal…

Jeffrey Everett


#4

Hi Vira

We have used the Delft Clay casting method for a couple of years
now. The most important thing to remember is that gravity pulls
the metal into the mould so the sprue can not be too thin nor
long. A diameter of 3mm, nothing smaller.

Air vents are important, we put 4 or 5 in with thin channels
coming off the mould, you can always cut them off should the
metal flow into them.

If you are trying to cast rings them make sure you wiggle the
ring slightly to enlarge the shank area because if it is too thin
then the metal solidifies before it has had chance to flow .

Put the sprue into the mould where there is the largest cavity
again so the metal does not freeze too soon.

When melting the metal keep it molten for at least 30 seconds.
This seems to be the minimum time so the metal gets up to a good
temperature.

We have cast a ring of 1 1/2 oz.

This method of casting works well for us, because we usually
make one off pieces. We usually make up a master in wax or wood.

Providing the clay is compacted well you can get very good
definition. We have cast a small shield with the original having
engraving on. The detail has really good.

I met the gentleman who has patented this casting system a few
years ago in a trade fair in the UK. He gave us answers to the
problems we had using this system and they all worked.

If I can be of any further help them please feel free to mail me
personally.

Regards

Andrew

@andrew.berry


#5

One question… Is Delft Clay and sand casting the same thing? I
have been sand casting for a little while and it works well for
me but some of the tips given have helped alot. I have found that
you can’t have too many air vents, clean up is easier than
recasting.

Thanx,
Jim Loveland


#6

Jill and Richard

Thanks for your advice re the Delft Clay. The agent who tried
to introduce me to it spoke as if this was the answer to all my
casting dreams. And at quite a hefty price too (for clay)! I
might even have fallen for it, so thanks to your advice I went
instead and had a look at a demo , where the stuff was being
used. Since you’d mentioned the problem of metal getting stuck
at the sprue I watched carefully, and noticed that the demo
person made a Massive sprue, which ended up almost larger in
size than the item being cast. Having done this, it seemed to
go OK. Couldn’t possibly do very fine work with it though, I
imagine.

So here goes all you Orchid guys, you’ve alternately scared me
witless and given me great hope for doing my own castings. Have
just bought proper casting equipment and jumped into the deep
end with both feet! Wish me luck! I shall doubtless be
screaming for help very shortly.

Excitedly,
Vira.


#7
 Sand casting is an aquired skill...  The fineness of the delft
 clay requires air vents in the mold, you can get very good
 results, but need to set up properly  ...
 If you put the mold in the oven and heat it to 200 or 300 
 degrees...

I have used the Delft system and as along as I remember to follow
the directions exactly, including air vents and size of sprue
hole it works great.

In the oven? I’d like to try this. Do you make your entire sand
casting and heat it up just prior to pouring the silver? What
differences have you detected between the finished casts
with/without the oven heat?

Kathi Parker
MoonScape Creations


#8

Jeffrey,

Thanks for the tips on the delft clay. I did use a lot of
vents, but I didn’t try heating up the mold in the oven. You
have inspired me to give the sand another shot (no pun intended).
I have a lot of scrap just lying around.


#9

Vira,

Congratuations on the new casting setup! I’m sure you’ll be
glad you took that route. I’m still dreaming of the day when I
can afford my own.

Also, for others who are looking for an alternative to
purchasing the whole casting setup: have a casting company do it
for you. T & M Casting in NYC is a very good, reliable place to
use, and they don’t mind small orders. This also has the added
benifit of giving you more free time to design/work on other
projects.


#10

I have used the Delft system and as along as I remember to follow
the directions exactly, including air vents and size of sprue
hole it works great.
In the oven? I’d like to try this. Do you make your entire sand
casting and heat it up just prior to pouring the silver? What
differences have you detected between the finished casts
with/without the oven heat?

I heat the assembled “cope” and “drag” together, and am able to
achieve thinner castings and greater detail.