Bramblebush ForumsFAQ
Posted by bruce paul fink on January 11, 1999 at 12:39:48:
To:
rahjaahmina@webtv.net,
I am hoping you can help me. I am looking for documentation for sandcasting that I could date as far back as 1100AD up to about 1550 AD. I am in need of maybe internet addresses or books and their bibliography.
I found your sight in search of the documentation I need. I do hope you can help me. Rahja
Dear Rahja:
This may be a hard one, It's been a long time and I've forgotten so much from back then. The earliest known use of metals but which much documentation is sparse dates back to c.7000 BC with a full development of copper smelting and alloying technology at c.2000 BC. (first with arsenic and later with tin).
Since the sand used was broken away before it was known if the casting was a good one and the sand properties were up to par most of the moments excitement undoubtedly went into the metal,
melt casting and finishing itself. The metal media itself would usually be the prime focus of the success or failure so less attention would be going to the sand investment but it would be saved if successful and repeated by proportions.
To jump back so other readers may follow a bit of this: A general sand mold was composed of a fairly fine sand and a slight amount of clay material to help it hold its form. Minimal water was mixed or "mulled" with it so it was evenly consistent and held it's shape while the metal was poured in. This also means that the sand mold had to be made relatively close to the same time the metal was to be poured and not days or weeks prior.
The mold was used mostly if the positive model shape was
either pressed into the surface of the sand (if fairly shallow) or the sand was sifted over and then pressed or compacted around the positive model. The model had to be removed so there could be NO UNDERCUTS. This made simple, shallow container forms a natural as long as everything was tapering open on top. It also made adding legs to it a natural since they could double as vents and sprues to get the metal into it and allow the air to escape. The other quality of this sand / clay mixture was that it could partially gas out through the very body of the media. (Why the necessary presence of a little water to make it stick together was no problem). Just take a handful, compress with closed fist and if it keeps your hands shape (wet enough) without sticking to your finger prints (dry enough) you've got the beginnings of the right stuff.
It certainly was also noted early in the quest that markings, scratchings or indentations in the sand body made for great reverse form and surface texture. Open molds were the first as even an accidental or unintentional realization (finding the metal underneath the bed of coals in the fire pit had filled whatever the sand surface had been including any indentations made by the other sticks of the original fire having burned away and left their impressed cavities). Using the sand / clay mix to make open molds with intentional symbols and then carry or use then as ornamentation came next.
Can you begin to imagine being there then...
and being the rare possessor of a small copper symbol of man or leaf or bird, etc....
and having it polished beyond all other natural materials one normally was familiar with...
and also having it be soooooo strong in actual structure that it rivaled stone.... Gosh and begolly we were be so proud.
This surface indentation and marking then also became natural to add to an enclosed shape sand mold after it had been formed via compacting around a vessel shape body. The positive body was
then removed and leaves and grass placed in the hole to define the thickness of the later vessel.
More sand / clay (we now call this mixture 'green sand') sifted over and into the lesser sized center and re pressed in the hollow or core section of the mold.
Removing the core,
removing the leaves and grass
(HEY LOOK the grass left all these lines, I bet if I drew more with animal shapes or, better yet the figures of the men at the last hoedown where we chewed those nuts that got us all goofy. Man, gums are still black. Wow that was some... I wonder when I got this tatoo... and the fires were so
pretty and I remember while looking at the flames I finally realized... now that was deep... can't remember what I realized but it was really deep, I remember that.) (Oh yah, if I put or press more shapes or lines or remove parts of the mold surface the metal will show this also when we cast it. I'll put the figures of that dance we did. That was some party, this could like a commemorative thing, know what I'm saying?
Anyhow there are two really great books you should look for.
THE BEGINNING OF THE USE OF METALS AND ALLOYS
covers from as far back as can be found in a very complete group of dissertations and research papers compiled from around the world and from many diverse cultures.
edited by Robert Maddin
c 1988 Massachusetts Institute Of Technology
ISBN 0-262-13232-X
check Lindsay Publications for this, they had it once years ago
Bradley IL. 60915 USA
and if you want to see the pictures of a more current period (via engravings and etchings)
A Diderot Pictorial Encycloedia of TRADES AND INDUSTRY covering Manufacturing and the Technical Arts in Plates Selected from "L'Encyclopedie, ou Dictionnaire Raisonne des Sciences, des Arts et des Metiers" of Denis Dederot
Dover Publications of New York has put out a two volume set in soft paperback (not nearly the quality of my older book set, lost in a fire, but still very much worth it). bpfink
ISBN 0-486-27429-2
Diderot's Encyclop�die
The Encyclop�die ou Dictionnaire raisonn� des sciences, des arts et des m�tiers, par une Soci�t� de Gens de lettres was published under the direction of Diderot, with 17 volumes of text and
11 volumes of plates between 1751 and 1772. Containing 72,000 articles written by more than 140 contributors, the Encyclop�die was a massive reference work for the arts and sciences, as well as a machine de guerre which served to propagate Enlightened ideas.
bpfink
bpfink@artmetal.com
http://www.fink.com/bpfink
http://www.artmetal.com/village/chat/main/transcrp/980129MN.htm
PS:
ARTFL has released a prototype of volume 1 which outlines "many of the approaches and functions they see as being vital to the development of a hyper-media edition of a scholarly resource".
http://tuna.uchicago.edu/homes/mark/talks/NWU96.html
http://tuna.uchicago.edu/homes/mark/ENC_DEMO/
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