Sciencemadness Discussion Board

metalsmith

Magpie - 9-9-2010 at 15:27

Quote: Originally posted by metalresearcher  
I recently moved to a new home in which I dedicated one room as my silversmithing room and lab including a fumehood.


Metalresearcher, I was wondering if you do any metal casting using the lost wax process. Specifically, I'm wanting to learn how to cast a silver or brass retort (RBF), about 100mL capacity, 2-3mm wall thickness.

Mr. Wizard - 9-9-2010 at 18:11

A silver flask would be an ideal electro forming project plated onto a low melting alloy or a form coated with graphite, aluminum foil, or spray galvanizing paint.

BromicAcid - 9-9-2010 at 18:49

At one time I was looking into the lost wax process specifically for making a silver retort (for hydrazine) however I found that without a significant investment of time (and to some extent equipment) I wouldn't have been able to get good enough to perform the feat I so wanted so I looked into electroforming. Check out this thread:

http://www.sciencemadness.org/talk/viewthread.php?tid=1990

I don't see any comments from you in it so it may be new for you. Sadly enough even after learning about electroforming it didn't seem that much easier. Developing an even coating can be difficult as can electroforming a coating thick enough to work with. Best of luck with this one :D

Magpie - 9-9-2010 at 20:53

Quote: Originally posted by BromicAcid  
At one time I was looking into the lost wax process specifically for making a silver retort (for hydrazine) however I found that without a significant investment of time (and to some extent equipment) I wouldn't have been able to get good enough to perform the feat...


This is the same purpose and conclusions I have. ;) Between Vogel and OrgSyn, silver or copper can be used.

When I read the hydrazine procedure I did not see why I couldn't use glass so I gave it a try with a 100mL RBF. The problem is not corrosion but terrible heat transfer that is caused by solids that settle on the bottom of the retort. I terminated the distillation early as I was afraid I would crack the RBF. Consequently my hydrazine was only 3% vs the design value of ~25%.

I only recently wanted to make the hydrazine so don't even recall the thread you indicated. Maybe it was before my time. Reading though it further confirms my prejudices about electroplating/electroforming. I just have no experience in that area.

metalresearcher - 10-9-2010 at 00:27

Quote: Originally posted by Magpie  

Metalresearcher, I was wondering if you do any metal casting using the lost wax process. Specifically, I'm wanting to learn how to cast a silver or brass retort (RBF), about 100mL capacity, 2-3mm wall thickness.


I did this years ago I still have the cristobalite investment now I do more sand casting and casting blanks for making wire and sheet. But I'll do lost wax later on.

metalresearcher - 10-9-2010 at 01:49

Thai I 'll do the lost wax casting in the near future .... I still have the equipment.

Wizzard - 10-9-2010 at 04:53

It'd be easier to vacuum deposit zinc onto whatever you'd want to plate- Zinc is gaseous and will adhere at 900*C in a low vacuum.

Magpie - 10-9-2010 at 08:11

Quote: Originally posted by metalresearcher  
Thai I 'll do the lost wax casting in the near future .... I still have the equipment.


When I looked into this it seems like a centrifugal caster and possibly a vacuum bell jar would be required. I already have a muffle furnace capable of melting silver, and I have found a brass that I could likely also melt.

Used centrifugal casters for dentistry are available on eBay, but they are a bit expensive. There are many for sale so a person might get lucky and get one cheap.

What equipment do you use for this process? Do you think casting a 100mL round bottom flask (RBF) would be quite a challenge?

watson.fawkes - 10-9-2010 at 09:03

Quote: Originally posted by Magpie  
What equipment do you use for this process? Do you think casting a 100mL round bottom flask (RBF) would be quite a challenge?
I might mention that many art foundries will happily take on contract work, if you're more interested in acquisition than making it yourself. If you can provide them a wax positive, they don't have to charge you for the labor of making one.

Fleaker - 14-9-2010 at 15:24

I do lost wax casting. I have some Kerr-satin cast that I no longer use if you'd like it; just pay shipping. It is still good. I also have some molding wax, beeswax, paraffin, and some fillers too sitting around somewhere.

I also have silver too :-)

Magpie - 14-9-2010 at 15:38

Hello Fleaker. What is your opinion of my proposed casting of a silver or brass 100mL RBF? Do you think it would be tough to do?
Would you prepare a solid sphere negative of investment first, then coat the inside of this with 2-3mm of wax, then pour a solid sphere of investment inside the wax shell? Or what? Just how would you do this?

quicksilver - 23-9-2010 at 13:49

One of the FINEST jewelery makers I ever knew started as a teenager & was a close friend. His whole life was different aspects of jewelery making and he used lost-wax like no one I had ever seen or have seen accomplish better.

He had a little "H" shaped pivot for his molten metal and used it to "time" the pouring of metal which he insisted was his "secret" to getting such ultra fine casts. The "H" shaped platform kept his timing of pour to a certain level as also his lack of "giggle" or hesitancy. The item was home-made and simply consisted of a stand such as a "goal post" which he could insert a ladle of molten metal (he used both silver & gold).

I have NEVER seen such items duplicated as he did. And he was very free with his knowledge. He once said that very fine professional wax had different "speed grades" of pour with differing metals and that certain suppliers had that information whereas others never even heard of that issue.

He once did a series of bronze castings in the "old style" of bronze age casting in which he made arrow heads, spear heads, a knife, & a sword. He then found a collection of aging chemicals which put such a deep crust of patina on them that it was honestly difficult to believe they were manufactured a week ago.
I do know that he once said that he thought about writing a book and I hesitate to write his name in public but if I ever DO find that he wrote one I will post it as I really believe he was as gifted a man a I had known in that art. I knew him from when we were about 13 to out late 20's & he was mostly self taught!