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  #1  
Old 11-23-2005, 07:11 AM
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clifton clifton is offline
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hand casting pewter

I am thinking of trying some things in pewter
but hand casting into rtv silicone molds didn't work out so well
there seems to be off gasing, which diffuses some of the detail

I see that it is possible to buy a pewter formula from the UK
that is advertised as suited to hand casting in rtv
but I don't want to order from overseas

it could be the low cost rtv silicone I am using
but I see it mentioned as a problem in a few places on the net

I am thinking of trying a mix of plaster and sand
and cast into that
either making a positive mold
or a wax copy to be burned out

I don't care for carving negative molds in soap stone

I wondered if any on here are hand casting pewter
and if there are any suggestions on using it

appreciate any comments,
Clifton
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  #2  
Old 11-24-2005, 02:10 AM
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Landseer Landseer is offline
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Re: hand casting pewter

I've used Woods metal in latex rubber molds before (Bizmuth/tin/lead/cadmium alloy melts around 175F,) same gassing problem leaving a rough surface. I solved the problem by amazingly enough coming up with the idead to apply Kester's soldering paste to the inside surface of the rubber mold. The idea was the paste is used for soldering and helps the solder flow, cleans it etc.

I don't know if it will work for your higher temperature but it worked for my finely detailed medallions project so I'm thinking at the very least the metal might need something added to it when molten- which is essentially what the soldering paste did since the metal was molten in the mold for a bit and no doubt the paste which melted into it did something.
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  #3  
Old 11-24-2005, 07:18 AM
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clifton clifton is offline
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Re: hand casting pewter

Hey, thanks Landseer!

Clever idea. Definitely worth a try. Never though of that.

I'll get to it this week end and let you know how it turns out.

Clifton
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  #4  
Old 11-25-2005, 11:35 PM
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Landseer Landseer is offline
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Re: hand casting pewter

While I used the paste, there is a liquid form, but the paste melts right away so it doesn't seem it would matter.

Since you are going higher temperature than I did, I'd be wearing something on the face/covering exposed skin etc in case of sputtering- it could get like splattering grease on a frying pan maybe I don't know.
I didn't apply much to the mold just a thin coating like painting the wall.

Be aware too, since the flux is an acid, it will eventuall degrade the rubber probably, it didn't seem to bother the latex though or shorten it's life.

The paste was the last thing I tried, I tried vibrating the mold, banging it the table, even probing the face of the rubber with a stick to dislodge air bubbles, I tried hotter temps lower, pouring fast pouring slow you name it, nothing seemed to work, THEN I tried the Kester and that DID.

Last edited by Landseer : 11-25-2005 at 11:37 PM.
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  #5  
Old 11-26-2005, 02:20 PM
F.C. White F.C. White is offline
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Re: hand casting pewter

Another simple effort to try would be to coat the mold with aecetlyne soot or just straight propane without any additive air flow. Bullet makers have problems with shot having irregular surfaces due to off gassing but remedy this with the application of the soot. It's cheap and worth a try, anyway.
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  #6  
Old 11-28-2005, 04:55 AM
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clifton clifton is offline
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Re: hand casting pewter

I had chance to play with the pewter and an rtv silicone mold. I had used the mold for other experiments but it was suitable for testing.

The solder paste idea worked, but not if the thickness of the pewter is greater than about 1/8" or so. Some areas, that were about 1/4" thick had some of the gassing affect. There was some loss of detail with the paste, and a bit of a smoothing affect that may even be desirable. Using the liquid form may help as could carving the details a little deeper in the original.

I didn't try the soot, but I will.

I think some of the problem is related to the metal being too hot for the rtv silicone. Hence the thincker metal causing a problem. I had been dripping the metal slowly on to the rtv, and that worked, but it cooled too much, and did not always form a strong bond to previous metal. I thought it would be a simple way to cast in 3d.

Seems like I may have to invest in lower temperature pewter, if I want to cast in rtv molds. Since I need to buy it in bulk, I think I would like to try casting in a plaster/sand mix and try something thin, where I use a two-sided silicone mold. Thin would not be a disadvantage, as it uses less metal, but it might cool the metal too quickly.

I have a lot on my plate, right now, but will be working on the idea in my "spare" moments.

It will be a while before I can build a small smelting furnace and try my hand at a few bronze things. Need to build the workshop first. Pewter seems like it could be an intermediate step.

thanks a lot for the suggestions,
Clifton
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  #7  
Old 11-28-2005, 06:43 PM
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Landseer Landseer is offline
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Re: hand casting pewter

Quote:
Originally Posted by clifton
I had chance to play with the pewter and an rtv silicone mold. I had used the mold for other experiments but it was suitable for testing.

The solder paste idea worked, but not if the thickness of the pewter is greater than about 1/8" or so. Some areas, that were about 1/4" thick had some of the gassing affect. There was some loss of detail with the paste, and a bit of a smoothing affect that may even be desirable. Using the liquid form may help as could carving the details a little deeper in the original.
Don't give up though, I think it took me a couple of tries- vary the amount applied as well as the temperature of the metal when poured. It is possible too that the melt might just be too hot for that rubber.
I had no problems with my dog head portrait medallions and they were thick and the heads of the dogs were very 3 dimentional and solid.

I also cast several solid Brittania alloy and then later when I ran short of that, I added some lead- collie plaques, they were about a pound each into that platinum RTV, and these are at least 1/2" thick solid, and all are very detailed


Quote:
Seems like I may have to invest in lower temperature pewter, if I want to cast in rtv molds.
The only lower temperature stuff I know of contains lead or bismuth, cadmium etc, with these alloys you can get a silver colored metal that melts below 175 I inquired of Fry Metals once way back then and they sent me a 10 POUND ingot of the metal I inquired about as a sample to try- at no charge! It's listed price was somewhere around $14 a pound or so and the alloy was used in the medical field for I forget what, but it was lead, tin, bismuth and cadmium which is not good to play with, but it's melting temperature was around 175 so there were no fumes or burning, and the medallions did not need polishing, chasing sanding, grinding etc- they were simply mounted to a velvet lined framed plaque to hang on the wall, so they wouldn't be handled anyway.

You would never want to use that to make things that are handled like keychains, or sculptures you need to start grinding, sanding or polishing on.

Here's a couple of very old somewhat damaged sample boards, been sitting in the basement for years, these medallion samples are just painted hydrocal but I used the same latex molds as the one shown to cast the "pewter" in with the soldering paste.
Somewhere in the basement I have a bucket full of the metal ones and the collie plaque in lead/tin

Pretty poor pics but the size limit required serious cropping and quality reduction to get them in here, you get the idea of their size and 3D, they are about 1-1/2" diameter, note that almost all the dog's ears and open mouths with tongues presented some fair undercuts, yet they all cast very nicely.

I added a closeup of a metal one, a Boxer dog, the other closeup of the sample board in the background shows how detailed and undercut some of the designs were, the heads were all 3/4 profile, a Doberman, Gt Dane and Papillon can be seen in that photo and you know how the ears on the first two stand up!

The original models were plasticene and I left them with a somewhat sculptured/tooled surface texture, the metal filled the designs perfectly, if anything looks a little pitted or rough to you there, it's not- I had to photoshop sharpen and correct for the florescent lights, so the effect is a little "sharp"

Last edited by Landseer : 11-28-2005 at 07:07 PM.
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  #8  
Old 12-03-2005, 01:49 PM
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Landseer Landseer is offline
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Re: hand casting pewter

I found this little foundry supply outfit the other night;

http://budgetcastingsupply.com/

Looks like they have just about everything one would need to do some metal casting on a small scale. I'm interested in the idea and have 6 finials I need to cast either in aluminum or Brittania alloy, casingt those 6 finials in a two halve plaster/sand mold.
I might look into it in spring, firing up a furnace and casting metal like that is best done outdoors.

The site has a book that I plan to buy;

"Li'l Bertha, A Compact Electric Resistance Shop Furnace" - David J. Gingery; Lindsay Publications, 1984; ISBN 0-917914-16-3

How to build an electric furnace for use in casting aluminum and zinc metals. Practical, low cost approach.
==

They also sell the elements and controllers, one I could go with gas.

Years ago I took a local college's community clay sculpture class in Oregon, the instructor was an adventuresome fellow named Ted Isto, we decided to fire up the gas furnace and try some bronze casting. They had a McEngelvan gas furnace, I forget the specs, but it was about 3 feet high maybe. They had the safety clothes, sheilds, pyrometer, graphite cruciable, tongs etc.

Last edited by Landseer : 02-08-2006 at 10:08 PM.
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  #9  
Old 12-04-2005, 02:05 PM
F.C. White F.C. White is offline
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Re: hand casting pewter

Landseer....... I can help you build what you need far cheaper than what is offered on the market. And "cheap" doesn't mean compromise on quality or safety. It'll outlast anything out there in comarrison, as well. Propane is a great fuel source for any non ferrous metal. It's primary exhaust is H2O and can safely be used indoors without concern of monoxide posioning. I've worked indoors for over 20 years using propane fired furnaces. I can instruct you how to build a furnace that is lightwight, economical and durable enough to pass on to another generation, yet still be easily moved about and stored in the event space is an issue. I've been working on a tutorial in such regard for the past year that would be very beneficial to you if you choose to explore doing your own castings from now on. I'm just an email away if you're interested.
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  #10  
Old 12-05-2005, 06:09 AM
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clifton clifton is offline
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Re: hand casting pewter

thanks for the extra info, Landseer.

I am planning to recarve a fisherman's ghost
a work I had done previously for pewter
I want to have the fisherman embedded in a breaking wave with rope and buoys
I'll take a bit more time on this one
make it larger
and try a three dimensional mold in RTV

Hi FC White,

I have been looking at plans for furnaces as well
propane does seem like the best alternative
the book I have ( "Methods for Modern Sculptors", Young & Fennel, older edition) shows such a furnace
but doesn't give a lot of detail on the burner set up
seems to be just a copper tube inside a steel pipe
I have seen a few designs on the net
but they used oil burners or didn't show the propane burner set up

I would appreciate the info on your design
I'll get an email off to you
thanks for the offer

Clifton
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  #11  
Old 12-09-2005, 09:36 PM
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Landseer Landseer is offline
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Re: hand casting pewter

Thank you FC, I will get back to you on this, right now things are up in the air at work, or at least I perceive it that way after they let one of the engineers go and cut back our hours from 45 to 40 a week till at least spring.

The expected bonus as we had gotten these last few years Thanksgiving week, which I was going to use to pay my credit card off is not there this year

So the hours loss is a good $100 a week hit and going into winter too. I might have to live off my art soon if something happens, so right now THE goal is pay off my credit card in full in 2 weeks and stash away all the cash I can hang onto till spring at least, so that will mean totally stripping down buying materials, extra boxes, packing foam or anything else I don't absolutely need at the moment.
At least I don't have a mortgage but not sure how much consolation that is when there are zero jobs here and my car has 308K on it so it's not likely going to hold up much longer, least of all daily driving to another town.
I had these two bookmarks that offer some burner designs etc


http://www.backyardmetalcasting.com/bucketfurnace1.html
http://www.backyardmetalcasting.com/oliverburner1.html
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