flux when melting pewter?
Posted 03 August 2009 - 07:42 PM
I've been trying to do some home pewter casting but I'm still a long way from perfecting it. It seems like every time I skim the dross from the surface of the molten metal a new skin of off-colour non-shiney metal forms. I keep trying to scrape it all back but I think some is getting into the pour as I'm getting deeply pitted dirty areas on the surface of my cast objects.
I've been trying to think how else I could do it and came up with a couple of ideas.
I've been around people casting silver and they always add a powdered flux to the crucible as they melt the silver. In all the instructions I've found online for casting pewter I've seen nothing to say you need to use a flux. Now I'm beginning to wonder.... are you supposed to use a flux with pewter?
Also, I'm thinking of trying to get a lead melting pot as sold by gun shops that pours from the bottom of the pot so the dross stays in the pot when you fill your ladle.
Just wondering if anyone who's more experienced can tell me if I'm on the right track with these ideas or if there's something simple that I'm doing wrong at the moment. Thanks.
Posted 04 August 2009 - 04:07 AM
Short answer is no, there is no need to.
add a powdered flux to the crucible as they melt
You will never get ahead of it, as it is a form of oxidation.
I skim the dross from the surface of the molten metal a new skin of off-colour non-shiney metal forms
Problem it will form as you fill the ladle
get a lead melting pot as sold by gun shops that pours from the bottom of the pot so the dross stays in the pot when you fill your ladle.
You can make a divider for your ladle that has slots in the lower part so as you pour the dross stays behind on one side. A piece of sheet copper, cut to conform to the bottom of the melting container. At this time I can't seem to find mine. I generally make a new one each time as I can never seem to find them. they are held in place by bending ears from the sheet metal over the sides of the ladle.
Since the temp of pewter melts at 450' to 500' F depending on the alloy.
You can use a soft pine shim or other piece of wood to skim the dross off.
when the pine starts to char it is ready to pour.
You can collect and return the dross to the melting process if you are dealing with quantities. Also after it is cooled in the ladle you can tap it out on a brick and dispose of.
One note of caution, as the airborne dross particles can be toxic.
No its just the way it is, and the articles that are cast will develop the oxide skin after casting. One of them can't mess with mom nature moments.
something simple that I'm doing wrong at the moment.....
Here are a couple of the better books on pewter casting.
Tim McCreight's pratical casting
Jay D Kain's Cast pewter jewelry
The second is a long time library standard on jewelry and casting
"I am not ashamed to admit, that I am ignorant of the things I do not know"!
I am not a lawyer, and never played one on TV!
All the usual and standard disclaimers apply. Do not try this at home, use only as directed, No warranties express or implied, for the intended use or suggested uses, Wear safety glasses, closed course, professionals only
Posted 04 August 2009 - 08:32 AM
Posted 04 August 2009 - 10:44 AM
Posted 04 August 2009 - 12:41 PM
has lots of possibilities. http://www.hooverand...og/archives/11/
Chill can happen most commonly with cold metal molds, or cold invested flasks. Flask temperature is one of the variables. Pewter is usually cast into vulcanised rubber molds. Venting becomes a greater issue than metal temp or chill. Pewter is a very different metal from golds, silvers, brasses and bronzes. The obvious difference is one of melting temp. The other difference is that pewter will not flow as thin as far as the others. In other words the detail possible with the others is much greater, actually in descending order as I've listed them. Models made to be cast in gold could be cast in the others but not cast in pewter. The other thing to consider is the tensile strength and durability of the metals. Pewter is not very strong. Therefore cast pewter items are much thicker than castings made in the four dominate materials. This gets into considering the use of the finished item. Pewter handles may work fine, while pewter forks might not be such a good idea. Just some thoughts. Brad
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