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Outdoor pewter
Michael Reddell -
Saturday, January 15, 2011 - 4:18pm
Casting Are there any issues with pewter outdoors? I am using a tin/bismuth alloy. I'm guessing that the oxidation issues are more along the lines of patina rather than corrosion. These pieces will be outdoors in weather on the California coast with salt air. Iron alloys are catastrophic in this environment, aluminum tends to corrode with a white powder. Bronze & brass are excellent, with natural patinias tending toward green but I don't have any experience with pewter. I expect a dull gray patina and not much else. Also, does anyone have experience with patinas on pewter other than the natural gray? I have some ferric and cupric nitrate and ammonium sulfide for bronze. Has anyone tried these on pewter?  Pewter gray is ok, I was
Michael Reddell -
Sunday, January 16, 2011 - 10:28pm
Pewter gray is ok, I was just wondering. It is small scale figurative work for the garden. Think of tinkerbell. I'm experimenting with direct casting from high temp silicone rubber molds. Thanks for the input. pewter patina
Michael Reddell -
Monday, January 31, 2011 - 2:07pm
So far, the only patina agent I have found (very limited research thus far) that reacts with pewter is cupric nitrate. Cupric nitrate turns bronze green, but it darkens and dulls pewter without changing the color. To this point I have found nothing that changes the color from pewter grey to anything else. I am using cupric nitrate in a very weak solution to take the new shine off of the pewter and give it an aged appearance. Too much CN makes the pewter dull and lifeless. The only other thing I have tried so far is ammonium sulfide, which does nothing at all.  Pewter Patinas
johndach -
Monday, January 31, 2011 - 3:19pm
We have done small figurative (animal) work in direct pour and also invested casting. We bought our Pewter from ROTO METAL in San Francisco (they have many alloys , we used Tin/Antimony). We were after a black (in the recesses only) patina and found that some of the spray graphite "lock lubricants" worked great and could consistently be applied and wiped back to what ever degree one needed/wanted/was looking for. I know it is not a "true patina" but it did give a very nice contrast for the very fine detail in the pieces (North American at Risk Wildlife figures/miniatures). I think that a sal ammoniac solution (not sure if this is the correct chemistry) can be used as a darkening patina but it was dull and variable, not something we were after on these small, detailed pieces. One reason tin was used for food, is it was non reactive so trying to get a chemical reaction is exactly what true pewter was used to NOT do. Good luck in your search. If I come across the actual patina info (somewhere on one of the old drives) I will post it. John Dach good comments, John. I have
Michael Reddell -
Tuesday, February 1, 2011 - 12:43pm
good comments, John. One thing I have wondered about is whether a higher copper content might make it a bit more reactive. The alloy I am using now is 98% tin, 1.5% bismuth (for shrinkage control) and 0.5% copper. There are alloys with significantly more copper. Michael Pewter Patina
johndach -
Tuesday, February 1, 2011 - 2:39pm
"True Pewter" (VERY high tin content) verses what other alloys of tin are made up of and called "pewter" are a problem in the figurine industry. The near pure tin alloys, the true Pewter material, are/were made as such so that they were food safe and "non toxic". Other metals were added to gain different characteristics but true pewter, to my understanding was nearly 100% tin. Soft, non toxic and food safe. Today we have high lead content alloys (mostly from China but also from other countries of the world) as lead is MUCH cheaper than tin yet has many of the same qualities of tin in looks (color, grayer not as bright as tin), ease of melting (low temperature), flexibility, relatively non reactive, etc. But a high content lead (or other alloy(s)/tin) tin mix is not in my books "Pewter",,,,, it is an alloy with tin in it. Lead has been used for food/water use in the past and has caused the fall of empires (or at least it has been felt a cause). I know "pewter" has a great selling name, but anything very far removed from near 100% tin, in my thinking, should not be called "pewter", ESPECIALLY it the item is a food use item or a "toy" to be handled a lot. As to the alloy with copper in it, I "think" that the amount of copper would not be high enough to get a reactive surface for chemical coloration. If you feel so inclined, I would highly recommend giving ROTO METALS in San Francisco a call and see if they have any thoughts on outdoor/patinatable alloys. Also higher copper content alloys may very well have problems being/getting melted as there is nearly 1000 degrees difference in the melting temperatures of copper and pewter. Good luck on your searches.............. John Dach |
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ArtMetal
None that I'm aware of, I'm
None that I'm aware of, I'm about 70 miles from the gulf of mexico and have had some outside for 2 years and its not really showing that much patina. What I've got is tin/ antimony/copper though.
I can not remember exactly what all I've tried in the way of patinas ,but, it was about everything in Sculpt Nouveaus sample box (maby 50 diff. patinas) and hardly 10 percent of them worked, mostly the stuff with die in it.
What are you doing with it? I love the stuff but its so expensive.
KevinW