Spelter Details ?

I known it's a zinc alloy heavily used from about 1880 on, but what are the variations of the metal composition found in terms of quality. Some pieces, like the ca. 1910 lamp I just bought are of nice quality & weight (my recent thread in the 'antiques' forum). While other items are light and fragile, just downright cheap in every way. Is there a source of info on spelter in regards to the 1880-1930 era ?

 

There's a reason why the generic name "pot metal" applies to what we also call "spelter." No specific formula and thus no 2 items will have the same weight. The casting skills of the maker (and the quality - in terms of detail in the mold) will also make a difference in how articles made of spelter will look.

 

I wonder if the differences you are seeing aren’t simply due to the differences in casting process/molds, etc used by the maker, as opposed to differences in the alloy? I’m thinking spelter used to cast decorative objects is primarily zinc and the specific gravity (the property responsible for the weight of a given volume) wouldnt vary much from one object to another.

 

I figured there would be manufacturing standards and expectations for meeting a given quality. . . a given casting formula - varying percentages of types of metals like what is seen with other metals where there is a difference in the amount of nickle, lead, ect. that is added. Guess it comes down to the metallurgy of who ever is doing the casting - little is written on spelter, but volumes on steel & brass & pewter . Maybe it is the quality of the casting, but I do sense metal differences in the spelter objects I own...then again, it could be my imagination.

 

Hi Drew,
There are so many variables to spelter. I have pieces that are so soft you can dent them with a fingernail and some that are so hard you need a hammer to dent them.
Some have a high zinc content some have a high lead content. There is no standard formula for it. Since it is a cheap alloy it is whatever is used at the moment. I do not think there is any formula or standard.
greg

 

I don’t know the first thing about this, but I found this :

https://books.google.com/books?id=K...oECAAQAQ#v=onepage&q=spelter standards&f=true

 

Here’s the standard for commercial zinc aka spelter on pp. 1310. I noted that there were 5 grades of spelter identified, the most impure of which contains well under 2% of both commonly-found contaminants. So if you bought anything a metals dealer was allowed to call either zinc or spelter, it was at least 98% pure zinc metal.

I don’t know if manufacturers of decorative objects then melted it and added anything else or not. I have reason to doubt they did because additives may cause problems in the casting process, I’d think they’d only be considered if there was a significant cost savings or a necessary performance improvement.

https://books.google.com/books?id=4...AE#v=onepage&q=spelter metal analysis&f=false

 

Sniped by The Hunter!

 

Not really SNIPED, you have a basic understanding of this, I do not!

 

Hi,
There are so many names for this stuff, white metal, casting metal, zinc oxide and others. Spelter is commonly called for all of these. Like Kleenex is used for all nasal tissues. I still call the refrigerator an ice box. I think most people just use spelter even for different stuff.
greg

 

Very informative - Borough of Standards listing of five grades of spelter. Like almost all high volume manufacturing, quality control is vital. Thanks for finding this reference.