Saturday, December 31, 2011

Pewter brooch

  Last night when I was working with Mistress Bengta and creating my (still perma-smile over this) glass beads, we had some down time while the beads were cooling. She asked me if I had ever worked with pewter or casting? Nope. Wanna try it? Sure. When I got home last night (much later than anticipated) I came bearing gifts to my husband of pewter with the beads.
    In the article "Pewter Casting in Stone Molds" written by Darrel Markewitz in 2000, I learned much about the history of casting. He states; "If gold was the material of high kings, sliver for the wealthy, and bronze for the 'middle class' - it remained for pewter to fill the need for the simplest of ornaments. Pewter, an alloy of lead and tin, mimics the appearance of silver - at least when freshly cast. Not a large number of pewter artifacts remain from the Viking Age, if for no other reason that the material will quickly oxidize and decompose. What samples that have been uncovered are of the simplest workmanship." This tells me that a simple pattern in the cast would have been normal in this time. Pewter was very common, easy to work with and to obtain. Darrel goes on to state in his article; "More clues to the use of pewter by the Norse can be seen the uncovering of many moulds suitable for producing objects cast in this material. Pewter has a relatively low melting point, in the range of 750 F, which is easily attained in a small fire with no special equipment or fire modifications. With a high lead content, the molten metal is fairly fluid, allowing for the use of open topped moulds, such as the antler sample found at Hedeby for a simple disk broach. More complex shapes can be produced through the use of carved stone moulds, such as the dragon mount mould found at Birka. In this case the carved block of soft slate or soapstone would be used in conjunction with a flat backing plate and poured from the edge." The only real limitation I see according to this article would be the time available to you to make your molds. As I found out, making of the mold is very time consuming.
    I began by deciding what I wanted to make. The red over tunic that was made for this competition has a wide keyhole. I decided to make a small brooch, simple in design, that would be big enough to attach to the corners of the keyhole without pulling it in and making it pucker. It needed to be simple because there is embroidery and an amber pendant already in that area--I really did not want an over kill. I opted to create a circular brooch, wider at the bottom by the opening, that has a design made from the carving. I did not clear out and make smooth the entire area that would be the pewter--I left three triangles on each side that did not get carved. It made it so I have three triangular "holes" on each side. I like the effect.
   I used Bengta's tools and dug and dug and dug some more to carefully make the mold in the stone. It carved out easier than I was expecting. It was very time consuming--two and one half hours for this simple design and my finger is still numb. When the pattern is carved out and smooth and how you want it, you then make the funnel or channel for the pewter to pour into your mold. I placed it opposite the opening on my mold, on the bottom of this picture.

    We then went and poured the mold and turned it into a brooch. I discovered that the pewter cools much quicker than I expected and one needs to allow the hot liquid to pour fast or you only get half of a mold filled before the pewter is done. That one simply went back into the pot to remelt and try again. Success.

    I am quite pleased with my first attempt at playing with pewter. I can see that I need more practice making the smooth areas smooth, but not too shabby. This will look very nice against the red linen of his tunic. I do believe I will be doing more of this. It was rather satisfying to start with a stone and a knife and end up a few hours later with a servicable pewter brooch.

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