Sunday 4 August 2013

New Powdered Silver Clay

Some time ago I came across a powdered silver clay that I had not heard of before, made by an American company that specialises in manufacturing powdered silver and silver nitrate to laboratory standards. I arranged to be sent a 10g sample and have finally got round to testing it.

Simply called 'Metal Clay Powder Silver 999', a 10g pack contains 10g of silver plus 0.5g of binder, so the weight stated on the pack is the actual weight of pure silver you get. When mixed with water, a 10g pack gave me 11.8g of clay.

Unlike other powdered metal clays the silver and the binder are packaged separately, which is probably due to it being more convenient (and more accurate) for the manufacturer to do it this way. It is a simple matter to snip the corners off the packet and mix the silver and the binder evenly before adding water. The included mixing instuctions specify kneading for 4-5 minutes, but I followed my normal mix-and-roll-out method that I use for base metal clays and when reconstituting silver. This clay does need a 15 minute rest time before use as well.

In handling it felt more like ACS Slow Dry than other silver clays, and was very smooth. It took texture well from a burger box texture plate, picked up fine detail from a mould and rolled out to a nice smooth surface, even though I rolled, shaped and reworked it several times because I couldn't make up my mind what to make.

In the end I made three pairs of earrings and two pendants from the 10g pack. It was easy to make paste both from lump clay and sandings; drilling didn't cause chipping and the dried clay cut cleanly with a scalpel blade when I was trimming the edges of the shell mould. I didn't need to do much in the way of sanding before firing, and everything polished up quickly and easily, including those parts where I wanted a mirror finish.

Firing can be done between 677 deg C (1250 deg F) and 900 deg C (1650 deg F), with similar hold times to other silver clays. As my pieces included sterling silver earposts I fired them at 780 deg C (1436 deg F) for 40 minutes - less time would have done but I always fire for longer than needed.

The stated shrinkage is 12-25%, with maximum shrinkage occurring at the top end of the temperature range and with longer hold times. As all silver clays exhibit higher shrinkage at higher temperatures I expected this, but if shrinkage is 25% at 900 deg C then it holds out the possibility of a replacement for PMC Standard which many of us sorely miss.

I really like this clay for its handling, joining characteristics and plasticity. But maybe the best thing about this silver clay is the price; at the time of writing a 50g pack is $79.99; shipping is free in the US, and international shipping is $18.00. Which means I can get 50g of silver (approximately 60g of made-up clay) for about £66.00 (€76.00) which is way less than any other silver clay on the market.

The only drawback is that this silver clay only comes in 50g packs but it has an almost indefinite shelf life until it is mixed with water so it is very economical.

There's more about this product at http://www.metalclaypowder.com/ and it can be purchased from http://www.silvernitrate.org/ or http://metalclayalchemist.com/produits.php?cat=183 (Canada).

3 comments:

  1. Hi Pat
    Did you get that high shrinkage at the higher/longer temps? I'd like to know as will miss PMC Original for its shrinkage & workability. Thanks Lisa

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  2. Thanks for sharing! Apart from this powder metal parts are also very useful and interesting to use!

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  3. This is great!

    Can I fire this with a torch or do I need access to a kiln? I have no space and less budget for a kiln. :P

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