Friday, October 15, 2010

Count Down Fun! 5! Part 2, "You know . . ."

[I just discovered that this was saved as a draft last night when I fell asleep in my office chair!  So here's yesterday's second post ~ please just ignore any confusing tense usages and pretend that you're reading it yesterday  .  .  . ]

You know, there's a reason that casting is as much an art form as it is a science . . .

Pat test wearing our newest
Seasonal Botanicals in Sterling Silver !!!

This is another case of taking a break outside and really looking at the wonderful world around us.  I saw this amazing shape and knew that I just had to see what they would look like, and feel like, what they would be as a piece of jewelry.  How could anyone possibly improve on this form, this shape, these proportions???  You can't.

This is one of the first pairs of earrings that I had to try to cast (I think it was) last week (?) because of this inspiration.  (The days are beginning to blend together a little!)  And yes, if you saw my last post, these are actually seed pods from our Ipomoea guamoclit, or Hummingbird Vine.  These beautiful earrings began life as this beautiful flower:

Hummingbird Vine, also known as Star Glory or Cyprus Vine,
Ipomoea guamoclit.

Talk about a stretch your limits challenge!  The first test casting went well and I learned a number of things.  There was no way I could stop with just a couple.  So I had to make more!  But the clock is steadily ticking away and I just don't have time for experimenting ~ if something doesn't work the time and energy and effort is gone.  (But not wasted!  Sometime we have to learn certain lessons more than once . . .)

It was disappointing to take Tuesday night's castings out of the ultrasound and think I'd found shrinkage porosity last night.  I used a miniature cut off disc to desprue the castings today.  And I feel alot better.  Only a couple actually suffered from shrinkage porosity!  (Generally caused by too small a sprue supplying too little metal to too large a mass.  Which was exactly what happened here.)  The rest are perfect and we'll have them at the Guild Fair!  (Providing we find the time to get them all finished!)  I got them all de-sprued and rough ground for Pat today.  She finished up the forged rings so I've got them waiting in the que for grinding and buffing and final polishing.

Between our long dry spell and the cold nights we're having now these might just be the only Hummingbird Vine castings I can make this year.

Our chains haven't arrived from Italy yet, so I called today.  They should be here today or tomorrow.  As long as we have them by next Wednesday we'll be happy.

While I was minding the kiln today Pat got lots more finished up than I did.  Thank goodness!  (Why, oh why, do I still think I can get a dozen other things done when I'm casting???)

Ferns, waxed and ready for spruing*.

So I made dinner a little later than I probably should have tonight.  Pat offered to, but I was already so hungry-wired that I just wasn't being effective so it was better for me to stop working and get into the kitchen.  I made Pat flop on the couch with a good book.

So we ate and then I cast the Ferns at 7:27 tonight.  It was 56 degrees out, though because the kiln and Electro-Melt were running it was 65 in my casting area.  I charged the Electro-Melt with 59 grams (just a smidge under 2 ounces) of Everdur Silicon Bronze once it was preheated to 1850 degrees Fahrenheit.  The kiln and flask were at 950 degrees F.  Normally I'd cast Silicon Bronze with the flask at 900, but it was a cool evening and the ferns are delicate finely detailed pieces.  (Remember that:  "Delicate finely detailed pieces" . . .)

Here's tonight's 1 minute 30 second video of the pour.  If you want to skip ahead to see the four seconds it takes to pour 2 ounces of molten metal, the Fun Part starts at 54 seconds.  This is the make or break point of more than two very full very long days of work and another day spent burning out the flask . . .
 video

Ten minutes later, because it was so cool, the button wasn't glowing and it was time to quench.  And I immediately knew I had problems.  Despite the extremely excessive spruing three of the five ferns completely failed to cast . . .

Gut-dropping, stomped flat, sick to the stomach about sums up how I felt when I first held the castings in my hand.  What ???  Sure, we all know ferns are too thin and too light to cast.  But I've done 'em before and . . .

When I first started casting [lets be polite and just say it was a couple of decades ago, okay?] everything that could go wrong did.  There are so many things that have to be just right to making a casting work, or not, that sometimes I couldn't figure out what had happened!  I wish I could find it now but, I wrote out a list of every single step involved and what might go wrong if you made a mistake at any step and what the affects would be on the casting.  For some reason the number 311 still jumps into my mind all these years later.  (It might've been 315.)

So by my, ancient, calculations from the wax stage to the final quench there are more than 300 hundred ways that you can completely mess up a casting . . .

But more importantly, just what the heck went wrong this time?!?  And how the heck have I messed up two castings in a row???  Am I really that tired???

The metal temp was at 1950 when I poured.  Silicon Bronze is, like DeOxidized Sterling Silver, kind of funny stuff to melt.  There's the melting point of the metal and then there's the liquidous point ~ and sometimes there's another altogether different temperature for the pouring point.  When Silicon Bronze first melts it looks like an antique mirror with a crackly crazzed surface; raise the temperature another 20 or 25 degrees and that affect disappears as the silicon is activated and you're good to pour.

Okay.  It looked good or I wouldn't've poured when I did.  But my first suspicion was the metal's temperature and even though I tried to allow for the ambient temperature that's where I looked first . . . 

Oh.

Here's what I forgot to allow for!!!  Yep, I poured at the correct temperature ~ for a dense heavy casting.  For light delicate ferns I should have poured when the Bronze was another 50 to 100 degrees higher!!!

There's nothing to do but make a note in my casting log and hope that I'll always remember to double-check in the future.  Then you turn the music on and smile and dance.

It's such a Beautiful World and there is always more to remember and to learn. 

So if that was the problem why did I say casting is as much an Art as it is a Science???

Because if I had listened to, and really heard, my own inner voice saying, "Um, it's not hot enough yet . . ." regardless of what the pyrometer said, I think they would have all turned out perfectly.

I didn't listen.  Now all I can do is dance and smile and laugh with the music.

If today is suddenly Friday it must be time for lists, or maybe it's time for bed   .   .   .

Sam & Ink again, late this July, just because.

*Gee, aother word that I seem to automatically misspell!  Sprueing should be spruing.  Though ti, er, it makes me feel better to see how many people have googled sprueing and landed on our blog!

Count Down ~ For Terry!

Inky sez:
Feel better Terry!

Sammy sez:
You better listen to him or I'll call Niles!

Mom & Dad Wanna Send You Some Flowers

Dad, we said Flowers!


Tha Boyz are worried about you too Dearest Sister!