Siver Cobalt recipe with SP 87

[Dave Bross]

Some other thought on how to streamline this process:

We don't really know what the actual expansion of the SP color base is because it's

missing the antimony and nitrates. The actual expansion will be slightly to extremely

different in different furnaces anyway, so actual melting and testing is going to be the

fastest route to a usable result.


Personally, I would want a baseline number for just the color base batch in that particular melter, so I would mix it

up and melt it without any additions and check what I get for expansion. That's not the

quickest way if you just want one particular color though, it's more about investing time

and money to have a baseline number for all future color experiments so I would know

which way and how far the color additives were moving the expansion.

Here's how I check expansion:

http://talk.craftweb.com/showpost.ph...&postcount=100


If I was in a hurry (rarely happens) I would add the coloring materials only to the batch,

tracking them by percentage. I would melt it and check the expansion on that. I would

adjust the second melt to attempt to get the expansion spot on. I say do the expansion

correction before any color corrections so you will at least have a good chance to get

some glass that's usable compatibility-wise even if it's not the color or effect you were

after. From there I would tinker with getting the color/effect the way I wanted it.



Unless you get very lucky, you're usually looking at a minimum of three melts to begin to

get something usable. Another good argument for doing small melts to experiment.

Usually, the more I hurry the longer it ends up taking.

More reading on this subject:

http://talk.craftweb.com/showthread.php?t=7232

[Jon Myers]

and hitting it after 3 melts would be doing good

[Randy Kaltenbach]

Inquiring minds need to know, Brice. Did you manage to hit it yet?

[Rollin Karg]

Originally Posted by Randy Kaltenbach

Inquiring minds need to know, Brice. Did you manage to hit it yet?

Dang !!! Talk about getting personal

[Brice Turnbull]

Yeah, really Randy - she just moved here a week ago. Isn't there a 'grace' period when you're supposed to be nice?

-----------

I've thrown out the other 82 pounds of my SP color base, since I didn't mix the whole 100 pound bag before scooping it into the furnace

I'm going to use a recipe closer to my original proposal, with SP 87 w/erbium and see where I get.

The recipe I used in the past with 87 w/ erbium worked the first time, second time, and third time.... with I hadn't lost it...

[Pete VanderLaan]

You can use regular SP just fine. It will take more black tin to try to overpower the nitrates. It may well take extra silver as well. You had a lot of silver in that formula though already.

[Brice Turnbull]

Thanks Pete, I'll keep that in mind when I re-write this little recipe.
Cheers,
Brice

[Brice Turnbull]

Alright, no more color base for me, so I'm planning a melt tomorrow with this recipe, which is closer to my old recipe (I think) that worked each time I melted it the first time out of the gate, except that I'm adding the boric acid and lithium to bring out the silver and make it less viscous at work temperature.

When it's melted, I'll gather it out, and pull some thin rod with clear to see if it bends, and encase some in a paperweight and see if it fractures, and blow some in the center of a vessel which I will then drill in a couple of places to see if it checks.
I don't know about the ring seal test, so I won't plan to do that.

25 pounds of SP 87 with erbium

a pinch of Black Copper Oxide (less than a teaspoon)
.8 ounces of Black Cobalt Oxide ( .23% by weight)
.3 ounces of Black Tin ( .08% by weight)
a pinch of Red Iron Oxide (less than a teaspoon)
.8 ounce of Silver Nitrate ( .23% by weight) = .54% total

2 ounces of Boric Acid (.4% by weight)
.7 ounces of Lithium Carbonate ( .13% by weight) = .53% total

I'll check back here to see if anyone has shot me a warning missile, but I'm pretty well planning on using this recipe.
I'll post how it turns out,
Cheers,
Brice

[Pete VanderLaan]

Just make a cylindrical cup putting the color on the inside and the clear on the outside. Cut off a ring with a diamond saw. In reality if it cuts the ring without breaking, it's compatible. Try that with most German rod. If it cuts the ring, write back and I'll give you the next step towards Nirvana.

In all of my classes I caution against never doing more than one thing to a batch at a time.

[Dave Bross]

I second what Pete said. Rule #1 for any test and tune project in anything is to only change one thing at a time.

I would not do the lithium or Borax unless you had to for some definite reason. SP is already nearly 1% lithium and that is a lot. You'll be getting into the zone where it can eat your pot adding more. Even that tiny amount of lithium will move the expansion a lot.

I would want a baseline first melt to see how far the color additives threw the expansion of the SP all by itself...then I would tinker with viscosity in later melts.

[Pete VanderLaan]

And now lets hear from the Amen corner....

[Brice Turnbull]

Alright, so I melted some blue, and whaddya know, but it turned out blue!

Better than that, it is compatible!

I melted the aforementioned recipe (which I will repost soon), excepting the copper, which I couldn't find on Melt Day.

I made a little cup, and cut it with a diamond disc blade into 4 cross-sections, with no cracking. I encased a big chunk in a paperweight - 1/2 the total piece is the blue, the other half is the encasing sp 87 clear, and I've now blown about 10 vases and lamp shades with the blue, and so far everything holds together.

I tweaked the amounts a wee bit before the melt, since I did in fact find my calculator on Melt Day and could make more accurate percentage calculations.

I'll post a couple photos too (just 'cause I'm so excited).
Thanks for the help - and I'll refer back to this thread in the future whenct I melt me some color agin.

Cheers,
Brice

[Pete VanderLaan]

And this is the substantive basis for religions of all flavors. Milagro!

[Dave Bross]

Congratulations!

Addictive, isn't it?

[Brice Turnbull]

It is Dave!

Now that I've seen how long it takes to melt a batch of cobalt, I'm thinking..... when things slow down in town at the end of October, I might like to work on some new alternate colors as Rollin suggested.

And I'd still like a silver aqua, and an emerald green might be nice..........

[Pete VanderLaan]

greens do strange and unfortunate things frequently. Chrome.... Ick.