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Roberta12

Age of dry materials

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Roberta:

colemanite is also known as calcium borate. Typical analysis can run as high as 48% boron and up to 22% calcium. One of those products that varies pending mine location: most abundant in Turkey. Can use it at any cone, but the higher the temp; the less you need. I use to make a boro-silicate (sort of) type glaze for tile. Also use a pinch of it in crystalline glaze. Hard to come by in the USA. 

T

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2 hours ago, glazenerd said:

Roberta:

colemanite is also known as calcium borate. Typical analysis can run as high as 48% boron and up to 22% calcium. One of those products that varies pending mine location: most abundant in Turkey. Can use it at any cone, but the higher the temp; the less you need. I use to make a boro-silicate (sort of) type glaze for tile. Also use a pinch of it in crystalline glaze. Hard to come by in the USA. 

T

Thanks! I have no recipes that use colemanite.   I will have to think what to do with it.  Do you know what the shelf material is (in the picture) ??  Is it a shelf made for gas fire??  

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Roberta, Colemanite was available in the 70's and got replaced by Gerstley Borate. The analyses of the two aren't identical, but Gerstley is subbed in for Colemanite with some adjustments, kind of like min spar/Kona.

Added

And those are some very nice carbide shelves. They're the fancy lightweight ones. 

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8 minutes ago, Callie Beller Diesel said:

Roberta, Colemanite was available in the 70's and got replaced by Gerstley Borate. The analyses of the two aren't identical, but Gerstley is subbed in for Colemanite with some adjustments, kind of like min spar/Kona.

Added

And those are some very nice carbide shelves. They're the fancy lightweight ones. 

And speaking of Kona, there is a small bag of Kona as well.   Not sure what to do with that either.     Thanks for the info on the shelves.  There were two small chunks that did not have kiln wash on them., everything else is washed but in good shape.  They are going to a friend who gas fires.  

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+1 for what Callie said about Kona F4 and Minspar being very similar. Titch more silica in the Minspar, I sub Minspar in recipes in exactly the same amount as the Kona F4 is called for. Re Colemanite vs Gerstley Borate, I think a lot depends on the analysis for the two, both had variable chemistries.  In theory Colemanite has far more boron than Gerstley but in practice I know of many older potters who used them interchangeably. I also remember reading about the source for the Colemanite causing issues, some would spit onto kiln shelves more than others. I believe this was likely due to gypsum contamination. Maybe there is a reason he still had a bag of it from the 70's ;)

It looks like the black shelves are the conventional silicon carbide shelves not the Advancer ones.

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On 9/6/2018 at 4:49 PM, Fred Sweet said:

Roberta-

Try rubbing alcohol to remove the marker. Works well for most permanent markers, and is substantially less expensive than hairspray. You also won’t have to worry about overspray.

Fred

acetone works best ..or nail polish remover <-same thing.

.

 

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I had a friend receive a large quantity of chemicals from a family of a deceased potter. It was going to cost the family about $10,000 to throw away the chemicals which would have to be tested for toxic disposal. You might explain that to the family when you make your offer. That is a lot of good chemicals some of which are extinct.

I'd like to suggest to old potters out there to consider leaving your studio chemicals to someone so the family doesn't have to deal with disposal costs. There are lucky to find Roberta.

 

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2 hours ago, Marcia Selsor said:

I had a friend receive a large quantity of chemicals from a family of a deceased potter. It was going to cost the family about $10,000 to throw away the chemicals which would have to be tested for toxic disposal. You might explain that to the family when you make your offer. That is a lot of good chemicals some of which are extinct.

I'd like to suggest to old potters out there to consider leaving your studio chemicals to someone so the family doesn't have to deal with disposal costs. There are lucky to find Roberta.

 

Thanks Marcia.  I was trying to decide yesterday which things to combine, and which to keep separate.  I combined his cobalt carb with mine, silica, epk, A couple of other things.  I did not combine the rutile.  It is a little bit darker than what I have, but it still looks like it should.  I thought I would test some of those things first. 

As I am going through all of his carefully labeled bags and pails I just felt like I could not let these things go to waste.  You are right about it costing so much to properly dispose of chemicals.  So, 50 pounds of custer feldspar is going to Steamboat to a hard working potter.  The colemanite is going to a forum member.  The talc is going to a forum member, the shelves are going to Palisade Colorado, the dolomite and bentonite are going to New Mexico.  And on and on.  It's a way to create a legacy for  Steve Grandbouche.  And pass along a tradition.  

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