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-   -   Phosphate melt questions (http://talk.craftweb.com/showthread.php?t=12319)

Josh Bernbaum 05-16-2019 09:28 AM

Phosphate melt questions
 
So I've got my color unit up again and I would like to do some phosphate melts in this new pot I threw in there. I'm going to be working off a formula we used at John's class which used SP batch with erbium as the base. I have that here, it's what I use for my clear, but I also brought some bags of the 87 plain (no erbium) that I picked up from the batch plant down there. I've used the plain a lot in the past so as to not waste erbium on some of the colors I've done where I'm just adding colorants to their base, and save a bit of money as I think it's a bit less expensive. Question is, without the decolorant, does anyone think I'd see a greenish tint to the opaline white I'm looking for? I'm prob overthinking this as is usually my MO, but if there were any objections based on experience that could potentially save me a wasted test melt.

Also, one more, someone recommended not letting the temp get below 2150 for phosphates. Any truth to this? Just asking because that's a bit warmer than my usual gathering/idle temps.

Thanks

Jordan Kube 05-16-2019 07:05 PM

I wouldn't worry about the erbium. Keep the phosphate opal hot. I have experienced snot and crystal formation at lower temps.

Josh Bernbaum 05-17-2019 09:18 AM

Okay thanks Jordan

Pete VanderLaan 05-17-2019 09:46 AM

While I don't have the recipe John wanted to use , it will be the case that calcium will cause a lot of issues from the SP. The new silica is remarkable in its clarity if the stuff you purchased is in fact new stock.

Phosphates don't do well if cooled down much. That's true of a lot of glasses. I tend to think the lumps in lead arsenates are caused by overcooling the melts to make rods. In general, glass doesn't want to be in a rod form anyways. The attempts we made up here with Marks TIT series turned to glasscrete when cooled. We kept the calcium out of those glasses and replaced with Strontium.

Shawn Watt 05-17-2019 09:32 PM

I also mix my phosphate in spruce with erbium. I have to melt pretty hot and long 2385 for 7 hours and then I take it down the the “squeeze “ 2185 and work it from there. It will get snotty if it gets much lower than that. I also have to use it up within a couple days otherwise it’s gets chunky and starts to creep Coe. I was bummed I didn’t end up making it to the class. It sounded like a great experience.


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