Any time. Just use the deflocculate-and-siphon method you were using with your other batch to make it. If you don't have Darvan, just use the appropriate amount of the deflocculant you do have. Most studio potters don't own a ball mill unless they're really into refining their own materials. They're loud, and ball milling can take days. Like I said, Greg was trying to get more of the right sized particles for sig out of a single batch, and he happened to have access to the equipment. The siphon method is a lot more practical for most.
Edited to add: if you're worried about wasting the bottom layer, it can be used as a regular decorating slip. Just don't put it in your reclaim because of the deflocculant.
Ok. I went and dug up Greg's black sig recipe.
His method did involve ball milling and boiling, as he had access to a ball mill as an instructor in an institution and he wasn't as worried about production times. His primary reasoning for using the ball mill was 1) to get the most possible sig out of a recipe, and 2) cobalt oxide can be speckly once fired. If you choose to use the deflocculation and siphon method to make sig and use cobalt oxide, you may get some subtle speckles. I personally find it attractive, but if you are after a smooth flawless colour, it's something to take note of.
20 Red Art clay
1 Black Copper Oxide
2 Cobalt Oxide
1 Manganese Dioxide
If you have other stains available it would be a good idea to run tests with the other colors. Change only one thing at a time so you can nail down the effect of each different variation. If you get the same hazing with the different stains, then go to the ball clay and start over with the brown. Your other option would be to use the ball clay with the brown stain and see what effect you get...if the hazing goes away, you'll know it's your clay. Good luck with your testing
Adding stain can affect how a sig burnishes. It may or may not polish up as well as plain sig. Based on your picture, I'd say you don't have enough coverage with the sig to get a really good polish. And any time there's clay showing through, or texture in the clay, the polish won't be as good. Smooth surfaces burnish up the best. Also, if you fire the sig too hot you can lose some shine. It's best to not go all the way up to bisque temps.
So this post is a bit important to me. I have experienced this a lot with different things throughout my life and it did me a disservice most of the time until I later realized what talent is and isn't.
talent: the ability to start something and do reasonably well in the beginning stages. ex: you pickup a brush and paint a flower that is pretty decent the first try, or you take piano lessons and are able to play the beginning music pretty well.
skill: the ability to practice relentlessly until you are able to become really good at something, which people will then later credit to your talent. ** SEE MIN's better definition below. **
So some backstory. When I was growing up I was pretty good at beginning most things. I did a lot of art stuff, I did some music and other things. I was able to enter almost any field rather quickly and do reasonably well. I was told I was "talented" many times. This boosted my ego and made me feel confident about a lot of things. However it didn't do me any good, because I was "talented" I never really put in the practice when things got hard. I would go back to something I could do more easily. Eventually I would not gain any progress and I would switch to something else. I repeated this same beginner to intermediate pattern over and over. The entire time being told by my parents that I was so talented and I can do anything I put my mind to.
Well anyone can do anything they put their mind to, that isn't some special "talent" that only some of us have. If you work hard, study and find someone to help you get through the rough spots; anyone can do most things well given enough time and relentlessness.
So if someone tells me I am talented now, I just reply, "Hard work and practice, not talent." I think most people then pause and are slightly confused at why I just didn't take their praise. But in the end I am trying to persuade them to use different words. I have an example of this in my real life parenting that I am already adjusting my phrases with my son.
I do a lot of polymer clay with my son. The kind you bake in the oven with lots of colors. We like making figurines from our imagination and then play with them later. I have made hundreds with him from age 2 to 6. About 4 months ago we were making some figures who had round balls as their body. I was rolling up balls and putting them together. He was trying to do the same. He looks up in frustration and says, "I am not TALENTED like you daddy. Can you make these nice round balls for me?!" I told him talent had nothing to do with it and that I had been playing with polymer clay since I was a kid his age. He didn't get it. I told him I wasn't going to make his clay balls for him. He got up in frustration and said he was going to go do something else. I made him come back and sit down. I plucked off 10 pieces of clay the same size and I said "Sit your butt down and make 10 balls the best you can. Start here and line them up as you go." So he started making balls. The first few were crappy because he had a bad attitude, but as he kept going he got better and better. By the 10th ball he had pretty much a perfect sphere. He looked up at me with awe. Like I had just unlocked the universe for him, and he was slightly peeved it was that easy to do in just 10 balls. I just said, "hard work and practice son." We sat there for another few hours and made more figurines.
Of course I have to keep re-enforcing this habit all the time, he still attributes hard work to "talent" a lot of the time. His school still has the "talent show" instead of the "show us your skills" show. Mostly because everyone around him always attributes things to talent. It is rather frustrating. Even his teachers tell us that he is talented in some of his subjects at the parent conferences. Yea he is real talented in reading... is that even a thing? Mostly because his mother was in his room reading books to him for an hour every night before bed and we made him relentlessly sound out his words and learn phonics when he was in kindergarten. Nothing talented about it, hard work and a lot of arguments.
The idea of being talented is much more romantic then just thinking about putting in a lot of hours, study and patience to get something right. I mostly attribute it to the optimism curve.
This curve above is basically how we learn about things. Everything is awesome when you first start something you are "talented" at. You are making great progress and things are going epic. Your uninformed optimism gets you a long way. Then things get hard. You start to realize your going to have to make some decisions, you have informed pessimism. Common things you say are, maybe this isn't the stuff I want to do, maybe I should do something else instead, you start finding things to do instead of what you need to be doing to get better.
Eventually you hit crisis of meaning, this is where you either decide it wasn't for you, or you just put it off forever. Then you either crash and quit, or you realize you have to get good at something it requires more than talent, it requires hard work, study, practice and finding help from others further along in what you want to do. Finally you have informed optimism!
I would say most people never make it to informed optimism. If someone says you are talented, they probably have never taken something all the way to informed optimism, because they would know that it isn't talent, but hard work that go you to where you are! I feel slightly sorry for these people as they probably are sad they never had any talents!
So yea. They mean well, but change their thinking!