It snowed. Perfect snowball snow -- I tested. I also shoveled the walk, which was rather pleasant because the stuff was good on the shovel, and the air was above freezing. Unfortunately, the air is not above freezing now, and I have decided not to attempt to go to gamelan practice this evening. True, the roads are mostly clear, but any areas that were wet are now glare-ice or the evening equivalent. Thank you, no.
I continue to learn how to deal with the birds. Shiro bit me once or twice, but we have largely reached an agreement that biting is not appropriate behavior. The last time she tried it (nobody's perfect) was a few days ago; she grabbed my finger with one of her feet, and I realized what was about to happen just in time to angle things around a wee bit... whereupon she chomped on her own foot instead of on me. The reaction was prompt and pronounced. I hope she remembers it and is more cautious in the future.
She seems to have a passionate faunch for the soles of my sneakers, though, and I mostly just try to keep them out of her reach. (She's neurotic enough that she preens off all of the large feathers she can reach, so she is all down and can't fly; this helps. It is very silly, however, to be chased around the kitchen by a small white toddling blob of fuzz with an attitude.)
She also feels honor-bound to preen the ends of shoelaces, which rapidly results in the destruction of the little plastic protectors: these being equivalent to the sheaths on new feathers, they are summarily removed. Oh, well... at least she's a soft-spoken critter most of the time, unlike the other two. I was doing something with the Mac in the bird room today; it got so bad that I finally went upstairs and got my earplugs. Of course, once I ignored them for fifteen minutes or so, they forgot what they were arguing about, and became quiet again.
I think I already said that the birds seem to me to be rather like a cross between cats and dinosaurs: that is, something warm and fairly smart and somewhat cuddly, on the one hand, and something rather bizarrely alien on the other. If I had a handy microphone and a digitizer, I'd let you hear Shiro tromping all over the couch -- it's tremendously silly.
I really shouldn't say green -- Deadeye is a Green-Winged Macaw, but that means he's got some green on him someplace. When I can, I'll provide photographic corroboration.
He's has been doing his little kissy thing not only with my nose, but also once or twice with my finger. Needless to say, I only approach him when he looks like he really wants me to. None of that "nine-fingered Frodo" stuff for me, baby. I have pottery to do, and he would make a much bigger hole than Shiro can. (I think he weighs about 8 pounds, and he can crack a Brazil nut with total nonchalance.) Still, it is clear that he is fundamentally a friendly fellow; it's just very sad that he was abused as a child. (When Doug got him, he was in awful shape. He has come a very long way since then... but we mostly do not try to touch him. Doug can sometimes pat him a bit when he's just waking up, and after a few years of that he'll probably mellow a bunch more.)
Luna is small and somewhat shrill. She is difficult to understand at first, but one rapidly figures out that she has only a few things to say, most of which are "Go back in your cage, Deadeye!" During the last few days she has taken to flying over to me, landing on my head, and then banging the bottom of her beak on the top of my head, thomp thomp thomp. This tickles, sounds rather strange from the inside, and apparently looks very silly.
Boids, huh.
In Seattle, people fail to signal turns and lane changes. They slow down to a crawl if they see a single drop of rain, but they try to drive at full speed if they're on snow on top of ice. The speed limit on I-90 between Seattle and its eastern inner-ring suburbs is 60 (if memory serves), but most people try to drive 65 or so, some even faster.
Around here, they have signs on the road that say things like "Aggressive Driver Imaging In Use For Your Safety". Some of the traffic lights have strobes and cameras, so they can take your picture if you go through when the light is red. (No points, but they collect a fine or fee.) Just scary. The speed limit on the DC beltway is 55; most people do 70 or so if they can, sometimes even when it is seriously inappropriate. They push, they shove, they refuse to let other people merge if they can...
Maybe we talk about other things for a while. Bleh.
This is an older house, and the water piping was a mix of ancient galvanized iron and old copper (not a good combination to begin with -- let's make a battery & dissolve ourselves, shall we?). One day a few weeks ago we found the basement floor covered with water, and a peculiar spray and drip in the air down there. Kevin-the-plumber came by and did preliminary things, but it was clear that nothing short of ipecac was going to serve.
Over the past few days, there has been much sound of sawzalls (I believe that's a trademark), much vibration and dust. Ceilings were gored, and bled, and gave their all for modernity. Kevin and two helpers, in three short days, rewired the plumbing. I had intended to ask for a volume/temp control on my shower up here, but forgot. No matter, that's what they installed anyway. The only thing they haven't done is the bathroom in the bird room, and that will have to wait until the snow melts.
I’m on a few mailinglists, one of which (CLAYART) is devoted to pottery. One of the other participants, Mary Simmons, of the University of New Mexico, recently posted some analyses of a rather peculiar mineral called Gerstley Borate, about which I’m afraid I must comment.
No. I said, “Ghostly Bright”. ...Uhh, “Gristly...” maybe we won't go there. (Seriously, for some reason potters like to call this stuff by various silly names. Maybe that’s because they have trouble with it, or perhaps just that it’s easier to make up silliness from “Gerstley Borate” than it is from, say, “Clay”.) Not everyone who uses GB has trouble from it, by the way, but quite a few people do. That being the case, why use it?
From time to time there are reasons to want to add Boron to glazes. We usually prefer to avoid soluble forms like borax and boric acid, for reasons I may go into on the pottery tech page some day, but will not address here; this leaves us precious few alternatives: a few boron-bearing frits, a mineral called colemanite that a few people seem to favor, and this Gerstley borate stuff.
In pottery terms, a frit is a material that has already been melted, and is offered by the manufacturer as a powder. Frits let us use materials that would otherwise be soluble by putting them in the form of what is essentially glass. (Once you melt things together, if you do it right, they become much less soluble.)
Another aspect of frits is that they are available in a variety of compositions; you can get frits that contain boron or barium, frits that have lots of calcium but very little sodium or potassium (and vice versa), frits with low thermal expansion and frits with high thermal expansion, frits with various melting points. The compositions are published, so you know what you’re dealing with when you add these to a glaze you are developing.
Of course, you can’t just pick what you want at random. Only certain compositions are available, unless you learn to make your own. Still, even commercial frits are very handy.
In high-fire pottery, we can sometimes think of frits and certain minerals as nearly equivalent ways to introduce fluxes -- oxides that melt the glaze. Those minerals include the feldspars, spodumene and petalite (these are lithium minerals that are very similar to feldspars but contain different amounts of silica), ...and Gerstley borate and colemanite, which contain some boron (in the case of colemanite, this is in the form of calcium borate; Gerstley is more complex). Boron can act as a flux, as a glass-former, and as a handy way of decreasing thermal expansion. It also has some effect on the development of colors, as do many things.
Boron is even more important in the mid-fire range, and may be good for earthenware glazes as well. In fact, I think its use is most restricted in high fire... but we do use it, and Gerstley borate is one of the most common forms.
I am slightly hazy on this, but I think that colemanite is a hydrated form of calcium borate, and Gerstley is a mixture that contains a high proportion of sodium calcium borate (ulexite), along with a certain amount of colemanite. At least, that's the impression I get from an article by Jeffrey Zamek about colemanite and Gerstley. Zamek seems to know what he's talking about.
Only one problem: the article is just a wee bit out of date. For reasons that may have to do with logistics and may have to do with the fact that potters represent only a tiny market, the company that was mining Gerstley stopped at the end of 1999. The suppliers assure us that they have about a year’s worth in stock. This is not terribly reassuring. Prices have already started to go up, and the end of the year is looking slightly bleak. If nobody panics, we'll all have a little while to redesign our glazes. The biggest issue I've heard people complaining about is that Gerstley tends to stay in suspension in the glaze a whole lot better than the frits do.
This, of course, suggests to me the idea of air-blown frits. (Today, frits are melted and poured into cold water. The resulting shards are then ground to powder.) perhaps if hot air were blown through a stream of molten frit, it would produce particles with different shapes...
...But that's neither here nor there.
I'm not an expert, and I think I'm going to refer you to the Zamek article, because I think he discusses it a bit. I use Gerstley to introduce a small amount of boron into my rutile blue; I suspect that I'll be able to switch fairly easily to, say, Ferro's #3134 frit, when I run out. On the other hand, pure luck, about two weeks before I heard that they had stopped mining I bought 50 pounds of the stuff, so it will be a while before I run out. As I say, we can only use small amounts in high-fire glazes.
Well, I don't recall having any, and some people swear by Gerstley, but I think I've seen people complain about running, pinholing, and occasionally crawling. Also unaccountable variability, which may be caused by variations in the composition or by small fluctuations in firing technique, or even perhaps by gremlins. Who knows?
I trust that "running" is self-explanatory. If I can, I'll put a photo up here to illustrate pinholing, a problem I tend to have with rutile. (...And I'm not alone.)
Crawling is something else entirely. It seems to have to do with the surface tension of the glaze melt. If the surface tension is high enough, or if the bisqueware is dusty or oily when the glaze is applied, sometimes the glaze will pull back from some areas and leave them naked. There are even glazes that do this in an attractive manner, giving a rough and irregularly reticulated appearance, and are used by people on purpose. More typically, however, crawling results in cursing and smashing noises from the general direction of the potter.
While I am definitely concerned with Gerstley, I am reasonably confident that we’ll find adequate substitutes, or that I will, if necessary, learn to make my own frits.
On the other hand, the analyses were compelling. Here, it was clear, is a person who can tell me forthwith the contents of the Magic Brick Clay I described in “That ol’ Brown Magic” and the EDAX analysis.
I got in touch with Mary, and she has most kindly agreed to perform a few analyses for me. I sent her a check (while not as expensive as I had feared, these are definitely not free) and samples of the Magic Brick Clay, the lovely fireplace ash from Roy and Kay Jolenbeck (I hope I've spelled their last name correctly), and the clay from the back yard here, which I'm calling "Dandelion" because it's a yellow clay, and there are tons of it lyin' around Doug and Lisa's (D and L's) back yard.
Sorry, hadda do it.
I also sent her a chunk out of my bag of Gerstley. She's looking at various examples, and I figured it couldn't hurt to add one more to the pack.
What I didn't know was that she needed everything to
be at 100 mesh or finer. Uh-oh. I left my jar mill in
Seattle, and the finest sieve I have here is 80 mesh.
Argh. We're working on it... I think she can grind
things, but it takes time and effort. Maybe I should
build a jar mill.
Pseudo-mailto: jon [at] bazilians [put it here] org
Last modified: Mon Jan 29 20:10:57 PST 2001