Posts Tagged ‘frit’

Kelvin ticked away happily last night (and him ticking off the degrees, all 1425 of them, up and down the scale is definitely one of my favorite all’s-well-with-the-world noises), and I grappled with the porcupine some more, and so the evening was passed. I decided both that the sock is not hideous, per se (it’s only the mangled-ness that makes it so), and that it’s going to be bigger than I thought (despite the swatch, Yarn Harlot). This is a blow, because I will have to give it to my husband, and his foot is bigger than mine (for which fact thank goodness, I suppose), and therefore more sock will need to be produced before I can call it done. I asked him how short was too short for a manly sock, and he very generously said that he’d wear ankle socks if I needed him to, but the idea of the Manly Ankle Sock may yet prove more wearable than the artefact. I started the heel. Fun, fun, fun.

The night was an unmitigated sleep disaster. I could say it was because I was distracted by Kelvin’s doings (and it is embarrassingly true ad childish of me, that I always sleep worse when there’s something in the kiln) or I could say it was because I was distracted by the matter of having scooped 220g of (allegedly) pure angora handspun on eBay for about the usual cost of 50g and was wondering what to make of it, but I can’t say that, because I’d have to admit to buying more yarn on eBay. I could alternatively say I was distracted by the two-year-old singing sweetly to himself for two hours (between three and five a.m.), or I could suggest that I was musing on the mirror I was planning to start this morning… Anyway, all I can certainly say of last night’s sleep was that it reminded me of the old Yiddish joke about the two old ladies complaining about the food at the resort in the Catskills: such terrible quality —and such small portions.

I checked the kiln first thing, as of old. I had got it on a bit early, while the kids were in the bath, so it was finished and cool enough to open before I went out. I thought I’d leave it a bit longer than I often manage (I usually open it as soon as the temperature drops to 200°) since the slab might- with luck, would – be thicker than the 6mm standard, and slower to cool, so I didn’t really want to beg for an entirely unnecesary thermal shock event. So, how was it? Since you ask, fine. Unexciting, but fine. The surface was slightly bumpy, but it’s actually quite nice, and I’ll be perfectly happy if I can preserve the effect through the slump firing. The overall color – or transparency – was good. There are a few bubbles, but not so many that the clarity is compromised. The colored frits are a bit dull: the cranberry pink is disappointingly flat, and the erbium pink tint is so subtle it’s practically disappeared. But erbium pink tint is like that – I know it is. I only get anxiety about it because it’s such an expensive color (the cranberry is too, now I think about it). It’s silly to use it invisibly. The disc is a satisfyingly thickness, and evenness across the plane. No thin bits, no holes. I think it will play nicely with the drop ring. So the cake ring mold worked like a charm. The lining with Thinfire, not so good. The paper fell onto the glass and it will have to be scoured, as there’s a powdery effect all around the edge now. Ah well: t least it didn’t bake on like kiln wash does. Next time I think I will try keeping it in place with a high-temp-wire paper-clip/kirby-grip-type arrangement. The gritty details: top temp 1425° for 25 minutes, and a hold at 985° for 45 minutes.

And today I started a Frank Lloyd Wright inspired square leaded mirror. More on that later. If I can lay my hands on the preliminary sketch, I’ll scan it in here. It’s very pleasant indeed to be playing with lead again. It’s such lovely tactile stuff. Mmmm.

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I decided it’s time to make something in glass again. I know I don’t have enough places to sell it, I know sales are down in the bad economic times, I know it’s silly, but –

I found me an excuse.

I thought I’d at least tidy up my glass room. And as I tidied I found the hammer, which was hiding amongst the clear offcuts, ready for the transformation of same into coarse frit. Meanwhile, my husband, poor dear, keeps thinking he’s lost the hammer and has several times had occasion to enquire whether I might have happened upon it anywhere. We have, on each of these occasions, gone through the stages of a) me admitting I do indeed know where it is, b) me admitting where it in fact is, c) him asking – job being done – if I need it back and d) myself concurring that I do, “but only for a little while”.

I can’t face going through this process again.

image019And the clear scrap was very overflowing, so this project is quite obviously part of the tidying process. And I have a large cake ring that I bought with exactly this project in mind, so I took hammer in hand and wrapped the scrap in a big thick wad of paper and hammered till the demons were all squashed for the day. It being a relatively demon-free day, I tired quickly and therefore stopped while the scrap was probably still a bit too lumpy, but we shall see. The balance is difficult: the finer the frit, the less clear the resulting glass sheet will be; the coarser, the harder it is to work out the right firing schedule (high enough, slow enough – all guesswork at the best of times), or more honestly – the more obvious it is if you’ve done a bad job; and the more you hammer your glass, the more very fine bits you get, while reducing the outrageously huge bits to gigantic bits, and the gigantic to huge, and the huge to merely very large indeed and so on. But the grit/lump ratio definitely goes up, which is detrimental.

Yes, I know you could filter the stuff through some kind of sieve, but that would be another stage to complete under “timed conditions” (this used to mean mock exams, now it’s toddler naps). And it would mean more opportunity to release dangerous fine particles of glass into the atmosphere and breathe it in in the absence (I know: I’m an idiot) of the appropriate face mask. I suppose I feel that the dangers of pouring a bit of pounded glass from a sheet of packing paper onto a kiln shelf isn’t like – I don’t know – playing with asbestos playing cards, but I still don’t want to take more than minimal risk. Also I’m lazy, and I’m not too sure the results will be worth even the amount of effort I am making.

image021So it all went onto the shelf, with the steel cake ring around it (lined with Thinfire shelf paper, but not kiln washed: we dice with death and sneer at disaster) to try and contain it in a circle while allowing it to build up a little thickness. If I have added enough glass I will be able to go deeper than the 6mm basic thickness, but I’m not sure, because I didn’t employ any of the scientific tricks for working it out. Silly me. It’s too late to go back and do it now, and I don’t think it matters much in this case. I did something similar before, and I ws surprised at how much it melted down. So this time, I refuse to be surprised. It WILL have shrunk, by the Law of Frit, more than I think. And. I. Will. Not. Be. Surprised.

I also threw a bit of official Bullseye colored frit on top – like cherries and pistachio nuts –  to spice it up. If it comes out as I hope, I might put it to jump through a drop-ring mold for my next trick.

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More is less

I think this needed to be added to the frit tutorial. I’ve been thinking about it, and I’m not sure I was quite clear enough before, so here it is, spelled out in the least uncertain of terms:

  • More frit than you can possibly imagine is still less than you think.
  • Quite possibly it is less than you need.
  • Any less, it just won’t be enough, especially for pale shades. It will disappear. Completely.
  • So go heavy with it, and the finer the grade, the heavier you need to go.

So for powder, imagine you are trying to murder someone with a sodium overdose and that your frit is the salt; whereas for fine frit, you are merely trying to make them very, very ill.

Coarse frit is much more “wysiwyg”, so you can exercise relative caution.

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– and I have seriously stalled on making the decorations. I somehow didn’t get any made over the weekend at all, or any today. I sent off a cheque for the big Christmas fair too, so I am now really and truly committed to doing it. Yikes, help and double-yikes.

frit decorations

So here finally are some -not very good- images of the aforementioned decorations. The cat looking out of the window at a snowy landscape is about 2.5 inches across, and the others are just under 2 inches. There are various others – quite a lot of different trees (in the snow, with red berries/baubles) and several snowmen (wearing fedoras, assorted bobble hats and scarves of many colors, and at least one deviant snowman actually smoking his pipe – complete with 1mm wide smoke rings [why?] ) as well some angels, and black cats turn up around the place from time to time…

These frit scenes are “painted” with the following technique and tools:

  • a teaspoon
  • a cocktail stick
  • a tweezers
  • a small paintbrush with a sort of spatula/chisel end (this is lifesaver)

For a really frustrating, fiddly, self-torturing experience, the results of which will be well-nigh invisible, proceed thus: take a small amount of fine or powdered frit on the end of the teaspoon and knock it off with either the cocktail stick or the end of the paintbrush, depending on whichever you happen to have in hand at the time, trying to get it as closely as possible where you need it, and in a thick enough layer (you always need significantly more powder than you think as it seems positively to disappear when it’s fired). Reposition the frit more accurately with the back of the brush and very carefully sweep excess away from the painted area. Doing this without proper precaution just swirls the dust around as it moves in the faint draft you create (I did say it was tedious work), and any slightly out of position brush hairs also drag through the design. For powder, gently level off the domed frit you will likely have (no dome probably implies not enough powder). To finish sharpening the outline of the shape, use the chisel end of the brush again. Proceed to the next color. When all powders have been applied, add any grain frit elements (eyes, baubles, etc.), dropping them on one grain at a time with the tweezers. A single grain of fine frit will often stick irritatingly to the tweezers, but can usually be knocked off with the cocktail stick which you are already holding awkwardly in the other hand. Pray that you do not have to do this – it’s the most risky part of the job and if you get it wrong, you can have a lot of reworking to do. Don’t drop that cocktail stick! Alternately, try using a fingernail (but be warned, the frit can end up just transferring onto that, which is the main advantage of the stick).

A note on sorting frit: be aware that there is quite a wide variation in the sizes and shapes of individual grains within a given size, at least with the Bullseye frit I use. Take a small spoonful and sort through it for, say, a likely pair of eyes that match (somewhat).

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Really  exciting: I had a frit painting work commissioned the other day, from a woman who had bought something off me through Etsy and had seen one of my bowl there. I have done a couple of plates and a small bowl in a Japanese-inspired cherry blossom design, and now I need to make a larger bowl. This design relies on a quite nice pinky-purply medium frit that is float compatible and came with the kiln. The woman I bought Kelvin off only used float glass – no wonder she got bored and moved onto lampworked beads. It turns out that while the base glass is cheap as chips and readily available, all the “float-compatible” stuff costs a fortune and is pretty hard to source, and mostly, it’s not that interesting.

At the risk of sounding like an advertising feature for them, I do think Bullseye glass is spectacularly nice to work with. The range of colors is fantastic, and the glass has depth, texture and character to it: it is prone to tiny bubbles that give it individuality. I love it. I love it. I love it. I just wish it were less expensive (relative to – say – Spectrum glass, which is boring and looks dead).

So, anyway, I mostly used the float stuff for a while, largely because I was never quite able to bring myself to invest in costly glass, mostly because I felt so much at the bottom of a very steep learning curve that it didn’t seem reasonable to do so. But eventually I did buy glass, as I’ve said recently. One of the first things I bought was black powdered frit, for painting. I was originally planning to use it to outline Babar the Elephant for a bowl for my daughter, but I haven’t got around to that yet.

Meanwhile, I thought if I used a very tiny amount, it should be compatible enough with float not to cause a problem. I think I got this idea from a lampworker talking about the 5% rule (up to 5% non-compatible glass being OK). I’d have to say that the cherry blossom design uses way less than 5% and looks alright, but I did push it a little further recently with some white Bullseye frit on a float and float-compatible stringer plate and it was not at all fine. The plate cracked after about an hour, and I really didn’t use that much. I should have photographed it to have some kind of record, but of course that’s the kind of thing you only think of a week after the glass has gone to the recycling…

The other thing worth noting was that the three-layer arrangement I’ve been using in the kiln doesn’t work half so well with float glass. I’ve been sticking something to slump on the bottom, something to slump or fuse in the middle, and something to fuse on the top. When it’s all Bullseye, that’s been fine, even with a top temp as low as 1325°, but when it’s all float… At 1400° for 15 minutes, the frit decor on the disc on the top shelf is well fused, but the middle shelf is barely tack fused, and the bottom – while slumped – is quite hard-edged. Still I think it’s come out quite nicely in the end. Since it was a commission I am doing a spare, or back-up dish a day behind the first one (so fused on the top shelf last night and set to slump tonight) to be on the safe side and I will send the client whichever comes out better.

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I did a really stupid thing last week. I was cutting a 12″ disc using my new second-hand-from-eBay Silberschnitt circle cutter when a slight crack appeared running in from one edge. At the time I was pretty pleased with myself for getting the disc out neatly without it breaking across at the crack. I thought it would close up again in the kiln. Silly me. Probably that would have been the case if, a) I had been using two layers of 3mm glass rather than one, or b) I had thought to place part of the design over the crack, thus effectively providing the necessary double layer at that point.* As it was, with a firing to 1345° for 20 mintes, the crack opened up a couple of millimiters over a length of about two inches. Useless. And – by my standards – an outrageous waste of a square foot of glass. Not to mention that some of that glass was the ludicrously expensive sunset coral.

I have spent much of the last week mitigating this error. Otherwise known as throwing good time after bad.

First I thought about the possibilities of a) and b) above and decided to place another “leaf” over the troublespot where the crack had opened up. So the next night I did that. It didn’t work. The design could take the extra element, but the crack was still there, albeit smaller. A couple of days later I visited my friend and begged some coarse clear frit for repairs. According to Bullseye’s catalog, the coarser the grade of frit, the clearer it will come out of the kiln (I think they are talking about casting), so I figured I should give myself al the help I could get at this point, and the poor disc was already looking a bit sorry for itself and was risking devitrification with every additional journey into the heart of hotness…

Well, that sort of worked. At least there was no hole in it any more and there was some chance of turning it into a passable dish. Last night it went back in, in one of the new molds (the one they call the “round slumper”, which baffled me until I got the exact dimensions and then decided seems to mean “flattish dish”, but maybe they think that might look silly in a catalog).

OK. Not great. But OK. The mold is good, anyway. The dish is in the cellar, already.

*Put succinctly for the uninitiated, glass likes to be around 6mm thick. If you layer it thicker than that, it will tend to flow outwards at heat, if you use less thickness – i.e one layer of standard fusing glass – it will tend to contract as it tries to puddle into a 6mm-thick mass. Both these problems are minimized, if not eradicated, by a conservative firing schedule.

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