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About Min

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    full time potter / moderator

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  1. 1) I use a couple recipes to do an iron wash. Simplest is just red iron oxide and gerstley borate mixed 50:50. Mixed up fairly thick then brushed on bisque then wiped off with a damp sponge, works from ^04 - ^6. It does flux so don't use it on the bottoms of pieces. Second recipe I use is good from ^04 - ^10 and doesn't flux much, same method of application. Blackbird Slip 27.4 Red Iron Oxide 37 Rutile 8.2 Alberta Slip 27.4 Round pot is the first recipe and tiny succulent planters the second. 2) For the mug in your set of pictures I would do the iron wash first then dip the top in glaze. Just wipe off any glaze that gets on the iron part. 3) The trees just look like raw clay to me that has had wax resist applied then the pots dipped in glaze.
  2. Min

    posting a status update

    Hi Russ, glad you got it sorted. I don't know if the protocol can be changed to an opt out rather than an opt in setting but I'll try and find out. Hi Gabby, that box doesn't show up if you haven't okayed posting Status Updates on your profile page. If you unclick the tab I posted in my post above you will see the box is no longer there.
  3. Min

    Clay fatigue?

    I think of clay fatigue as fatigue from overworking clay on the wheel. Clay gets flabby with excess water and collapses. I don't think of the cone6pots post example as clay fatigue. Potter Fatigue, overworking with clay, very common this time of year.
  4. Min

    posting a status update

    When logged in to the Forum go to your avatar in the upper right corner of the screen and "Profile" then "Edit Profile". To have the Status Updates option you have to click the green tab to opt into it, it isn't automatic. Once this is done then when you are logged in the "Recent Status Updates" window will be open and you can type your Status Updates (in the box just below the title).
  5. Min

    Studio Photography

    @neilestrick, I was but want the option to go in another direction. Think my problem was I was looking for one setup for taking all shots and some of my pieces can be too big for my current cube tent. For bigger pieces I think I'm going to try make up some diffusion panels to go in front of the lights from parchment paper or something. Thanks for the suggestion of renting lighting Callie but I went ahead and ordered better bulbs and reflectors from Amazon Canada. My last lights came with tripod stands, bulbs and reflectors. One of the bulbs actually separated into 2 pieces and the reflectors don't stay attached to the tripods.
  6. Min

    Studio Photography

    Thanks Mark and Neil, I have one of the white tent/cube setups but find a lot of my pieces are too large for it so I tend to not bother setting it up and actually using it for anything. I'm trying to weigh the merits of either getting a larger one or going for some lights like these and skipping the tent/cube. Is this a 6 of one and half a dozen of the other type scenario?
  7. Min

    Glazed over holes

    If you have to drill them out then start with the smallest size diamond bit you have to make a pilot hole then swap bits to the finished size. Also keeping a slow stream of water on the area you are drilling out helps the bits last longer. I made buttons for a while, used a round toothpick dipped in water then pushed through the buttonholes to clear the glaze out. Like others have said far easier to prevent the problem rather than fixing it.
  8. Min

    spectrum underglazes

    Just to add a bit to what Neil said, the structure of the stains used in the underglazes will make a difference in how the underglazes combine. Some stains have a spinel structure like many of the blues, greens and browns. Other stains are based on a zircon structure, like the vanadium turquoises and praseodymium yellows. If the stains are made from the same system they should be compatible and can be blended together to make predictable secondary colours. Chrome tin stains used to make reds, pinks and some purples are not going to be as stable as the two former methods. There is also the relatively newer method of getting the bright reds, yellow and oranges by using cadmium encapsulated zirconium silicate. With stains you can look at the info the stain company gives you and get an idea of which method was used for a particular stain. Examples would be if you took Mason Canary Yellow and Robin's Egg blue, they in theory should combine in a predictable way as they are both made using the zircon structure. But, if you used Delft blue and combined it with the Canary yellow you won't necessarily get what is predicted as each of those stains is based on a different structure. Anyhow, just a bit behind why some underglazes (and stains) don't combine in a predictable way.
  9. Min

    Studio Photography

    For indoor lighting what type of bulbs are best when using a lightbox? Tungsten 250Watt 3200K?
  10. Min

    Alumina Hydrate or Oxide

    Fire some and weigh the LOI. Alumina hydrate is Al2O3.3H2O and alumina oxide is Al2O3 so the hydrate is going to have a higher LOI, about 30% Like Callie said for wax it won't make a difference, might actually be able to use less if you have alumina oxide but since you use so little it's a bit of a moot point. If you were to use it in glazes for some reason (unlikely) it could make a difference.
  11. Denice

    Min I don't think I took any photos of the dishes,  I was working at my store 70 to 90 hours a week and made the dishes when I had a moment to spare.  My friend wanted a entire formal place setting so her daughter didn't have to eat off of plastic dishes at family dinners and holidays.   I made the entire formal place setting including cups and saucers,  they were mostly for looks.    I believe I made the soup bowl with no rest on it.  I can tell you that I had a lot more curve inward at the top edge and it curved further around.   The had rest was added to the lowest side of the curve.   A half round shape,  my friend wanted it so her daughter couldn't flip the dish when she laid her arm down.    She couldn't gently lower her arm.   Can the lady you are making it for try it out?   Denice

    1. Min


      Hi Denice, thanks for the info. I don't think I'll need to put a rest on it but what you did sounds interesting. :) I'll know tomorrow if my plate works. 

  12. Min

    Understanding COE

    @Hulk, in light of the current thread it would be interesting to see what we would all do to adjust your crazing recipe. Don't know if you are at liberty to post the recipe but if so it might be fun. If you do, posting a clear gloss recipe that doesn't craze on your clay and what clay you use would be helpful too. edit: Plus the qualities in the glaze you are looking for.
  13. Min

    Understanding COE

    Volumetric line blends are a quick and easy way to fine tune the degree of gloss / matte in a glaze. Line blends work and they're simple, especially useful for potters who don't use glaze calc software. Sorry to hear they make your head hurt.
  14. @oly, to get a fuller picture of the total costs I would really suggest looking into duties and brokerage fees also. I ordered a 2 piece splash pan from Bailey's in the US a few years ago, I forgot to specify how I wanted it shipped and Bailey's used a courier company, the brokerage fee was more than the splash pan. ($40-) Shipping by courier might be more convenient than a countries national post but I've always found that in Canada the brokerage fees are far more expensive than those from the national post and can add a significant cost to the total. I no longer buy anything from the US unless it can be shipped by US Postal Service. The recipients country will dictate the taxes that will be collected also, baseline for exempt or taxes due varies by country.
  15. Min

    Understanding COE

    Bear in mind that calculate expansion figures, while useful, are not absolute. Glaze calc is helpful to get you in the ballpark but there are limitations. First off, they don’t work for glazes that aren’t a fully melted gloss. Semi-matte and matte glazes are crystalline structures (as is clay and slip). This means part of the glaze is not fully incorporated in the glaze melt. In the case of semi or matte glazes some of the oxide(s) precipitate out of the glaze matrix. Calcium, barium, strontium, alumina and magnesium matte glazes are examples of this. Another point is glaze materials don’t always effect the coe in a predictable way. Example would be if you add zircopax to a glaze. With glaze calc the coe will rise with the addition of it. But, the zircon in the zircopax doesn’t actually enter the melt and although the coe raises (and the predicted raise in the likelihood of crazing) just by looking at the figures doesn’t tell you this, adding zircopax in actuality will lower the likelihood of crazing. Colouring oxides can have the same effect, theoretically raising the coe but in practice will often reduce crazing. There also comes a point where an oxide can be oversupplied, the coe figure might be low enough to assume the glaze won’t craze but it will. Examples of this would be an excess of silica or boron. There are limits to how much silica a glaze can take in without having excess silica not entering the melt. When this happens you will likely will see crazing. With boron, excess of it will negate the elastic effect it has on glazes, and again you will have crazing. There is also a rather confusing school of thought regarding the combination of oxides and the validity of coe figures altogether. If you take a well fitting glaze and add another oxide the coe can remain the same and yet the glaze can craze. COE figures work more accurately within a "family" or glaze system rather than by comparing two different glazes. The clay company I buy from, Plainsman, does not publish COE figures, "The reason is that such numbers often mislead users. First, a body has different thermal expansion characteristics when fired at different temperatures, schedules and atmospheres. Dilatometers are only useful when manufacturers can measure bodies and glazes over time and in the same firing conditions.” They give a very good write of the claybody properties and suggestions for glazes. Glaze calc and coe figures are a big help but at the end of the day, it comes down to testing, testing, testing.

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