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Min

Member Since 31 Mar 2010
Offline Last Active Yesterday, 11:10 AM
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Posts I've Made

In Topic: Trouble With Red

Yesterday, 11:09 AM

 

One other thing I would do that I didn't see on the lab sites directions would be to wash the test piece that you are sending in with hot water and soap before sending it off. Have no clue if Cadmium would fume, doubt it though, but remember that thread John B posted from Carty about copper glazed pots leaching far less in the testing if they are washed first. Probably won't make a difference for Cd but not 100% sure.

 

Can't remember if I have ever mentioned this in THIS thread (not reading back now)... or anywhere here on the CAD forums.........

 

In Japan, the famous "Oribe" green copper glaze is loaded with copper.  One of the standard parts of using that glaze for Japanese potters (that is not all that well known here in the USA) is to take the pieces that are glazed with it and soak them in a solution made from crushed chestnut shells overnight.  Basically it is an acid bath.  It "clears" the hazy look of the glaze as it comes out of the kiln.  It is taking the "loose" copper off the surface and in the immediate surface layer of the fired glaze.

 

I also note that many "American" versions of "Oribe" greens are so loaded with copper that they cause little black microcrystalline surface silicate precipitations to form.  Those areas will be way less stable in holding the copper than fused glassy phase glaze.

 

The acid soak makes a huge difference in the look of the glaze. 

 

best,

 

......................john

 

 

Interesting read John, thanks. I wonder if the tannins from the shells are acting as a mordant in some way also?


In Topic: Glazing Issues

Yesterday, 11:04 AM

@ Andrea, if you leave the handle join with an obvious "seam" around it then you can totally avoid the cracks that can happen when blending the handle into the body. The glaze that fills the seam becomes part of the design, with pooling transparent glazes it can look really nice. If you google Mike Jabbur his mugs show this type of join. Also for cleaning up around mug handles a Kemper Clean Up Tool is really good at getting into the fine tight spaces to clean up any slip or excess scoring marks. A damp sponge on greenware works as well as sanding and no dust issues.

 kem_k24_lg_2.jpg


In Topic: Spraying Mugs.

09 July 2016 - 11:28 AM

"I do use a turntable and I do tend to keep the mugs elevated, usually on a bisqued chuck, and mainly to keep the outside glaze from contaminating my nice clean white inside - that's obviously why  I get misses on the tops of the handles."

 

If you wax your white liner glaze for a couple inches inside the mug, let it dry then put a circle of foam snugly inside the mug as a stopper then spray you won't get overspray inside. Take the foam out straightaway after spraying and wipe off any stray droplets from the wax. You can just use upholstery foam scrap for the circle of foam, if you can cut it from a fairly thick piece of foam you push it in farthest for the first mug you spray then insert it a little less for each subsequent mug and you won't get glaze from the foam getting inside. If the lip of the mug doesn't get enough glaze on it then just dip it upside down in a very shallow puddle of glaze, the wax on the inside will give you a clean line. If you have a bandsaw it cuts foam really easily and accurately, if not then a serrated bread knife works okay. If you do a lot of mugs it's worth the effort. 

 

This foam is for a different size mug, bit small for this one,  but gives you an idea of what I meant.

 

 

 

 

 

 
 
 
 
 

 


In Topic: Spraying Mugs.

08 July 2016 - 07:04 PM

Mug handles, knobs, undercuts, all the tricky stuff I just hold on to the pot with one hand and angle the pot so I can spray inside or underneath etc then gently and lightly spray with the other. The inside of handles etc get sprayed first then the rest of the pot. I raise pots up off the turntable on tuna tins or small cups so I can spray evenly right down to the bottom of the pot. I wear nitrile gloves and use critter sprayers.

In Topic: Crawling Glazes

07 July 2016 - 07:22 PM

ThanksMin and Marcia.
C6 but I'll get on with it.

 

For ^6 you will likely need about 30% + magnesium carb. The old Beady Eyes Recipe would be a good start. I found it really lived up to it's name, if it's too melty I would just add a bit more clay and / or decrease the frit. I've used it with 10 zircopax to make it a clean crisp white,

Beady Eyes ^6

Custer 25

Whiting 6

Magnesium Carb 35

Ball Clay (I used OM4) 10

Silica 8

3134 16 (can you get 3134 in Oz?) can't remember if you use that or 3124?

100

 

plus 10 zirco

 

this is another one, lots of ingredients, I came up with it when messing around combining recipes, it's more goopy than cracked earth looking.

 

crawl feb 2009
Code Number:

Minspar  15.90 

3134 20.20
Talc 5.30
EPK 10.60
Magnesium Carb 31.90
Zircopax 10.00
Nepheline Syenite 13.30
Calcium Carbonate 3.20
Ball Clay 5.30
Silica 4.20
119.90