claclana Posted March 2, 2012 Report Share Posted March 2, 2012 Hi! I Have some bought in store glass tiles ("Venetian tile") with a very strong iridescent effect that I would like to have in my work, can you recommend some? Thanks!! Link to comment Share on other sites More sharing options...
Mark C. Posted March 3, 2012 Report Share Posted March 3, 2012 Some glass and glass tiles can be dichromatic which is really iridescent-I’m not able to recall that process for glass-not ceramic-I once knew it-(old brain) In ceramics I can say that mother of pearl luster can be near what you are looking for though its not as snappy. Luster like gold /silver/platinum/mother of pearl are cone 017 and cone 018 Very nasty/toxic off gassing occurs with these and precautions on application and fumes need to be addressed. I have not smelled luster’s in 25years but can still bring the exact smell up in my brain. If you want to simulate a migraine smell luster’s. Hopefully some luster experts will chime in on this. I still have all above-mentioned lusters –I feel they are best left in the bottles along with the headache. If your kiln is outside and or well vented and you wear an appropriate vapor mask and gloves your will be good to go. Mark Link to comment Share on other sites More sharing options...
Marcia Selsor Posted March 3, 2012 Report Share Posted March 3, 2012 You can also fume, but it is very toxic. Marcia Link to comment Share on other sites More sharing options...
neilestrick Posted March 3, 2012 Report Share Posted March 3, 2012 Another option, if you want to avoid the toxicity issue, is to approximate the effect with a high silica glaze. As the glaze gets glossier, the reflective quality can give an iridescent-like effect. Link to comment Share on other sites More sharing options...
trina Posted March 3, 2012 Report Share Posted March 3, 2012 black slip and copper oxide Link to comment Share on other sites More sharing options...
claclana Posted March 4, 2012 Author Report Share Posted March 4, 2012 YES!! thanks for your data!! Mark, I have noticed the lusters but didn't know about their toxicity and smell (and their prices) thanks! Marcia: fume with flame work / torch? like silver fume, but fuming what?...or how? Am I correct in assuming that high silica glaze with titanium dioxide, plus CuO can be the solution!? (or I am building a bomb here!!?)(I imagine that the black slip is to show off the iridescence even further, or does some contribution?) THANKS!!! Link to comment Share on other sites More sharing options...
Mark C. Posted March 4, 2012 Report Share Posted March 4, 2012 but fuming what?...or how You can fume a load of pots as it cools down around dull red heat-I have done this with the salt kiln a few times -results vary all over the load some are super some are muddy-some really bad. again this a toxic process with things like stannous chloride and other nasty stuff its expensive and if you want more control stick to luster's Mark Link to comment Share on other sites More sharing options...
canyon fox Posted March 5, 2012 Report Share Posted March 5, 2012 fwiw titanium dioxide encourages an iridescent effect - although more towards a pearl type opalescence. I was looking for a pearl type glaze, Glaze Mixer has "mother of pearl": http://www.glazemixe...er%20of%20Pearl Some potters say it's nothing but white, then others are talking about layering with Magic Strontium I thought, would be nice to mix my own. Slurrious , do you have a particular recipe for pearl glaze cone 5-6 you can share? Same question to Neil about high silica glaze for iridescent-like effect, your sharing will be greatly appreciated. Thanks, Lena Link to comment Share on other sites More sharing options...
Marcia Selsor Posted March 5, 2012 Report Share Posted March 5, 2012 YES!! thanks for your data!! Mark, I have noticed the lusters but didn't know about their toxicity and smell (and their prices) thanks! Marcia: fume with flame work / torch? like silver fume, but fuming what?...or how? Am I correct in assuming that high silica glaze with titanium dioxide, plus CuO can be the solution!? (or I am building a bomb here!!?)(I imagine that the black slip is to show off the iridescence even further, or does some contribution?) THANKS!!! bismuth subnitrate and silver nitrate . This type of fuming is done inside the kiln. It is Process of introducing metallic salts into kiln or onto wares at about cone 018, producing thin layer of metallic surface iridescence. from CAD Marcia Link to comment Share on other sites More sharing options...
Marcia Selsor Posted March 5, 2012 Report Share Posted March 5, 2012 For rainbow luster I have sprayed Stannous chloride onto crackle white glaze after firing and before reducing a raku. For gold luster I have used ferric chloride the same way. Fir irridescent fuming of a salt kiln I have waved a metal can of stannous chloride in the kiln after salting. It looks like carnival glass which I didn't like. Marcia Link to comment Share on other sites More sharing options...
Guest JBaymore Posted March 5, 2012 Report Share Posted March 5, 2012 Remember that the results of in-kiln fuming work are very much a mega-thin layer sitting on the very surface of the ware. That surface is very prone to damage and wear. So this is not for "functional" work (as in food service and the like). If you want something a bit more durable (but still not bulletproof) look into true Persian Luster glazes. They contain reducible metals and the kiln is fired in a soot producing level of reduction on the cooling phase until below color. Everything is covered in soot when you remove it from the firing. Then you clean it up and "poof" there are stunning lusters. Requires not only a fuel burning kiln, but a place where you can make carbon SMOKE without "issues". For the easiest approach, use commercial liquid lusters. Toxic to use and fumes from kiln are bad, but they work, are reliable, and produce a decent surface (again not highly durable). You trade off $$$$ in buying them for the "it works" factor. best, .....................john Link to comment Share on other sites More sharing options...
Pres Posted March 5, 2012 Report Share Posted March 5, 2012 Remember that the results of in-kiln fuming work are very much a mega-thin layer sitting on the very surface of the ware. That surface is very prone to damage and wear. So this is not for "functional" work (as in food service and the like). If you want something a bit more durable (but still not bulletproof) look into true Persian Luster glazes. They contain reducible metals and the kiln is fired in a soot producing level of reduction on the cooling phase until below color. Everything is covered in soot when you remove it from the firing. Then you clean it up and "poof" there are stunning lusters. Requires not only a fuel burning kiln, but a place where you can make carbon SMOKE without "issues". For the easiest approach, use commercial liquid lusters. Toxic to use and fumes from kiln are bad, but they work, are reliable, and produce a decent surface (again not highly durable). You trade off $$ in buying them for the "it works" factor. best, .....................john They are fabulous for effect, but ooooh boy do they stink when applying and firing them! Link to comment Share on other sites More sharing options...
canyon fox Posted March 5, 2012 Report Share Posted March 5, 2012 "...do you have a particular recipe for pearl glaze cone 5-6 you can share?" the only one i know is fired to ^8-9 in oxidation and uses volcanic ash. the glaze enjoys the cooler spots in the kiln and i know volcanic ash can sometimes be substituted for feldspar and silica so i can offer a starting point of sorts. feldspar 42 silica 18 whiting 23 Boraq 10 titanium dioxide 6 tin oxide 0.5 the Boraq is a gerstley borate substitue http://digitalfire.c.../boraq_124.html i've since added more silica to prevent some crazing. the last batch i mixed up had 10% added but i do know i've lost the opalescence with added silica approaching 15% iirc. where thinner this glaze produces a nice opal effect. where thicker it's white with a subtle opal sheen. there are occasionally some small clusters of tiny blisters that aren't really much of an issue except to annoy me. the claybody is a plainsman 550 http://plainsmanclay...m/data/H550.HTM this glaze was a bit of an obsession for longer than i care to admit and i can understand why some people might want to keep their recipe close. but i feel it is my duty to pass this harlot of a glaze off on someone else. so if you find yourself a year from now still chasing an opal/Chun/Jun glaze take heart - there have been a few before you. http://www.jonsinger.../rutilejun.html *i forgot to add 1-2% light magnesium carbonate or some other suspension agent Dear Slurrious, thank you for your reply and the recipe. The Blues on the last link look absolutely beautiful! Is there a way to adjust this recipe to cone 6? Or the whole point of getting effect is to fire high? Link to comment Share on other sites More sharing options...
Marcia Selsor Posted March 6, 2012 Report Share Posted March 6, 2012 ya i found myself at Jon Singer's site more than a few times wishing i could find something near as nice. i've never tried to lower the firing range of a glaze but a few things come to mind. The whiting(high temperature flux) can be reduced by 15% or so. in the original recipe whiting is added to the boraq to make boraq3 which is recommended for higher temperatures. boron(flux) is another option. adding boron in the form of boraq will lower the firing range but adds silica so you might consider reducing the silica as well. you might want to reduce the silica anyway. i know the glaze melts well at an 8 but changing from volcanic ash to feldspar and silica will change things a bit. if i were trying to test this glaze at a 6 i think i'd mix three. one as is, one with 15% less whiting and one with ? 5% more boraq and 3% less silica and less whiting. i suppose ideally a person would change one thing at a time and see how it affects the melt and colour but that's only the ideal. another thought - zinc oxide plays well with tin and titanium. i can't remember what amounts i tried or what the result but zinc oxide is very active flux in low amounts so another test with 1-2% zinc oxide might be fun. crystal glazes have a lot of zinc with titanium so there is definitely something along this line. anyway it's fun trying to think through a glaze - hope this helps *the zinc thing got me wondering - turns out i never tested small amounts of zinc on it's own. it was always with dolomite or wollastonite. If you come to NCECA, you should try to meet Jon. He carries his latest glaze tests with him. He is a very serious glaze guru. Marcia Link to comment Share on other sites More sharing options...
Guest JBaymore Posted March 6, 2012 Report Share Posted March 6, 2012 it's as good of an excuse as any to fiddle with a glaze. Ahhhh...... beware the Dark Side. best, ...............john Link to comment Share on other sites More sharing options...
canyon fox Posted March 6, 2012 Report Share Posted March 6, 2012 Slurrious, thank you for taking time to “think through a glaze†for me. Can I go with Gerstley Borate instead of Boraq? Just trying to go with what I already have. Thanks! Lena Link to comment Share on other sites More sharing options...
pixie1035 Posted March 8, 2012 Report Share Posted March 8, 2012 Hi! I Have some bought in store glass tiles ("Venetian tile") with a very strong iridescent effect that I would like to have in my work, can you recommend some? Thanks!! Link to comment Share on other sites More sharing options...
pixie1035 Posted March 8, 2012 Report Share Posted March 8, 2012 dark brown clay body with thick red iron oxide wash after bisquing... comes up a nice silver Link to comment Share on other sites More sharing options...
pixie1035 Posted March 8, 2012 Report Share Posted March 8, 2012 Hi! I Have some bought in store glass tiles ("Venetian tile") with a very strong iridescent effect that I would like to have in my work, can you recommend some? Thanks!! Link to comment Share on other sites More sharing options...
Brandee Ross Posted August 30, 2012 Report Share Posted August 30, 2012 Off topic: I think someone probably clicked on that by accident and would not let it affect your further posting on this forum! Link to comment Share on other sites More sharing options...
Marcia Selsor Posted August 30, 2012 Report Share Posted August 30, 2012 YES!! thanks for your data!! Mark, I have noticed the lusters but didn't know about their toxicity and smell (and their prices) thanks! Marcia: fume with flame work / torch? like silver fume, but fuming what?...or how? Am I correct in assuming that high silica glaze with titanium dioxide, plus CuO can be the solution!? (or I am building a bomb here!!?)(I imagine that the black slip is to show off the iridescence even further, or does some contribution?) THANKS!!! google Biz Littell Vapor Fuming Below is from Gary ferguson's Raku Newsletter. * Glazing * Vapor Glazing There was a question emailed to me after last month's issue as to "What is Vapor Glazing." So I did a little research and discovered an old issue of Clay Times - March/April 2001 that had an article covering Vapor Glazing by Biz Littell. His technique is named "Kosai ware" which means "hue of light" and involves the use of precious metals such as gold and platinum or special salts such as Stannous Chloride. His process is to first bisque fire the piece, then glaze fire the piece to cone 04. Then the piece is fired a third time to about 1000F at which point the kiln is opened to cool down to about 800F. One to two tablespoons of stannous chloride crystals are quickly poured on the hot kiln shelf around the pieces (but not on the pieces). Then the kiln is closed for a few minutes to give the salts time to fume the pieces. This colorant effect is more permanent that the standard Raku copper matte flashing effect. These chemicals are apparently very corrosive so it is critical that the proper safety equipment is used - respirator, mask, gloves, etc. Link to comment Share on other sites More sharing options...
Idaho Potter Posted August 30, 2012 Report Share Posted August 30, 2012 As I read all your writings, it brought back to mind my university instructor, John Takehara. He did a remarkable series of pots (bowls bottles, jugs, tea service) wherein he used lusters. Started with gold and silver, but the silver tarnished to quickly. Switched over to platinum and added gold leaf to many. If he worked on the pots at school, he wouldn't allow anyone else in the studio. He was good about making sure no one would suffer from the ill effects of these metallics--except himself. H would work--hunched over pot after pot--for hours, and never wore any type of respirator. After several years, friends and associates noticed that his memory was rapidly failing. When he finally passed, it was attributed to Alzhiemer's with damage also to his respiratory system. The potter's world lost a true master of the craft because the respirator interfered with his view (he wore glasses) and became too much trouble. His exposure was not for a prolonged time--maybe 3-6 years--and he went downhill rapidly. Any of you who use ferric chloride (and it's cousins) or any lusters--be careful out there! Link to comment Share on other sites More sharing options...
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