Jacqui Sosnowski Posted January 10, 2020 Report Share Posted January 10, 2020 Ok! So here’s my problem and I’d much appreciate any feedback from you amazing potters out there! i have made a set of plates for a client who specified ferric chloride raku firing. They are totally food safe having been thoroughly sprayed with Liquid Quartz (a fantastic food safe sealant readily available here in Australia). Now the client would like “a more smooth glazed finish” (understandably) on the eating surface so I’m wondering if I can re-fire them (or make a new set) to a low temperature with a clear gloss glaze without affecting the ferric chloride “glaze” got in the raku - only fired to 750 Celsius. Is there any low low low fire glaze that I can fire over the top that will be under 750 so won’t burn the ferric chloride off??? Link to comment Share on other sites More sharing options...
JohnnyK Posted January 10, 2020 Report Share Posted January 10, 2020 Welcome to the Forum, Jacqui! One of the wonders of Raku, IMO, is that EVERY piece in unique. You never know what the outcome will be. You can come close in trying to reproduce a piece, but they are like snowflakes, no two are alike, You can always try to refire, but there is no way to predict the outcome. You mention making a new set... try your refire experiment and if it works, you are good to go and you have learned something wonderful which, of course, you will share with us. If it doesn't work, you will have learned something that you will also share with us and you will proceed with making a new set. Either way you will have increased your knowledge base. Good luck! Link to comment Share on other sites More sharing options...
Min Posted January 10, 2020 Report Share Posted January 10, 2020 10 hours ago, Jacqui Sosnowski said: They are totally food safe having been thoroughly sprayed with Liquid Quartz (a fantastic food safe sealant readily available here in Australia). Have you had a sample lab tested? From the Liquid Quartz website: "If you use a post firing chemical (like ferric chloride) or any potentially toxic ingredient in the firing of your work that will not burn out at the temperatures you fire to &/or has nano sized particles, you should test your work to ensure no leaching occurs." I haven't used any glazes that fire to around cone 016. There is this one on Glazy but it doesn't look very durable and has a crazy amount of lithium in it. Whatever glaze you try putting over I think it's likely to significantly change the effect you have now. Link to comment Share on other sites More sharing options...
Jacqui Sosnowski Posted January 10, 2020 Author Report Share Posted January 10, 2020 I am thinking to maybe burnish and terra sig the hell out of them BEFORE I bisque. That will increase the smoothability on the plates’ eating surface without needing to glaze. Link to comment Share on other sites More sharing options...
neilestrick Posted January 10, 2020 Report Share Posted January 10, 2020 There are way too many warnings about what that product cannot do with low fire, porous surfaces. It specifically says that it cannot make a toxic glaze food safe. It says that prolonged contact with some foods may mar the surface. It says it will not make your clay body any more durable and less resistant to scratching, that it will still mark from cutlery and chip easily. If those were issues with a specific glaze we would not use it on functional work, especially plates. That product is simply a sealer, it should not be used in place of a good glaze, especially on plates. Raku should never be used for dishes, even with a sealer IMO. As soon as there's a scratch in the sealer, it's no longer sealed up. You're not only opening yourself up to an unhappy customer down the line after using the plates for a while, you're opening yourself up to liability. Link to comment Share on other sites More sharing options...
Min Posted January 10, 2020 Report Share Posted January 10, 2020 1 hour ago, neilestrick said: Raku should never be used for dishes, even with a sealer IMO. As soon as there's a scratch in the sealer, it's no longer sealed up They say as much on their own website, not even recommending using it on earthenware for functional work. " Note that if the surface you seal is not completely solid (lowfired/low bisque) the sealer will still fuse with the surface & be waterproof, but only for as long as the surface remains intact, therefore heavy scraping of cutlery on unstable bisque fired plates is not recommended. Earthernware clay bodies fired to their most vitrified temperatures (terracotta etc.) can be sealed with much success, but will remain more suceptible to chips & damage than high fired stoneware or porcelain, as the claybody itself is not suitable for restaurant quality plates, cracking easily & requiring gentle washing to prolong the life of the piece. This is the nature of the clay body, & cannot be changed by sealing the surface only. While your work will be waterproof & stain resistant, it will remain brittle & easily scratched if low fired". Link to comment Share on other sites More sharing options...
neilestrick Posted January 10, 2020 Report Share Posted January 10, 2020 Personally, I would only use a sealer product for pots that are not meant for use with food. I think Liquid Quartz is probably a great way to protect the surface of raku and other non-functional firing processes, though, for uses other than eating. I'm a bit confused, though, because the web site says it's been in use at restaurants since 2014, but then it specifically says that restaurants have to use vitrified ware, which begs the question- why do you need s sealer, then? Link to comment Share on other sites More sharing options...
Min Posted January 11, 2020 Report Share Posted January 11, 2020 1 hour ago, neilestrick said: I'm a bit confused, though, because the web site says it's been in use at restaurants since 2014, but then it specifically says that restaurants have to use vitrified ware There is a picture in their gallery of some stoneware plates that are only glazed on the top surface, maybe that's what they're referring to? Looks like the clay has to have some porosity but they don't quantify how much. "Liquid Quartz can be applied to all unglazed, porous surfaces; bisque ware, vitrified ceramic ware (yes it is still porous)" Link to comment Share on other sites More sharing options...
neilestrick Posted January 11, 2020 Report Share Posted January 11, 2020 6 minutes ago, Min said: There is a picture in their gallery of some stoneware plates that are only glazed on the top surface, maybe that's what they're referring to? Looks like the clay has to have some porosity but they don't quantify how much. "Liquid Quartz can be applied to all unglazed, porous surfaces; bisque ware, vitrified ceramic ware (yes it is still porous)" Porous, vitrified ware. That's a new one. Yeah, it's not very coherent in exactly how they intend for it to be used. Link to comment Share on other sites More sharing options...
Marcia Selsor Posted January 11, 2020 Report Share Posted January 11, 2020 I have considered buying Liquid Quatz for my soluble salts pots because I always worry someone will want to pout flowers in them. They claim liquid quartz is food safe and there is a restaurant using saggar fired ware with liquid quartz for their tableware. Which makes me think it would be interesting to fire it and see what it does. I am not sure you can cover Liquid Quartz with a glaze and fire it. You might be able to fire it without a new glaze. Do a test on a raku piece sealed with liquid quartz and see what happens. It could be a glaze, Marcia Link to comment Share on other sites More sharing options...
JohnnyK Posted January 11, 2020 Report Share Posted January 11, 2020 Well, yesterday I put in my order for a liter of the stuff. Fortunately, the monetary exchange rate made the purchase more palatable. I was looking for a way to seal the inside of my Horsehair Raku pots so they would hold water and this looks like it would fit the bill. I seal the outside with a clear acrylic spray, but that wouldn't work for the inside. I think that the process with the LQ will help increase the selling price of the Raku pots...allowing them to be used as vases in some cases. Link to comment Share on other sites More sharing options...
oldlady Posted January 11, 2020 Report Share Posted January 11, 2020 jacqui, sometimes the answer is simply "No." Link to comment Share on other sites More sharing options...
Mark C. Posted January 11, 2020 Report Share Posted January 11, 2020 Raku firing twice is risky for sure and hoping the effect of the 1st fire stays the same is asking for trouble. Now as to sealing a ferric chloride raku glaze with sealer-well thats just truble waiting to happen down the road. Australia may sell the stuff as food safe but its a sealer and can come off in so many ways-I'm with everyone else on this is just not something thats made to last and protect your clients from harm down the road.To many ways for it all to fail. Raku as dinnerware is a fleeting experience -the stuff is like a potato chip in terms of breakage anyway . Better to drill holes in those plates and hang them as wall art. Sealing tham should keep the color from oxiding for awhile . Link to comment Share on other sites More sharing options...
JohnnyK Posted January 18, 2020 Report Share Posted January 18, 2020 Just received my first liter of Liquid Glaze and used it on the inside of one of my Horsehair Raku pots following the mfg instructions and it worked! The inside of the pot is definitely hydrophobic...Filled it with water and let it stand for 4 hours with no sign of seepage. I'll leave the water in the pot for a couple of days to see if there are any adverse reactions. If none, then I think I'll have a new line of watertight Raku pots that can be used as vases...Hot Damn! Link to comment Share on other sites More sharing options...
Magnolia Mud Research Posted January 18, 2020 Report Share Posted January 18, 2020 Johnny, Test the vase with water that has a “tad” of soap and/or detergent to see if the “stuff” remains water resistant. Flowers often contaminate the water after a few hours; many florists put a package of powder that slows the wilting of the flowers. My guess is that the “liquid glaze” depends on the high surface tension and wetting character of pure water; adding detergent lowers surface tension and increase wetting. Or add some rubbing alcohol. Hopefully the “liquid glaze” lives up to the advertisement. LT Link to comment Share on other sites More sharing options...
liambesaw Posted January 18, 2020 Report Share Posted January 18, 2020 6 minutes ago, Magnolia Mud Research said: Johnny, Test the vase with water that has a “tad” of soap and/or detergent to see if the “stuff” remains water resistant. Flowers often contaminate the water after a few hours; many florists put a package of powder that slows the wilting of the flowers. My guess is that the “liquid glaze” depends on the high surface tension and wetting character of pure water; adding detergent lowers surface tension and increase wetting. Or add some rubbing alcohol. Hopefully the “liquid glaze” lives up to the advertisement. LT I think it's likely a sodium Silicate based sealer so it's probably fine against mild acid but will dissolve under strong base. Link to comment Share on other sites More sharing options...
oldlady Posted January 18, 2020 Report Share Posted January 18, 2020 and the scrubbing someone might give a nasty smelling vase that held an old bouquet that was forgotten over several days. Link to comment Share on other sites More sharing options...
JohnnyK Posted January 18, 2020 Report Share Posted January 18, 2020 Thank you all for your input...I'll take each of your suggestions and put the vase through the ringer and see how it holds up, but first I'll give the outside a couple of coats of clear acrylic to protect it as I usually do. Link to comment Share on other sites More sharing options...
JohnnyK Posted April 16, 2020 Report Share Posted April 16, 2020 It's been 3 months and I'm sorry for not getting back sooner on the first use of the Liquid Quartz...I treated one bowl on the inside, let it dry and then filled the bowl with water. After one day, I found the bowl to be damp with a yellow ring around the top of the bowl. I figured that what happened was that when I filled the bowl with the LQ, I did not fill it all the way to the top . However, when I filled it with water, I did fill it to the top and the water leached through, dampening the bowl and leaving the yellow ring around the collar. Needless to say, I was somewhat disappointed. I just sat the bowl aside and forgot about it until about 2 weeks ago when I put it in my kiln with a bisque load. I figured that it would burn off the LQ and maybe get rid of the yellow ring. Well, the ring was still there when I took it out of the kiln. I was still curious about the yellow ring, so I filled the bowl with water and sat it on a dish for a couple of days. Water had seeped through the bowl to the point where it was totally saturated and there were droplets on the bottom half of the bowl and to my surprise, the previous yellow ring was gone! Now the entire bowl has a slight yellow tint to it, but the big surprise was that the rim was now an interesting shade of chartreuse. So this is going to lead to a new set of experiments to see if the bisqued pieces of this clay (Laguna B-Mix ^5) turn yellow when H2O saturated, and also making sure that when I treat the pieces with LQ, I fill them to the top on a level surface. Another takeaway from this experience was the realization of how bowls that are used for African Violets work. The bottom of the bowl is unglazed which allows water to seep through to saturate the plant's soil from the bottom up, which, in turn, provides me with an idea for another product... Link to comment Share on other sites More sharing options...
Sorcery Posted April 21, 2020 Report Share Posted April 21, 2020 This product, Like Asbestos, is bound to have a disease named for it. What do you call silicosis of the liver? Sorce Link to comment Share on other sites More sharing options...
JohnnyK Posted September 14, 2020 Report Share Posted September 14, 2020 OK...As an ongoing part of this test series, I tried the LQ on another pot and it failed again, so I contacted the manufacturer about the problem. They asked me if I had thoroughly washed and dried the INSIDE of the pot before the LQ application. They said that even the smallest amount of dust or dirt could keep the LQ from properly and completely doing its job. I realized that I had not. Soooo...I'm going to try again, but this time I am going to seal the outside with a clear acrylic as I usually do after firing to keep the horsehair and feather residue in place before washing. Then I'll try again and keep you apprised of the results... Link to comment Share on other sites More sharing options...
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