oldlady Posted June 8, 2017 Report Share Posted June 8, 2017 i love the transparency of the glaze i have been using for over a year now. it allows all the very tiny detail to show through the shiny covering. i use green because my work involves natural leaves with all their veins and edges showing just as though you had picked a leaf from the tree. when i use copper carbonate to make green, i know that i have to cover the entire pot heavily to get enough color. what bothers me is that the pot is covered with glaze, it is shiny, it is covered but the green seems to slide down inside the glaze coating and land in the lowest spot where it is very green while the sides look too pale. yes, i can refire with more glaze and get a more even coating of green but i am doing the same thing, adding to the low spots while evening out the coverage. the very same base glaze with a mason stain, in this case mazerine blue number 6300, applied the same way as the green, comes out fine with only a single firing. what is in the mason stain that makes the color stay in place and cover evenly? i will be contacting Mason and talking with their very generous technical person later today but i just wonder if those of you with the chemistry skills can let me know what is happening. i know they use something to opacify but why is the blue staying evenly all over the same shape as the green without sliding down to the low spots? the funny thing is that each mason stain has a different effect when used in the base. the use of praseodymium yellow, number 6433, covers the texture and flattens it out. the green stains i have muddy the colors and the transparency is gone. any ideas? the photo shows the pale green with the copper carb and it looks like it is just not enough coverage and this piece is flatter than the usual but next to it are a number of the mazerine blue that were sprayed the same amount and they are totally fine. the piece on the right is the overspray that has collected over the last year. it is always fine. why is it only the green? Link to comment Share on other sites More sharing options...
Marcia Selsor Posted June 8, 2017 Report Share Posted June 8, 2017 'morning Old lady, I think the ingredients of the stains are causing the differences. I had a pink one that just did not work with my chosen glaze. It got crusty. High alumina content. Are you following the reference guide for the glaze compositions? Maybe different stains for similar colors might work better with your glaze. Have you tried spraying the copper glaze? That one looks like the application may have been uneven. Hard to say. Hope this gives some room for thought to solve this problem. here is the reference chart. go down the stain list and check what is in the stains you are using. And then see if they are compatible with the glaze ingredients. http://www.theceramicshop.com/store/content/369/Mason-Stain-Reference-Guide/ Marcia Link to comment Share on other sites More sharing options...
oldlady Posted June 8, 2017 Author Report Share Posted June 8, 2017 marcia, i spray all the glazes. the one that looks uneven is just like the others on that shelf. i usually put more of the green on a piece because i know what will happen. as you can see, it does not seem to help. the entire point of my question is what makes the stains spray and stay evenly while the copper does not? sorry if i did not say it right. Link to comment Share on other sites More sharing options...
oldlady Posted June 8, 2017 Author Report Share Posted June 8, 2017 trying to post 2 photos of the same pot. the first one was bisqued and then sprayed. it looks too thin, but notice the dark corners. and notice the one below it, still lots of color in the low spots. i resprayed it and the coverage is better but please notice what happened in the low spots. the dark collection of color. Link to comment Share on other sites More sharing options...
neilestrick Posted June 8, 2017 Report Share Posted June 8, 2017 I wonder if it's settling in your sprayer cup and not coming out evenly, so you get areas with more and less copper. Link to comment Share on other sites More sharing options...
oldlady Posted June 8, 2017 Author Report Share Posted June 8, 2017 why does that only happen with the green? what does mason add? and why does just the green slide down the slopes? neil, the pint bottles were filled with this green glaze less than 30 minutes before spraying. Link to comment Share on other sites More sharing options...
GEP Posted June 8, 2017 Report Share Posted June 8, 2017 Maybe the copper fluxes the base glaze more, thus allowing it to move? Whereas the mason stains do not add any more flux? I would try a line blend adding increasing amounts of stabilizer to the green glaze. Link to comment Share on other sites More sharing options...
oldlady Posted June 8, 2017 Author Report Share Posted June 8, 2017 mea, what stabilizer? first time i have seen the term but it sounds like what i want to do. Link to comment Share on other sites More sharing options...
Dick White Posted June 8, 2017 Report Share Posted June 8, 2017 Can you share the recipe for the base glaze? Perhaps the glaze mavens will have a tweak to the base. As for the difference between the colorants, copper is a mild flux and can increase the flow of the melt. Thus, it will flow down any sloped areas leaving it lighter, and pool in low spots and stick in corners for a darker effect. Stains, while containing various of the usual metallic oxides to achieve the range of colors, are more like a colored frit. They melt the colorants in a proprietary glaze, cool it, and grind it into a fine powder. Having been already melted once, it will react differently in your base glaze than a raw oxide colorant. And each stain has its own peculiarity, hence the differing reactions of the blue, green, and praseodymium. Link to comment Share on other sites More sharing options...
GEP Posted June 8, 2017 Report Share Posted June 8, 2017 Is there kaolin in the recipe? kaolin is the most common stabilizer used in glazes. Ball clay is a common stabilzer too. Then make a line blend where this ingredient is increased in small increments. Link to comment Share on other sites More sharing options...
Roberta12 Posted June 8, 2017 Report Share Posted June 8, 2017 Old Lady, I have a chart, which I ordered from mason stains....it tells what is in each stain. Apparently there is something with your base glaze that interacts differently with the green than with the others. Good advice from previous responders! Roberta Link to comment Share on other sites More sharing options...
neilestrick Posted June 8, 2017 Report Share Posted June 8, 2017 30 minutes is long enough for a glaze to settle a bit. Do you shake them up right before spraying? Your copper carbonate may not be as fine a grind as the mason stains so it can settle more. Also, like Dick said, copper can flux the glaze a bit. Although to me it doesn't really look like it's running that much more, but rather that it's going on unevenly. You have large areas that are thinner that aren't related to the decoration, which means it wasn't applied evenly there. It may also help to opacify the glaze slightly. Link to comment Share on other sites More sharing options...
GEP Posted June 8, 2017 Report Share Posted June 8, 2017 oldlady, I agree with Neil's answer as well. Some of the uneveness looks like a spray pattern. Some of it looks like pooling. Two problems to solve here. (hehe this is like a crime scene analysis) Link to comment Share on other sites More sharing options...
Pres Posted June 8, 2017 Report Share Posted June 8, 2017 I have to constantly keep my green glaze agitated in the sprayer as it does the same thing. Mine is just using oxides though not stains. I also notice that there are linear high low spots. When you spray do you cross coat? Spraying first N to S then E to W? It may help some of this. best, Pres Link to comment Share on other sites More sharing options...
Min Posted June 8, 2017 Report Share Posted June 8, 2017 Agree that it's the copper fluxing the glaze and causing pooling. Need to increase the clay content of the glaze. Also, remember when we were trying to find a base for your green a couple years ago the newer copper carb you and I were using settled fast and I suggested adding some epsom salts solution to help keep it suspended? Are you doing that with this glaze? Even with epsom salts my copper still settles out in the bottom of the spray jar but just not quite as fast. Think you likely have a bit of everything going on, too fluid a glaze from the copper, spray pattern plus settling of it. Wow your glaze is thick, looks like pudding in that one picture. edit: just found your recipe, I would try a small test batch with 10 epk instead of 8. another edit: was thinking about what Pres said and looking at the thick glaze in the corners. Looks like you go back and forth along one side, turn the pot and go back and forth along the next side and continue until all 4 sides are done. If you do it this way then you are putting twice the glaze in the corners as there is along the middle bit of each side. make sense? Link to comment Share on other sites More sharing options...
Dick White Posted June 8, 2017 Report Share Posted June 8, 2017 Min's comments are good. Putting the recipe through glaze calc reveals that the alumina level is fair to middling and silica is in the lower range of conventional limits. A few extra EPK should stiffen it some while keeping the alumina solidly within range. Link to comment Share on other sites More sharing options...
Guest Posted June 8, 2017 Report Share Posted June 8, 2017 Love your work oldlady I just wanted to add that spray guns, more precisely their nozzles, do wear out from the abrasive materials used in glazes. Could this be a possibility? Link to comment Share on other sites More sharing options...
oldlady Posted June 8, 2017 Author Report Share Posted June 8, 2017 thank you all, i see that there may be a solution. yes, the glaze is as thick as pudding, yes i spray end to end but i am aware of NOT overlapping the corners, and yes, pudding needs shaking all the time. i have 3 different EZE sprayers that i have filed to make the opening larger and they all get used. glad to see that someone knows that i am not really crazy, it is happening. look at the gallery photos and see how the green slides down. min, i confess that i forgot all about the epsom salts. that was a busy time of year and i thought i would have time later. later has not yet happened. maybe after the 18th when i can relax. (someone define that word) sorry not to have been here earlier but i had to take my dog to the dawg wash in frederick, md. last evening while i was not looking, he found a nice pile of deer poop and decided it would look good all over him. now that he is clean and the antique and thrift stores in frederick have less stock than they did this morning, i need to mow the lawn, price all the stuff that came out of the firing, pack everything, put it into the car and get ready to drive to alexandria tomorrow for saturday's sale. minus the 9 big pieces that do not have enough color and that i was hoping to sell there. i sprayed them a lot, too. Link to comment Share on other sites More sharing options...
glazenerd Posted June 8, 2017 Report Share Posted June 8, 2017 Lady: I need to get to my other computer to look up some chemistry notes I have. Think I have that answer, but need to verify. Nerd Link to comment Share on other sites More sharing options...
Dick White Posted June 8, 2017 Report Share Posted June 8, 2017 Sale in Alexandria, eh? Where? If I can get away before or after my class I'll visit. Link to comment Share on other sites More sharing options...
oldlady Posted June 9, 2017 Author Report Share Posted June 9, 2017 waterfront park, 200 south union st block. booth 66. mea hopes to stop by in the afternoon. it runs until 6 pm. (ugh!) would be happy to see any member, especially one with some info. Link to comment Share on other sites More sharing options...
Marcia Selsor Posted June 9, 2017 Report Share Posted June 9, 2017 Old lady, I use mason stains in glazes and engages. I have also had some copper carbonate that seemed to be a larger mesh than I had previously used. I agree the epsom salts is a good solution. You have to add ahead of time so it dissolves before spraying. ..but you know that. Marcia Link to comment Share on other sites More sharing options...
glazenerd Posted June 11, 2017 Report Share Posted June 11, 2017 Lady: Been thinking about this for a few days. 1. There is evidence this glaze is not heat tolerant. It is pooling and thinning: to the point that in some places; almost bare clay is showing. Do a test tile that has texture, so it will replicate the detailing in your pieces. Mix your glaze as per recipe: then add 1% alumina to the dry weight. See if we can slow down the flow. 2. Is this recipe high in sodium? 3. Peak temp of firing; with how much soak time? Nerd Link to comment Share on other sites More sharing options...
oldlady Posted June 11, 2017 Author Report Share Posted June 11, 2017 nerd, if you can give me an address, i would be happy to mail you a couple of tiny pieces so you can look at the worst and the best. i am not a good photographer and what you see might not be what you get. Link to comment Share on other sites More sharing options...
Magnolia Mud Research Posted June 11, 2017 Report Share Posted June 11, 2017 My suggestion is to add some kaolin to the glaze, use a line blend to get the needed amount. Nerd suggests alumina. I am concerned that alumina will add opacity.The reason the glaze does not run with Mason stains is because Mason stain does not dissolve into the glaze; solids in a slurry increases the viscosity just enough to prevent running but not enough to lower the transparency enough to be noticed.LT Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.