Hulk Posted February 4 Report Share Posted February 4 From thread on target cone and crazing*, are you using 325 mesh (e.g. "Sil-Co-Sil 45" or 45 micron), 200 mesh (90 micron), or some other mesh silica for glazes? Ever used 200 mesh? If so, any crazing at all? How resolved? I am curious if others are using (or used) 200 mesh successfully**. This article https://digitalfire.com/picture/u2d1fdLBki got me thinking. I wonder if my glaze fitting struggles were related to 200 mesh silica (which is what I have)? If so, then, would more heat work help dissolve the silica? If so, then, would more and/or more aggressive fluxes help dissolve the silica? If so, would a drop & hold (after peak temp) help dissolve the silica? I don't know. The solution involved tweaking the formula to reduce COE, however, I'd adopted drop & hold at about the same time. Answers, hmm maybe testing. I have several small batches of glaze that crazed. I'll try resurrecting and then putting them through my current glaze firing schedule. More to the point, perhaps, would be get some 325 mesh to compare, heh. * https://community.ceramicartsdaily.org/topic/41078-crazing-versus-firing-temperature **David, in the thread linked above, had incurred crazing at cone 6 (but not cone 10) when 200 mesh was substituted for 325 mesh on error; going back to 325 resolved. Perusing the archives, 325 melts better; "; 325 is standard; "; 325 is for glazes; several recipe examples specify 200 mesh, or some of both 200 and 325; 200 mesh requires more heat work, or slower rate to achieve same heat work; 325 is standard for glazes, "Cone 6 needs 325 mesh, or additional fluxes for full melt of 200 mesh" per GlazeNerd; 325 melts better, go half a cone hotter with 200; 200 is cheaper, melts less and 325 has a better finish; commercial glazes may/do use 200; From John Britt's "Mesh Size" article linked to Ceramic Arts Daily, 200 mesh used to be the glaze standard (fifty years ago), "Using 200-mesh silica now may be closer to using 325 mesh back in the day." and 325 will melt easier. Quote Link to comment Share on other sites More sharing options...
Hulk Posted February 4 Author Report Share Posted February 4 ...and it's a rainy day here. Quote Link to comment Share on other sites More sharing options...
PeterH Posted February 4 Report Share Posted February 4 52 minutes ago, Hulk said: From John Britt's "Mesh Size" article linked to Ceramic Arts Daily, 200 mesh used to be the glaze standard (fifty years ago), "Using 200-mesh silica now may be closer to using 325 mesh back in the day." and 325 will melt easier. https://ceramicartsnetwork.org/ceramic-recipes/recipe/Mesh-Size# Quote Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted February 6 Report Share Posted February 6 50 years ago, the standard was also cone 10 reduction, and I think cone 6 was filed under “interesting but impractical.” So the extra heat work took care of the difference that the silica mesh size would have made. 200 mesh sil-co-sil was all I could get back in the 90’s, so I used it. And I was firing at cone 10 at the time, and it was fine. When I made the switch to cone 6, I came across much of the same info you’ve already listed, and the 350 mesh was more available. I was less concerned with crazing at the time, but I can say that the mesh size makes a difference in glaze clarity at cone 6. Hulk 1 Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted February 6 Report Share Posted February 6 The digital fire link seems a pretty good example of the difference a smaller mesh can make. The smaller the better in my opinion for melting silica. I remember back to my bubble experiments and removing quartz/silica additions and trying to source from feldspars/clays always had a better melt. Glazenerd did send me some super fine silica that is still on my list to test about 7 years later Callie Beller Diesel and Hulk 2 Quote Link to comment Share on other sites More sharing options...
Mark C. Posted February 6 Report Share Posted February 6 In the 70s silica and talc where what they where-no body knew that silica was 200 mesh or 325-the bags did no say much on them. When I asked most supoppliers only stocked 200 mesh (cheaper) All my silica was 200 mesh.. In the 80s I traded it all to a glass blower for his 325 mesh silica. Later in years the 325 became a thing in many other materials . When you bought talc in 1975 you asked for talc and you got a bag. (Neph syn was always in 200 or 325 mesh and was the odd one in this choice)There where zero choices. Life was simpler then no shortages, basic commodities, Like coffee now you can have it with 1/2 low fat 1/2 or 2% or all fat or almond milk or austrialian nut juice-well you get the point wayyyy to many choices In those days the talc was desert talc from Death valley (long ago closed up) or c talc. That has all changes now as well. Texas talc was a major shift for decades-talc which is grey in color. I now use 3-4 talcs . I only use the 325 in most materils if there is a choice for better melts and yes in the 70s cone 6 was not a thing but 06 was a thing. Back then we had what we called old lady slip shops that sold cone 06 stuff and did mold work (this area had 3 of them) and I got a wholesale accout at one for some materials and tools(all long gone for 35-40 years now) I knew of NO cone 6 users in the 70s and 80s-none only in the 90s did I become aware of that temp range. Now I should add I'm in a very high electric rate area maybe the highest in the counrty (Maine I think is higher). Its made ordering materials overcomplicated as well on my side as well. Hulk 1 Quote Link to comment Share on other sites More sharing options...
Morgan Posted February 11 Report Share Posted February 11 I kind of got burned by not specifically stating 325 on an order one time (lesson learned) so of coarse they sent the much cheaper 200. For some glazes I could not tell but others were super apparent and 325 gave a superior finish/melt. Hulk 1 Quote Link to comment Share on other sites More sharing options...
Morgan Posted February 11 Report Share Posted February 11 Also mark I’m living in HI and paying over 40 cents/kwh, it’s crazy. On 2/6/2024 at 7:38 AM, Mark C. said: Now I should add I'm in a very high electric rate area maybe the highest in the counrty (Maine I think is higher). Quote Link to comment Share on other sites More sharing options...
Hulk Posted February 11 Author Report Share Posted February 11 (edited) Mr. Hansen replied (on FB group "Clay Buddies"); question "Any chance that drop 100F from peak and hold 30 minutes helps the silica to dissolve?" Answer: "Certainly, the more time the more dissolves." and later, "Our main transparent glaze was not crazing either. At least that’s what we thought. On certain bodies it was crazing over time. Changing to the finer silica has definitely improved it. Silica is cheap, I would get some new stuff and use what you have to make Porcelain." My first kiln was certainly slow on the last 160°F or so. The new kiln, I've set the last ramp to just about match the old kiln. Perhaps the gentle/gradual final ramp to peak, drop 100°F to extended hold, and controlled/slow cool to 1850°F all help? ...and the mix of fluxes. Next run for heavy supply/material, I'll buy a sack of 325 mesh! Meanwhile, I'm still curious about others' experiences with silica "meshes" for cone 5/6 glazes, and thanks for the replies. Electric rates, whaaa? Our peak rate was 43.67¢/kw (off peak rate 40.83¢/kw); looks like 51.54¢/kw (48.7¢/kw off peak) since 1-JAN-2024, aah, the rates did go up! ...the "break even" point on our new (went online August 2023) solar array will be that much sooner then, eh? The utility (PG&E) does separate accounting on "peak" and "off peak" (peak for us is 4-9p.m., every day) usage, hence, limiting/monitoring peak usage does matter, particularly as there's little to no solar generation at that time during "winter"... Our house is on a North facing hillside. When the sun's arc is lowest (November through January), the shade hits the panels at about 2:15p.m.! During the design phase, I asked the Engineer if five more panels could be added. "Uhhmm, oook" they said. Edited February 11 by Hulk bold current rate (multiple interlocked pun fun) Quote Link to comment Share on other sites More sharing options...
Mark C. Posted February 11 Report Share Posted February 11 8 hours ago, Morgan said: Also mark I’m living in HI and paying over 40 cents/kwh, it’s crazy. Yes in the islands you burn imported oil for all power plants to make power-hence the $$$ for power-solar is your only way to change that. Our rate via a cooperative cities/county agreement with PGE (our supplier) on last bill was .42cents a KW . We have a large solar system with 22.5 k battery backup so we only use off Peak hour power which is cheaper power. As I said its one of the highest rates in USA excpet for Maine. even higher than yours. You may wonder how power on a island in the middle of the pacific has chaeper power than on the mainland west coast and for good reason-its NUTS. The majority of folks on this site have really cheap power (midwest is almost free)-east coasters are way less as well. Quote Link to comment Share on other sites More sharing options...
Morgan Posted February 12 Report Share Posted February 12 Whoa! I cannot believe it is that much mainland where you are, just wow! Quote Link to comment Share on other sites More sharing options...
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