tag:blogger.com,1999:blog-6574046592294768817.post6791714193643833163..comments2023-11-30T09:42:16.566-05:00Comments on Whynot Pottery Blog: Clearly we are getting somewherecookingwithgashttp://www.blogger.com/profile/11456258592273328486noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-6574046592294768817.post-76625914938395098342009-09-09T10:31:57.960-04:002009-09-09T10:31:57.960-04:00Patricia,
I would say that it significantly lessen...Patricia,<br />I would say that it significantly lessens the amount of testing you have to do. And if you use software you don't need any formulas. There are two ways to work on a glaze:<br />1. Take a recipe from the internet and try it. You look at it and see if it looks like "good glass" (unless it's a matte glaze by design, then you don't really know if it's melted or not!) and if it doesn't you guess at what to add and keep repeating the cycle until it looks like you want. The problem with that (besides time) is that it gives you no reason to believe that it is a stable glaze. Are we really OK with putting out glazes that are leaching copper into people's tea/coffee/food?<br />2. Take a recipe and use software to look at unity. Is the silica high enough? Does it have enough alumina? If it doesn't you can either adjust it or rule it out from the start. If it isn't melting enough does it have enough boron (or other flux)? If I need more boron and add a frit what does that do to silica and alumina? I don't mean to imply that silica and alumina are all there is to look at, but you can pretty much know that if they are not in a reasonable range the glaze will not be stable.<br /><br />You can take quite a few cone 6 glazes that people use and ruin them by simply leaving a lemon slice on them overnight (or a couple hours). Of course if it's a clear glaze or has only a tiny bit of iron in it, there is really nothing to leach out (though the glaze may fail or dull). But if it has cobalt or copper, you don't want your customers eating/drinking that. Obviously if you create indoor sculpture this problem isn't a concern.<br /><br />It really doesn't take much time to learn a few parameters to judge whether a glaze should be stable or not. Ultimately, unity numbers aren't the whole story and you need to test also. But it is a huge shortcut if the goal is to provide long-lasting, non-poisonous glazes to our customers.<br /><br />All of the above refers to cone 6. It is significantly easier to make a stable cone 10 glaze.<br /><br />Linda,<br />my word was suato. Not nearly as cool!<br /><br />-MikeAnonymoushttps://www.blogger.com/profile/03543517431054091680noreply@blogger.comtag:blogger.com,1999:blog-6574046592294768817.post-69179749618041121202009-09-09T10:22:02.672-04:002009-09-09T10:22:02.672-04:00Boy what a lot of work researching glazes, but hop...Boy what a lot of work researching glazes, but hopefully in the end you'll get just the perfect one you can use for years. Hey my word verification is oldcar, hehe.Linda Starrhttps://www.blogger.com/profile/04364078667554676592noreply@blogger.comtag:blogger.com,1999:blog-6574046592294768817.post-56590370613166121372009-09-09T09:55:59.404-04:002009-09-09T09:55:59.404-04:00But, but, but, it all requires so much patience (w...But, but, but, it all requires so much patience (whine, whine) and all that sciencey stuff and words like percentages, calculations and formulas.Patricia Griffin Ceramicshttps://www.blogger.com/profile/11205981725964222971noreply@blogger.comtag:blogger.com,1999:blog-6574046592294768817.post-55586655169941787342009-09-09T09:08:41.114-04:002009-09-09T09:08:41.114-04:00I don't know if you already do this, but using...I don't know if you already do this, but using glaze calculation software can be a HUGE help. When you look at the unity formula for a glaze you can really see what it's made of. So, for example if you want more melt while keeping your alumina and silica within an acceptable range you can determine what type of boron frit to add. Stuff like that. Once you have a couple parameters for what makes a stable glaze it really isn't hard to get the hang of. Many cone 6 recipies floating around are not very stable and will leach out any oxides added to them.<br />A year or so ago I wrote a free website to allow people to store recipies and calculate the unity formula for your glazes. The site is http://www.glazecalculator.com/.<br />Also, you can post your recipes. Here is the info on the glaze you posted as an example:<br />http://www.glazecalculator.com/glazecalc/recipes/11705/view.aspx<br /><br />-MikeAnonymoushttps://www.blogger.com/profile/03543517431054091680noreply@blogger.com