Dishwasher Safe Testing Insight

[Min]

On 9/30/2019 at 7:48 PM, DBPottery said:

I tested some recipes they provided in their book and did a whole lot of work with glaze calculation software to get the percent makeup of materials as close to their Unity formula and they said they considered these glazes durable.

@DBPottery, I plunked your recipes into Insight along with the original ones, good job on using your ingredients to sub for some of theirs. Your chemistry looks good but it could be tweaked slightly to get the original amounts of silica and alumina into the glazes. One of the cornerstones of having a durable glaze is to have enough of both of those in the glaze. Might not make a difference between your amounts and the original but thought I'ld pass it along. Your recipe on the left, original in the middle and my version (using your materials) on the right.

 

 

[DBPottery]

22 hours ago, Bill Kielb said:

Gloss meter and persistence is definitely doable. Lab tests get expensive and you likely have to order something other than cadmium and lead which you pretty much know is not in your glazes already. Durability and RO is about the best I see at this point. Leaching from oxides becomes a permissible level thing and whether one can actually consume enough to reach the limits.

The Katz spreadsheet is pretty rough in its basic form, I added some simple VBA code and some colorant research and a chem research tab. we have his permission to redistribute with the changes. I made it a five tab and just do a single glaze at a time with four trials. Also allows copying one glaze forward to the next trial so helps with the typing a bit. I use it for quick simple analysis. The chem research tab allows you to quickly filter and sort. It’s fairly useful and as we improve the worksheet I send out the updates to about 20 folks who have opted in.

Message me if you are interested and we will figure a way to get it to you.

I will message you. I'd love to get a copy. Yes, lab testing will get expensive. You are right that I pretty much know lead and cadmium are not in the glazes; however, I found from the materials analysis I managed to obtain, most of the colorants (cobalt, iron, copper, etc.) contain various impurities in very small amounts. 

A few examples:

Red Iron Oxide has lead at 30ppm and arsenic at 20 ppm. 

Cobalt carbonate has lead at 0.0002%

Copper carbonate has lead at 50-100ppm.

Most people I've talked to so far say in a durable glazes these levels probably won't be detectable in a leach test. I asked the authors of Master Cone 6 Glazes and they think when they wrote the book the technology wasn't there to detect impurities at that level. My raw materials supplier said what they sell is what is used by glaze manufactures. 

[DBPottery]

54 minutes ago, Min said:

@DBPottery, I plunked your recipes into Insight along with the original ones, good job on using your ingredients to sub for some of theirs. Your chemistry looks good but it could be tweaked slightly to get the original amounts of silica and alumina into the glazes. One of the cornerstones of having a durable glaze is to have enough of both of those in the glaze. Might not make a difference between your amounts and the original but thought I'ld pass it along. Your recipe on the left, original in the middle and my version (using your materials) on the right.

 

 

Thanks for doing this and thanks for the compliment. I spent a bunch of time to get it to work. This is when I first realized making your own glazes won't be easy, especially when materials may no longer be available or you can't find them. 

[Bill Kielb]

2 hours ago, DBPottery said:

I will message you. I'd love to get a copy. Yes, lab testing will get expensive. You are right that I pretty much know lead and cadmium are not in the glazes; however, I found from the materials analysis I managed to obtain, most of the colorants (cobalt, iron, copper, etc.) contain various impurities in very small amounts. 

A few examples:

Red Iron Oxide has lead at 30ppm and arsenic at 20 ppm. 

Cobalt carbonate has lead at 0.0002%

Copper carbonate has lead at 50-100ppm.

Most people I've talked to so far say in a durable glazes these levels probably won't be detectable in a leach test. I asked the authors of Master Cone 6 Glazes and they think when they wrote the book the technology wasn't there to detect impurities at that level. My raw materials supplier said what they sell is what is used by glaze manufactures. 

Good catch, good info! 

Thanks, my colorant lists do not reflect that in their composition analysis.

Spreadsheet in your email with some bonus stuff.

enjoy!